Bench test assessment of the new Raumedic Neurovent-P ICP sensor: a technical report by the BrainIT group

Summary. Background. In clinical practice, fiberberoptic and piezo-electric ICP probes are often used for measuring intracranial pressure (ICP). A number of similar technologies, although performing well in bench test studies, have been shown to exhibit unacceptable zero drift, fragility or both during trials conducted under clinical conditions. Recently, a new technology has become available, the Neurovent-P (Raumedic AG+CO, Raumedic, Germany). As a pre-requisite for a clinical trial, we have conducted and report on bench test studies to confirm the manufacturers long term zero-drift performance for this technology.Method. In a test rig static tests (recording of 20mmHg pressure) and dynamic tests, ranging from 5 to 50mmHg have been performed.Findings. 10 ICP probes have been tested for a total of 60 days. All the catheters, after the connection with the ICU monitor displayed a static pressure of 0±1mmHg and did not required pre-insertion alteration. At five days, mean zero drift was 0.6±0.9mmHg. Overall, zero drift ranged from 0 to 2mmHg. At a fixed static pressure of 20mmHg, the mean recorded value was 20.6±0.8mmHg, ranging from 19 to 23mmHg. A regression analysis of the relationship between the applied pressure and the recorded pressure during the dynamic tests of the 10 catheters yielded a correlation coefficient R² of 0.997. Applying the Altman and Bland method to assess the bias and confidence limits for the Raumedic catheter responses during the dynamic tests against the applied gold-standard hydrostatic column pressures, the average bias of –0.66±0.85mmHg, with 95% CLs of –2mmHg and 1mmHg.Conclusions. Mean zero drift, after five days, was very small and long-term continuous recording of a stable pressure was very precise. The response at dynamic tests, i.e. the changes of pressure in a wide range, was excellent. The average bias of the Raumedic catheter compared with the hydrostatic column is very small. After this bench test, the next and most critical step will be to conduct a trial of this promising technology under more demanding clinical environment.     

The distribution of extracellular matrix vesicles in healing of rat tibial bone three days after intramedullary injury

Summary The distribution of extracellular matrix vesicles on the third day of bone healing was studied by morphometric analysis of transmission electron micrographs. Detection and grouping of the vesicles was performed according to type, diameter, and distance from the calcified front. The different types were selected as follows: vesicles with electron-lucent contents (empty), vesicles with amorphous electron-opaque contents (amorphic), vesicles containing crystalline depositions (crystal), and vesicles containing crystalline structures with ruptured membranes (rupture). The majority of vesicles were between 0.07 µm and 0.12 m in diameter and were located at less than 3 m from the calcified front. The distribution of the empty, amorphic, crystal, and rupture vesicles was 23.2%, 74%, 2.5%, and 0.3% respectively. Their sequence of arrangement according to diameter was as follows: empty, amorphic, crystal, and rupture, the empty vesicles constituting the smallest and the rupture the largest type. Distances from the calcified front were similar for the empty, amorphic, and crystal vesicles, while the rupture type was located nearest to the front. The present observations support the widely acknowledged hypothesis on the role of extracellular matrix vesicles in mineralization. It is thought that the secretion of empty vesicles from the cell is followed by intravscular accumulation of amorphous Ca and Pi to form a hydroxyapatite crystal that, in turn, ruptures the vesicle's membrane. The maturation process is accompanied by an increase of the vesicular diameter and its approximation to the calcifying front.     

Anterior lumbar interbody fusion with carbon fiber cage loaded with bioceramics and platelet-rich plasma. An experimental study on pigs

Platelet-rich plasma (PRP) is an autogenous source of growth factor and has been shown to enhance bone healing both in clinical and experimental studies. PRP in combination with porous hydroxyapatite has been shown to increase the bone ingrowth in a bone chamber rat model. The present study investigated whether the combination of beta tricalcium phosphate (-TCP) and PRP may enhance spinal fusion in a controlled animal study. Ten Danish Landrace pigs were used as a spinal fusion model. Immediately prior to the surgery, 55 ml blood was collected from each pig for processing PRP. Three-level anterior lumbar interbody fusion was performed with carbon fiber cages and staples on each pig. Autogenous bone graft, -TCP, and -TCP loaded with PRP were randomly assigned to each level. Pigs were killed at the end of the third month. Fusion was evaluated by radiographs, CT scanning, and histomorphometric analysis. All ten pigs survived the surgery. Platelet concentration increased 4.4-fold after processing. Radiograph examination showed 70% (7/10) fusion rate in the autograft level. All the levels with -TCP+PRP showed partial fusion, while -TCP alone levels had six partial fusions and four non-fusions (P=0.08). CT evaluation of fusion rate demonstrated fusion in 50% (5/10) of the autograft levels. Only partial fusion was seen at -TCP levels and -TCP+PRP levels. Histomorphometric evaluation found no difference between -TCP and -TCP+PRP levels on new bone volume, remaining -TCP particles, and bone marrow and fibrous tissue volume, while the same parameters differ significantly when compared with autogenous bone graft levels. We concluded from our results in pigs that the PRP of the concentration we used did not improve the bone-forming capacity of -TCP biomaterial in anterior spine fusion. Both -TCP and -TCP+PRP had poorer radiological and histological outcomes than that of autograft after 3 months.     

Scanning electron microscopy-electron probe microanalysis study of the interface between apatite and wollastonite-containing glass-ceramic and rabbit tibia under load-bearing conditions after long-term implantation

Glass-ceramic implants containing oxy- and fluoroapatite [Ca₁₀(PO₄)₆(O, F₂)] and -wollastonite (CaSiO₃) were studied under load-bearing conditions in a segmental replacement model in the tibia of the rabbit. A 16-mm segment of the middle of the tibial shaft was resected at a point distal to the junction of the tibia and the fibula. The defect was replaced by a 15 mm-long hollow, cylindrical implant that was fixed by intramedullary nailing using Kirschner wire. The implants were 9 mm in diameter and 15 mm long bearing a central hole 3.05 mm in diameter. The rabbits used were killed 6 months, 1 year, 18 months, and 2 years after implantation. The interface between the bone and the glass-ceramic was investigated by scanning electron microscopy-electron-probe microanalysis (SEM-EPMA).None of the glass-ceramic implants broke, and the glass-ceramic had bonded directly to the bone tissue without any intervening soft tissue. A calcium-phosphorus layer (Ca-P layer) was observed at the glass-ceramic/bone interface. This layer was 30–100 m thick at 6 months after implantation, 60–110 m thick at 1 year after implantation, 80–200 m thick at 18 months, and 120–350 m thick at 2 years. At the lateral surface of the glass-ceramic uncovered by the bone, the calcium-phosphorus layer was 50–80 m thick at 6 months after implantation, 250–450 m thick at 1 year, 300 400 m thick at 18 months, and 300 m thick at 2 years. The thickness of the calcium-phosphorus layer increased moderately after long-term implantation. However, it was difficult to estimate the rate of increase in the thickness of calciumphosphorus layer.     

Large fibres in urinary calculi — Promoters of stone formation

Summary Large fibres (ø 10–20 m, length up to 5,000 m) are sometimes imbedded in urinary calculi. It may be that these fibres can catch sediment particles and promote stone growth. By scanning electron microscopy the morphology of the fibres was studied as well as the relationship of the fibres with crystalline stone components. The reported findings suggest that the fibres are possibly formed in the tubuli as the result of an hitherto unknown defect.     

Extravascular application of an intravascular ultrasound (IVUS) catheter during carotid endarterectomy to verify distal ends of stenotic lesions

Summary. Background. Intravascular ultrasound (IVUS) has been developed initially for intravascular imaging of coronary arteries to investigate vascular structures. We applied the IVUS catheter extravascularly to the cervical carotid arteries to obtain intra-operative ultrasound images during carotid endarterectomy (CEA). Intra-operative assessments of the distal ends of the stenotic lesions as well as pathological vascular structures are important, not only for exposing the lesions sufficiently but also for placing the shunt system safely.Method. An IVUS catheter (3.2 French/30MHz) was intra-operatively applied close to the outer surface of the cervical carotid arteries during CEA. Ultrasound transection vascular images were obtained in 33 consecutive patients (30 males and 3 females) with a mean age of 66.5 years.Findings. In 32 of 33 cases, extravascular application of IVUS catheter before making arteriotomies correctly depicted the distal ends of the internal carotid artery (ICA) stenotic lesions as a thin layer of vascular wall [0.64±0.16mm (mean±SD) compared with 1.66±0.42mm for carotid plaque] with intravascular blood flow. Based on the IVUS findings, we were able to adequately expose the normal ICA portion distal to the stenotic lesion before making the arteriotomy even in cases with stenotic lesions at very high positions, and to insert shunts safely. Furthermore, the properties of lesions and blood flow were also verified. However, it was difficult to examine the far vascular wall.Conclusions. Extravascular application of IVUS catheter is efficient for intra-operative evaluation of the distal end of the stenotic lesion especially in cases with stenotic lesions at very high positions and cases in whom pre-operative angiograms did not clearly demonstrate the distal end. The findings also demonstrate the properties of lesions and completeness of CEA.     

Absorptiometry and “osteoporosis”: problems

connecting the dots between diverse clinical and other matters and an updated bone physiology reveals relationships that could modify some ideas about the roles and uses of absorptiometry in osteoporosis work. Herein, absorptiometry means that part of clinical densitometry that depends on X-ray absorption by bone and other tissues, thus excluding ultrasound methods and magnetic resonance imaging. The modifications concern, in part, some limitations of bone mineral density data, the kinds of physiological information that absorptiometry can and cannot provide, the relative importance of bone mass and whole-bone strength, how to define and study bone health and osteoporosis, and two kinds of osteoporotic fractures. As those modifications concern important national health care issues, they deserve answers based on hard evidence. Identifying those modifications might help others to evaluate them.     

FT-IR microscopic mappings of early mineralization in chick limb bud mesenchymal cell cultures

Summary Chick limb bud mesenchymal cells differentiate into chondrocytes and form a cartilaginous matrix in culture. In this study, the mineral formed in different areas within cultures supplemented with 4 mM inorganic phosphate, or 2.5, 5.0, and 10 mM -glycerophosphate (GP), was characterized by Fourier-transform infrared (FT-IR) microscopy. The relative mineral-to-matrix ratios, and distribution of crystal sizes at specific locations throughout the matrix were measured from day 14 to day 30. The only mineral phase detected was a poorly crystalline apatite. Cultures receiving 4 mM inorganic phosphate had smaller crystals which were less randomly distributed around the cartilage nodules than those in the GP-treated cultures. GP-induced mineral consisted of larger, more perfect apatite crystals. In cultures receiving 5 or 10 mM GP, the relative mineral-to-matrix ratios (calculated from the integrated intensities of the phosphate and amide I bands, respectively) were higher than in the cultures with 4mM inorganic phosphate or in the in vivo calcified chick cartilage.     

Experimental study of drainage and granulation in response to the intra-articular injection of particles in rat knee joints

Reactive granulation and drainage of intraarticularly injected plastic particles in rat knee joints was examined by light and electron microscopy. The knee joints and associated iliac lymph nodes were excised at various intervals after the injection of latex beads (1 m) or fluoresbrite particles (0.2 m or 10 m) from 5 min until 3 months after the injection. Particles in the lymphatic or blood vessels were successfully demonstrated by an enzyme-histochemical method (5-nucleotidase staining). Five min after the injection, most of the particles were scattered on the surface of the synovial membrane, and some particles were phagocytosed by synovial lining cells. After 5 h, neutrophils had phagocytosed particles which adhered to fibrin in the joint cavity. Twelve h after the injection, after the neutrophils had died, those same particles were phagocytosed by macrophages in the joint cavity. One day after the injection, Fluoresbrite particles (0.2 m) phagocytosed by macrophages were found in the iliac lymph nodes, while latex particles (1 m) were detected in the iliac lymph nodes 3 days after the injection. Some Fluoresbrite particles (10 m) were seen in the 5-nucleotidase-positive lymphatic vessels in the synovial membrane. Three months after the injection, many macrophages filled with particles had formed granulation tissue in the synovial membrane, and macrophages containing phagocytosed particles were also seen increasingly in the iliac lymph nodes. Our findings suggested that neutrophils and macrophages phagocytosed injected particles in the joint cavity, and that the macrophages brought the particles into the deep layer of the synovial membrane. Phagocytic macrophages also carried the particles to the iliac lymph nodes through lymphatic vessels in the synovial membrane. There were no morphological differences in the processes of granulation and drainage between the two different sized plastic particles (1 m and 0.2 m), except for the behavior of the macrophages phagocytosing the particles.     

Comparison of anesthetic effects of epidural and intravenous administration of buprenorphine during operation

Thirty six patients were received epidural anesthesia with or without buprenorphine (BPN) during upper abdominal surgery. They were divided into three groups of 12 patients as follows; G-I received 20ml of 1% lidocaine epidurally, G-II received 20ml of 1% lidocaine epidurally and 0.6mg BPN intravenously, G-III received 20ml of 1% lidocaine with 0.6mg BPN epidurally. Additional 5ml of 1% lidocaine was given to any patient if systolic blood pressure or heart rate increased 10% compared to control value. Trachea was intubated following anesthetic induction with thiopental. The lungs were ventilated with a mixture of N₂O/O₂ (33%) and pancuronium was used for muscle relaxation. The total required doses of lidocaine in G-II and G-III were decreased 60% compared to control group (G-I) (P 0.05). The mean period of time until the first administration of pentazocine for postoperative pain was 13 ± 10hr (mean ± SD) in G-II and 19 ± 24hr in G-III compared to 5 ± 4hr in G-I (P 0.001). The dose of the administration of pentazocine that was required for pain relief during the first 48 postoperative hr in G-III was 54 ± 10mg (mean ± SD) compared to 150 ± 21mg in G-I (P 0.02) and 106 ± 28mg in G-II (P 0.05). Recovery from anesthesia in G-III was more rapid than that in G-I (P 0.05). The Pa_{CO 2} values in G-II and G-III increased 15% compared to control group at about 4hr and 8hr after administration of BPN, but any clinical treatment was not needed for them. Nonrespiratory side effects, e.g., nausea, vomiting, fatigue and headache, were comparably common in all groups. Mild hematuria associated with acute hypotension occurred in two patients in G-II (17%) immediately after the intravenous injection of 0.6mg of BPN. The results showed that 0.6mg of BPN given epidurally demonstrated better anesthetic and more potent postoperative analgesic effects and lesser side effects than 0.6mg of BPN given intravenously in patients undergoing upper abdominal surgery.(Yonemura E, Fukushima K.: Comparison of anesthetic effects of epidural and intravenous administration of buprenorphine during operation. J Anesth 4: 242–248, 1990)     

An immunohistochemical study of glucagonoma conducted on the metastatic lymph nodes from a patient with recurrent metastatic glucagonoma: Report of a case

In this report, we briefly present the case of a 67-year-old woman who developed recurrent glucagonoma with lymph node metastasis. An immunohistochemical study of the metastatic tumor revealed immunoreactivity of glucagon and protein kinase C (PKC)-, -, and - in the tumor cells, two types of which were seen by electron microscopy. One type had abundant secretory granules and mitochondria, while the other had few granules and mitochondria. Some granules were similar to typical A cell granules and others were atypical. An immunoelectron microscopic demonstration revealed PKC-, -, and - immunostaining in the cytoplasm of all the tumor cells, while some secretory granules had PKC immunostaining, and others had no immunostaining. Thus, it appears that metastatic glucagonoma and its associated granules are composed of two types of mature and immature cells or granules. As immunoreactivity of PKC- and - was found in the tumor cells, but not in the normal A cells of the islets of Langerhans, the PKC subspecies and , which are not present in normal pancreatic A cells, may exist in human glucagonoma cells.     

Demonstration of the 5-flap technique

Summary Demonstration of the 5-flap technique which is double opposed Z-plasty and Y – V advancement is presented. A 4×4 gauze serves to demonstrate this technique.The authors dedicate this paper to the dear memory of their teacher, the late Prof. Zvi Neuman, who passed away untimely on March 22, 1977     

Preoperative control of a ruptured anastomotic femoral “pseudoaneurysm” by balloon catheter: A combined radiologic and surgical approach

Inflow control of a rapidly expanding or ruptured femoral anastomotic pseudoaneurysm can be fraught with hazard. Occlusion of an anastomotic femoral aneurysm with a balloon catheter offers the surgeon a simple method of gaining inflow control prior to surgery. After achieving inflow control with the balloon catheter, the surgeon can incise the anastomotic aneurysm without significant blood loss, control back bleeding with balloon occlusion catheters, and with relative ease and safety repair or replace the anastomotic aneurysm as indicated. An illustrative case is presented.     

Zur Entwicklung der Hüftluxationsbehandlung im Laufe der Medizingeschichte

Zusammenfassung Die historische Entwicklung der ärztlichen Heilmaßnahmen zur Hüftgelenksreposition bei der typischen angeborenen Verrenkung ist ein interessantes Spiegelbild der gesamten Medizingeschichte und der Orthopädie im besonderen. Schon Hippokrates hat auf Grund recht guter pathologisch-anatomischer Sachkenntnis in seinem bedeutenden Werk i — über die Einrichtung der Gelenke — ein ebenso einfaches wie zweckmäßiges Extensionsverfahren am luxierten Bein dargestellt. Nach einer auffallend langen Zeitspanne resignierter Beschränkung auf rein palliative Therapie folgte eine radikal-aktive Ära der operativ-chirurgischen Reposition der kongenitalen Hüftluxation — vor allem repräsentiert durch die blutige Einrenkungsmethode von Hoffa und Lorenz. Erst die klinischen Mißerfolge dieses heroischen Vorgehens mit seiner Möglichkeit eines genauen bioptischen Studiums der weichgewebigen und artikulären Skeletsituation schufen die Grundlage zur Entwicklung der klassischen unblutigen Repositionsmethode, um deren Primat zwischen dem Italiener Paci und Adolf Lorenz eine heftige Kontroverse entstand. Zur stabilen Retention der eingerenkten Luxationshüfte wurden in der Folgezeit sehr verschiedenartige Gipsfixationen und Spreizapparate empfohlen — am bekanntesten die Lorenzprimärstellung, die weniger forcierte Langeposition und das geniale Schedelaufrad. Die moderne Orthopädie hat für die operative Korrektur unblutig nicht zu reponierender Hüftluxationen, etwa beim Vorliegen eines weichgewebigen Interpositums, oder bei unbefriedigendem Behandlungsergebnis eine ganze Reihe chirurgischer Hilfsoperationen — jeweils mit ganz spezieller Indikation — zur Verfügung: Die blutige Einrenkung, die Pfannendachplastik bei mangelhafter knöcherner Formsicherung des Acetabulums, die Femurosteotomie bei bestehender Oberschenkeldeformität im Sinne einer Coxa valga oder pathologischer Antetorsion des proximalen Femurendes — schließlich die Arthroplastik mit oder ohne Endoprothese bei schmerzhaft-kontrakten Spätzuständen. Als ultima ratio kann in besonders schweren Fällen ein stabiles beschwerdefreies Standbein durch Arthrodese geschaffen werden. Selbstverständlich werden heute auch sämtliche bewährten sonstigen physikalischen Hilfsmittel und Heilverfahren — aktive und passive Gymnastik, temporäre Gamaschenextension und Apparatentlastung, Massage und Bäderbehandlung — zur Verbesserung von Form und Funktion der Luxationshüften in den großen Kreis therapeutischer Möglichkeiten einbezogen.Die Arbeit wurde auf die Initiative und unter der Leitung von Herrn Prof. Dr. Rupprecht Bernbeck, München, verfaßt.     

Expression of estrogen receptor-α and -β in anterior vaginal walls of genuine stress incontinent women

Our objective was to study the expression of estrogen receptor (ER) isoforms, ER- and ER-, in the anterior vaginal wall of menopausal and fertile women with genuine stress incontinence (SI) by immunohistochemistry and Western blot analysis. Eighteen menopausal women with SI who either were or were not taking estrogen/progestin replacement therapy and 14 fertile women with SI who either were or were not taking contraceptives were enrolled in the study. Biopsies from the suburethral anterior vaginal wall were obtained at tension-free vaginal tape (TVT) operation. Monoclonal antibody to ER- and polyclonal antibody to ER- were used to stain frozen sections of vaginal tissue. The receptor expressions were scored based on percentage of positive cells. ER- was detected in vaginal epithelial, stromal and smooth muscle cells. In menopausal SI women ER- was detected significantly more frequently in the vaginal walls of estrogen/progestin-treated patients than in those who were untreated. Fertile SI women had significantly higher expression of ER- than menopausal SI women. ER- was not observed in vaginal blood vessels. ER- was detected in epithelial and vascular smooth muscle cells of the vagina. No significant difference in ER- expression was observed between different groups of patients. The expression of ER- was not correlated with that of ER-. Both ER- and - were detected, indicating a potential role for both types of estrogen receptor in the human vaginal wall. The expression of ER-, but not of ER-, in menopausal SI women was regulated by estrogen/progestin replacement therapy. The presence of ER- in vaginal vascular smooth muscle cells raises the possibility of vascular effects of estrogen on the human vaginal wall.Abbreviations ER Estrogen receptor - SI Stress incontinence - TVT Tension-free vaginal tape - HRT Hormone replacement therapy - ABC Avidin–biotin–peroxidase complex - PBS Phosphate buffered saline - DAB DiaminobenzidineEditorial Comment: This was an interesting study in that it addressed the expression of estrogen receptors in incontinent women. There is not a control group of incontinent women. Conclusions regarding mechanisms of action or treatment with estrogen for incontinence cannot be made on the basis of the results. At best this study proves there is expression of estrogen receptors in vaginal tissues, which has been done by prior investigators.     

Transforming growth factor-β and prostate cancer

Summary This review focuses on the possible role of transforming growth factor- isoforms 1–3 (TGF) in prostate cancer. TGF1 appears to inhibit the cellular proliferation of normal prostate cells. Surprisingly, TGF1 is overexpressed in prostate cancer. To help explain this apparent paradox, it has been revealed that with tumor progression, prostate cancer cells acquire reduced sensitivity to the growth-inhibitory effects of TGF1. Aberrations of the TGF1 signaling pathway at the prereceptor, receptor, or postreceptor level may lead to prostate cancer cell resistance to TGF1 growth inhibition. Indirectly, elevated levels of TGF1 may induce host effects that may be beneficial to prostate tumor growth by suppressing the immune system, promoting angiogenesis and extracellular matrix formation, and enhancing metastatic potential. Consequently, TGF1 appears to be important in prostate carcinogenesis and tumorigenicity. TGF2 and TGF3 are only briefly presented as very little is known about their role in prostate cancer.     

Premature craniosynostosis a retrospective analysis of a series of 52 cases

Summary A retrospective analysis of a consecutive series of 52 cases with premature craniosynostosis is presented.Excellent functional, cosmetic, and social results could be achieved by resection of prematurely fused sutures and the creation of artificial growth sutures. Pronounced skull deformities have been corrected using the basket handle, the visor plasty, and the T-bone techniques or a combination of several of these skull form correction techniques. The surgical correction of the skull base by the frontal advancement technique in combination with orbitotomy was only necessary in 2 of our cases and could have been considered in 2 additional cases viewed retrospectively.Our results support the hypothesis that the primary cause of skull deformity is the premature closure of vault sutures and not a primary deformity of the skull base.     

Microscopic estimation of bacteria and cells in urine I. Theoretical considerations

The present paper describes theoretical considerations how urine samples should be microscoped so that cells/particles per microscope field well correlate to cells/particles per cm³. With the method described here, significant bacteriuria should be easily found and contaminations (below 10⁴ bacteria per cm³) would not be visible. Theoretically the method is suitable for microscoping bacteria, white cells, erythrocytes, epithelial cells and cylinders. The calculations presented indicate the importance of quality control in microscoping urine samples, and can explain the differences between the results obtained in different laboratories.     

A multiple technique approach to the analysis of urinary calculi

Summary 10 urinary calculi have been qualitatively and quantitatively analysed using X-ray diffraction, infra-red, scanning electron microscopy, X-ray fluorescence, atomic absorption and density gradient procedures. Constituents and compositional features which often go undetected due to limitations in the particular analytical procedure being used, have been identified and a detailed picture of each stone's composition and structure has been obtained. In all cases at least two components were detected suggesting that the multiple technique approach might cast some doubt as to the existence of pure stones. Evidence for a continuous, non-sequential deposition mechanism has been detected. In addition, the usefulness of each technique in the analysis of urinary stones has been assessed and the multiple technique approach has been evaluated as a whole.     

Quantitative evaluation of the bacteriostatic efficacy of amniotic membrane applied as a biological dressing over large contaminated wounds encountered in clinical practice

Summary Control of wound infection constitutes the most important aspect of wound management. A successful wound closure either by delayed primary/secondary suturing or by skin grafting cannot be performed unless the bacterial count in the tissues is well below the critical number of 10⁵ organisms per gram of tissue. In this study, the efficacy of the amniotic membrane in reducing bacterial infection when applied as a biological dressing over granulating wounds was compared with that of standard saline dressings. Bacteriological monitoring of wound flora was achieved by a three dimensional biopsy from an active portion of the infected wound. Such biopsies were taken from both test and control areas before membrane application and 72 h after application. The results of this study demonstrate that amnion dressings have a definite and significant antibacterial effect as seen by the marked decrease in bacterial colony counts after the dressing is applied to contaminated wounds. This effect of the amnion can be attributed to the intimate biological closure due to its excellent adherence on to the wound bed, facilitation of phagocytosis of the micro-organisms in the underlying healthier granulations and to certain antibacterial substances elaborated by the living amniotic cells.Presented at the Peet Prize Scientific Session of the 24th National Conference of the Association of Plastic Surgeons of India at Baroda, September 2, 1989