Purification of alkaline phosphatase from extracellular vesicles of fracture callus cartilage

Summary Extracellular matrix vesicles from fracture callus cartilage were isolated by differential centrifugation and resolved by equilibrium centrifugation on a discontinuous sucrose gradient into two bands. The phosphohydrolytic activity towards p-nitrophenyl phosphate, tetrasodium pyrophosphate and adenosine triphosphate was distributed similarly after differential and equilibrium centrifugation suggesting the association of this activity with the matrix vesicles. The two bands isolated by equilibrium centrifugation of the partially purified vesicular preparation demonstrated high levels of alkaline phosphatase activity. Observed with an electron microscope, the 1.07–1.14 g/cm³ band from the gradient was enriched in electron luscent matrix vesicles while the 1.27 g/cm³ band contained electron dense matrix vesicles. Enzymatic analysis of the 1.27 g/cm³ band indicated a slight contamination due to the presence of mitochondria and lysosomes while the 1.07–1.14 g/cm³ band gave no enzymatic indication of subcellular contamination. A phosphohydrolytic enzyme active towards p-nitrophenyl phosphate, tetrasodium pyrophosphate and adenosine triphosphate was purified from the 1.07–1.14 g/cm³ fraction by DEAE-cellulose column chromatography. Electron micrographs of callus cartilage sections demonstrated densification of the plasma membrane and matrix vesicles following substrate incubation with-glycerophosphate or tetrasodium pyrophosphate. The histochemical and biochemical data indicate that a phosphatase, with multiple substrate specificity, is a component of fracture callus cartilage matrix vesicles.     

The role of pancreatic venous sampling in the localization of occult insulinomas

The palpation and enucleation of occult insulinomas (less than 15 mm) can be a difficult surgical problem even with good arteriographic localization. In the authors' limited experience, confirmation of arteriographic findings by pancreatic venous sampling provided little additional localizing information. However, if arteriography is negative or equivocal, venous sampling can indicate the segment of pancreas to be "blindly" resected if the adenoma is not palpable. Venous sampling may be misleading in polyendocrine syndromes because of the frequency of multiple adenomas and variable hormone production.     

Scintigraphic assessment of heterotopic cardiac transplants

Patients receiving heterotopic ("piggyback") cardiac transplants, when the patient's own and transplanted donor hearts are connected in parallel, present special problems in determining their relative contributions to total cardiac function. Three patients who had transplants because of intractable heart failure were studied using first pass and gated equilibrium technetium-99m-labeled blood pool scintigraphy. In one patient, thallium-201 myocardial perfusion scans were obtained. These nuclear cardiology techniques provided anatomic and functional information noninvasively that proved helpful in patient management.     

Chondrocyte-to-osteocyte transformation in grafts of perichondrium-free epiphyseal cartilage

When perichondrium-free pieces of embryonic quail epiphyseal cartilage are incubated on the chorioallantoic membranes of chick embryos, 2 developmental changes are observed. First, most grafts develop a periosteum in which the osteoblasts and osteocytes are of donor, i.e., chondrocytic origin. No such periosteum is observed around explants of demineralized, inductive bone matrix. Second, the matrix surrounding some chondrocytes within the original graft became more bone-like with respect to staining pattern, birefringence and collagen morphology. We conclude that, under some conditions, the avian chondrocyte may in situ or subsequent to release from the cartilage lacuna synthesize a bone-like matrix and, in this sense, be thought to have undergone a "transformation" into an osteocytic or osteoblastic type of cell.     

Directional transport and integration of donor DNA in Haemophilus influenzae transformation.

DNA transport and integration in Haemophilus influenzae transformation was studied with a plasmid clone of homologous DNA (pCML6). Our results indicate that: (i) donor DNA enters specialized membranous extensions on the cell surface, which we have termed "transformasomes"; (ii) linear DNA undergoes degradation upon exiting transformasomes; and (iii) DNA without a free end remains within transformasomes and is not degraded. By comparing the fate of label from uniformly labeled versus middle-labeled DNA, it appears that donor DNA undergoes degradation from an end prior to recombining with the chromosome. Using donor DNA with covalently closed termini (hairpin ends) prevents efficient exit from transformasomes. When one hairpin is removed, exit of donor DNA is shown to be directional from the free end, with preferential homologous integration of the 3' strand from that end.     

Australian Aborigines and alcohol: A review

Following a summary of the relevant historical and legislative background, this article reviews the literature on: (i) rates of alcohol usage and problem drinking in Aboriginal populations; (ii) adverse effects of drinking; (iii) suggested causes of problem drinking among Aborigines; and (iv) treatment and preventive initiatives. The need to examine Aboriginal alcohol use in the wider context of socio-economic deprivation and rapid social change is emphasized. Key issues warranting further research attention are identified and, while recognizing the difficulties inherent in doing so, suggestions are made as to how the quality of research in the area might be raised. It is concluded that, without long-term planning and commitment of the necessary resources by government, little progress will be made in reducing the problems associated with Aboriginal use of alcohol.     

Effects of body movement restraint on cardiac response to auditory stimulation in sleeping infants

When exposed to an unfamiliar and sudden noise, infant rodents may show an abrupt bradycardia, as part of a "fear-paralysis response". The response is enhanced by body movements restraint. To investigate if this reaction is seen in humans, 15 normal infants with a median age of 12 weeks were studied polygraphically. They were exposed to a 100-dB (A) white noise, while sleeping in REM sleep. Each infant was studied in both "unrestrained" and "restrained" conditions. Restraint of body movement was obtained by means of sand bags and tightly-binding bed sheets. During movement restraint, the infants had a significantly greater and earlier decrease in heart rate compared with during the unrestrained condition. No infant had a minimal heart rate less than 95 beats/min. The present observation raises questions about the possible unfavorable effects of tightly wrapped bed sheets around sleeping infants.     

Regional odontodysplasia. Case report with etiologic and treatment considerations.

Regional odontodysplasia, a relatively rare developmental abnormality of the dental hard tissues, most often unilaterally and segmentally involves the anterior maxillary teeth of young females. Patients often have pulpal pathosis, periodontal manifestations, and irregularities of the eruption sequence of the affected teeth. The resultant reduced density of the enamel and dentin imparts a radiographic appearance of "ghosting" with correspondingly enlarged pulp chambers and canals. Etiology is uncertain; numerous local and systemic factors have been proposed. Treatment may sometimes be controversial, and timing of extractions and restorative procedures is critical. This case report illustrates the signs and symptoms of regional odontodysplasia, to aid clinicians in early recognition of the condition, to provide further evidence that a local circulatory disorder might be involved in its pathogenesis, and to illustrate treatment options that consider the patient's development and welfare.     

Support services for family practice residents.

BACKGROUND. Internship and residency are stressful experiences for physicians in training. Residency programs vary in their provision of supportive services for residents. METHODS. A random sample of 50% of the nation's family practice residency programs was surveyed to determine the prevalence of 19 support services, 10 of which were assessed a decade previously. Programs were also asked about on-call frequency, vacation benefits, and program size. RESULTS. Approximately 91% of the programs responded. The surveys indicated that residents were on call an average of once every four nights, a 10% decrease from a decade ago. The prevalence of three support services had increased over the last decade: seminars and speakers on the stresses and conflicts of being a physician, support groups for residents, and child care services. "Night-float" rotations and part-time residencies are the least offered support services of those studied. CONCLUSIONS. Support for family practice residents is increasing, yet in many cases remains inadequate.     

Infrapopliteal prosthetic graft patency by use of the distal adjunctive arteriovenous fistula

From November 1979 through December 1989, 210 distal arteriovenous fistulas were constructed as adjuncts to tibial and peroneal vascular reconstructive procedures in 203 patients threatened with limb loss. Two-year cumulative patency rates were calculated by grouping patients on the basis of changing indications in sequential time periods: group 1 (n = 61): 1979 to 1983, 18%; group 2 (n = 80): 1983 to 1986, 33%; group 3 (n = 69): 1986 to 1989, 44%. Although the therapeutic results observed in these groups are not statistically comparable, they show a perceptible trend. Postoperative arteriography showed that flow is prograde in the distal vessels beyond the distal arteriovenous fistula. Graft surveillance by duplex ultrasonography also confirmed that flow in the distal arteries is prograde and that "steal" does not occur. Peak systolic velocity (174 +/- 38 cm/sec) and mean velocity (92 +/- 23) flow rates are increased in grafts with patent distal arteriovenous fistulas compared to those bypasses with closed distal arteriovenous fistulas (p less than 0.01). There were no differences in the flow measurements for the arteries beyond the distal anastomoses and distal arteriovenous fistulas, confirming the prograde nature of the distal flow. In 22 patients analysis of graft and fistula patency by duplex sonography showed that one fourth of all grafts were patent without fistulas at 1 and 2 years after operation. Alternatively, 68% of patent grafts at 1 year had patent fistulas and 58% had patent fistulas at 2 years. We conclude that the distal arteriovenous fistula will increase graft flow and simultaneously prevent distal arterial overload without causing "steal." This technique should be considered whenever a prosthetic graft is necessary for crural reconstruction and only in selected instances of revascularization with autologous veins.