Pathways of lymph flow through intestinal lymph nodes in the horse

In the horse, several thousand lymph nodes receive lymph from the intestine, part of which is very large and contains microorganisms that enable the animal to utilize refractory dietary constituents such as cellulose. The aim of this study was to describe the pathways by which lymph is delivered into, traverses, and is drained from these lymph nodes. These pathways were studied with either Microfil or methacrylate casting materials and with light and electron microscopy. The afferent lymphatic vessel delivering lymph into one of the nodes divides over the capsular surface and within trabeculae into terminal branches, and these are continuous with the subcapsular and trabecular sinuses through rounded holes up to 30 μm across. Lymph is conveyed from the subcapsular and trabecular sinuses through the cortex by four types of sinuses: trabecular sinuses, cortical tubular sinuses, tubulelike sinuses with a network of stellate cell processes, and sinuses between cortical cords. It is conveyed through the medulla by sinuses both within and between medullary cords. Lymph is drained from these sinuses by initial efferent lymphatics of three types: those between medullary cords, those within the subcapsular sinus overlying medullary or cortical cords, and those within trabeculae. All three types are continuous with surrounding sinuses through holes 5–30 μm across. These three alternative routes for lymph drainage may ensure adequate lymph flow during different intranodal conditions that may exist when the node is responding to microcrganisms or other foreign materials.     

Myocardial dysfunction in ankylosing spondylitis.

Echocardiographic evidence has suggested abnormalities of the myocardial function in patients with ankylosing spondylitis. In this work the cardiac function in patients with ankylosing spondylitis and in normal volunteers was evaluated. Twenty four normal volunteers and 21 patients with ankylosing spondylitis aged 18-45 were studied. None had overt cardiac disease. Cardiac function was assessed at rest with echocardiography, at rest and during supine bicycle exercise using radionuclide angiography in the left anterior oblique position following equilibration with 740 MBq of technetium-99. The subjects undertook supine bicycle exercise with 30 W increments every three minutes to the point of fatigue. Comparison of data from normal volunteers and patients with ankylosing spondylitis were made using Student's t test for independent samples or the Mann-Whitney non-parametric technique, as appropriate. Subjects were matched for age, sex, height, and weight. There were no echocardiographic differences; however, global nuclide left ventricular function showed several differences between normal volunteers and patients with ankylosing spondylitis. The peak filling rate during exercise was significantly lower in patients with ankylosing spondylitis: normal volunteers 6.5 (SD 1.2); patients with ankylosing spondylitis 5.7 (1.2). The time to reach peak filling during exercise was significantly lower in patients with ankylosing spondylitis: normal volunteers 102 (22); patients with ankylosing spondylitis 120 (23). Regional analysis also showed differences between patients with ankylosing spondylitis and normal volunteers both at rest and during exercise. In the anteroseptal region the filling fraction and peak filling rate were significantly lower in patients with ankylosing spondylitis. Most of the differences (although not all) were in the variables of diastolic function. This study shows that there are subtle abnormalities in cardiac function in patients with ankylosing spondylitis. The major abnormalities are in the diastolic function, suggesting a decrease in left ventricular compliance.     

The solid variant of adenoid cystic carcinoma of the cervix.

We studied seven examples of the solid variant of adenoid cystic carcinoma of the uterine cervix in postmenopausal women who presented with vaginal bleeding and a large ulcerated or polypoid cervical mass. The tumors lacked the characteristic cribriform pattern of conventional adenoid cystic carcinoma. The neoplastic cells were small, undifferentiated, or basaloid and grew in cords, nests, trabeculae, and nodules. Foci of squamous cell carcinoma were seen in three tumors and areas of necrosis in four. A characteristic feature was the production of abundant periodic acid-Schiff's procedure (PAS)-positive basement membrane material that was immunoreactive for collagen IV and that in some areas compressed tumor cells. Electron microscopy on three cases showed globules and cylinders of redundant basal lamina. The tumor cells were joined by desmosomes and contained bundles of tonofilaments. Material similar to basement membrane material appeared to be intracytoplasmic in two tumors. No neurosecretory granules or myoepithelial cells were found. Four deaths were tumor related. Two patients are currently alive, but with local recurrence or metastases; another is alive and well 19 months after surgery. We believe that the solid variant of adenoid cystic carcinoma of the cervix is a distinctive neoplasm that should be separated from small cell carcinomas with or without endocrine features, adenoid basal cell carcinoma, and squamous cell carcinoma.     

Oxyphil and squamous variants of medullary thyroid carcinoma

Two unusual morphologic variants of medullary thyroid carcinoma not previously described are reported. The first tumor was composed predominantly of large eosinophilic cells indistinguishable at the light microscopic level from Hürthle cells. Focal areas of conventional medullary carcinoma were also present. Electron microscopic study showed mitochondrion-rich cells containing round neurosecretory granules. Immunoreactive calcitonin and carcinoembryonic antigen (CEA) were demonstrated within most tumor cells. The second tumor had areas of typical medullary carcinoma but exhibited extensive squamous differentiation. The tumor was positive for CEA, neuron-specific enolase, and chromogranin but negative for calcitonin. Oxyphil and squamous cells must be added to the long list of cell types that have been described in medullary thyroid carcinoma.     

Risk factors for acquisition of multiply drug-resistant gram-negative bacteria

Some bacteria are naturally resistant to many antibiotics and most can become multiply resistant. Multiply resistant gram-negative bacteria have proved a particular problem over the last 30 years, but the development of new agents has lessened their significance for most clinicians. Now, however, clinical practice is threatened by the lack of new classes of antibiotics, the widespread emergence of resistance and the advent of plasmid-mediated cephalosporinases by which the spread of resistance is likely to be rapid. Increased use of prophylaxis in immunosuppressed and intensive care patients is likely to aggravate the problem, as is the use of new broad-spectrum agents in the community. More directed and restricted antibiotic use and better education of patients and prescriber are necessary to contain the problem of antibiotic resistance. Improved surveillance of sensitivity trends is essential. Many outbreaks also are associated with poor infection control techniques. The cost of outbreaks due to multiply resistant organisms and lack of compliance with infection control procedures needs to be properly studied. While many predisposing factors for the acquisition of these organisms and the development of infection are understood, the multifactorial nature of illness in many patients complicates the issue, necessitating further study of risk factors and preventative and therapeutic measures.     

Comparison of ultrasonic cleaning schemes: a pilot study.

OBJECTIVE: Ultrasonic cleaning is an effective method for cleaning dental instruments prior to sterilisation. However, there are few studies that directly compare precleaning and ultrasonic cleaning solutions. This study evaluated the efficacy of different ultrasonic cleaning schemes. METHOD AND MATERIALS: Twenty representative dental instruments, five of which were soiled with a mixture of blood and hydroxyapatite, were used in a series of cleaning runs. Cleaning employed a presoaking agent, ultrasonic cleaning, or a combination of both. Two presoaking agents (Non-ionic Ultrasonic Cleaning Solution and ProEZ Foaming Enzymatic Spray) plus five ultrasonic cleaners (UltraDose, General Purpose Cleaner, Co-enzyme Concentrate, Enzol Enzymatic Detergent, and Non-ionic Ultrasonic Cleaning Solution) were compared, with tap water serving as a control. There were two cleaning times: seven and 15 minutes. After rinsing, the working ends of the instruments underwent scrubbing for 20 seconds using a dental polishing brush held in a haemostat. After scrubbing, the brush and instrument were placed in a tube containing sterile saline. Vortexing of the tube lasted 30 seconds. Testing for the post-cleaning presence of blood involved Hemastix dipsticks. These sticks measure minute amounts of blood in urine and can detect as few as 35 red blood cells per ml. Comparisons of colour change were made to a standard scale followed by assignment of numeric values. RESULTS: Tap water was the poorest cleaning solution, while UltraDose was the most effective. Blood removal improved when cleaning time was increased from seven to 15 minutes. The combined effect of a presoak immersion followed by ultrasonic cleaning was the most effective cleaning scheme overall. Cleaning by either ultrasound or presoaking only was less effective. Some instruments were more difficult to clean than others. CONCLUSION: Within the constraints of the small number of test runs performed, it was concluded that application of a presoak agent before ultrasonic cleaning produced the most effective instrument-cleaning regimen.     

Tumor targeting by an aptamer.

Aptamers are small oligonucleotides that are selected to bind tightly and specifically to a target molecule. We sought to determine whether aptamers have potential for in vivo delivery of radioisotopes or cytotoxic agents. METHODS: TTA1, an aptamer to the extracellular matrix protein tenascin-C, was prepared in fluorescent and radiolabeled forms. After in vivo administration, uptake and tumor distribution of Rhodamine Red-X-labeled aptamer was studied by fluorescence microscopy. In glioblastoma (U251) and breast cancer (MDA-MB-435) tumor xenografts, biodistribution and imaging studies were performed using TTA1 radiolabeled with (99m)Tc. Tenascin-C levels and tumor uptake were studied in a variety of additional human tumor xenografts. To assess the effect of radiometal chelate on biodistribution, mercapto-acetyl diglycine (MAG(2)) was compared with diethylenetriaminepentaacetic acid and with MAG(2)-3,400-molecular-weight PEG (PEG(3,400)). RESULTS: Intravenous injection of fluorescent aptamer TTA1 produced bright perivascular fluorescence in a xenografted human tumor within 10 min. In the ensuing 3 h, fluorescence diffused throughout the tumor. Labeled with (99m)Tc, TTA1 displayed rapid blood clearance, a half-life of less than 2 min, and rapid tumor penetration: 6% injected dose (%ID)/g at 10 min. Tumor retention was durable, with 2.7 %ID/g at 60 min and a long-lived phase that stabilized at 1 %ID/g. Rapid tumor uptake and blood clearance yielded a tumor-to-blood ratio of 50 within 3 h. Both renal and hepatic clearance pathways were observed. Using the (99m)Tc-labeled aptamer, images of glioblastoma and breast tumors were obtained by planar scintigraphy. Aptamer uptake, seen in several different human tumors, required the presence of the target protein, human tenascin-C. Modification of the MAG(2) radiometal chelator dramatically altered the uptake and clearance patterns. CONCLUSION: TTA1 is taken up by a variety of solid tumors including breast, glioblastoma, lung, and colon. Rapid uptake by tumors and rapid clearance from the blood and other nontarget tissues enables clear tumor imaging. As synthetic molecules, aptamers are readily modified in a site-specific manner. A variety of aptamer conjugates accumulate in tumors, suggesting imaging and potentially therapeutic applications.     

Pericapillary fibrin cuffs in venous ulceration. Persistence with treatment and during ulcer healing.

A recent hypothesis suggests that venous hypertension leads to ulceration through the formation of pericapillary fibrin cuffs, which are presumed to impede the exchange of oxygen and other nutrients. In this report, we evaluated by direct immunofluorescence the presence of pericapillary fibrin at the edge of venous ulcers during the course of treatment with elastic compression. In an initial group of 23 patients studied at baseline, pericapillary fibrin cuffs were detected in 20 (91%) of 22 patients. The intensity of fibrin staining, rated blindly on a scale of 0 to 3, could not be correlated with several baseline parameters, including the clinical presence and extent of lipodermatosclerosis, ulcer size, venous recovery time, and transcutaneous oxygen measurements (TcPO2) taken next to the ulcer. Eleven of this initial group of 23 patients were randomly selected to receive elastic compression treatment, and were evaluated for the persistence of pericapillary fibrin at 60 and 120 days. Although a reduction (mean +/- SD = 50.2% +/- 25.7) in ulcer size occurred in 10 of the 11 patients, pericapillary fibrin was still present at the ulcer edge and with undiminished intensity. We conclude that pericapillary fibrin cuffs in venous ulcers persist with compression treatment and in spite of healing, and are unlikely to be directly related to the development of ulceration.