Collagenase and tissue plasminogen activator production in developing rat calvariae: normal progression despite fetal exposure to microgravity

Exposure to zero gravity has been shown to cause a decrease in bone formation. This implicates osteoblasts as the gravity-sensing cell in bone. Osteoblasts also are known to produce neutral proteinases, including collagenase and tissue plasminogen activator (tPA), which are thought to be important in bone development and remodeling. The present study investigated the effects of zero gravity on development of calvariae and their expression of collagenase and tPA. After in utero exposure to zero gravity for 9 days on the NASA STS-70 space shuttle mission, the calvariae of rat pups were examined by immunohistochemistry for the presence and location of these two proteinases. The ages of the pups were from gestational day 20 (G20) to postnatal (PN) day 35. Both collagenase and tPA were found to be present at all ages examined, with the greatest amount of both proteinases present in the PN14 rats. At later ages, high amounts were maintained for tPA but collagenase decreased substantially between ages PN21 to PN35. The location of collagenase was found to be associated with bone-lining cells, osteoblasts, osteocytes, and in the matrix along cement lines. In contrast, tPA was associated with endothelial cells lining the blood vessels entering bone. The presence and developmental expression of these two proteinases appeared to be unaffected by the exposure to zero gravity. The calvarial thickness of the pups was also examined; again the exposure to zero gravity showed little to no effect on the growth of the calvariae. Notably, from G20 to PN14, calvarial thickness increased dramatically, reaching a plateau after this age. It was apparent that elevated collagenase expression correlated with rapid bone growth in the period from G20 to PN14. To conclude, collagenase and tPA are present during the development of rat calvariae. Despite being produced by the same cell in vitro, i.e., the osteoblast, they are located in distinctly different places in bone in vivo. Their presence, developmental expression, and quantity do not seem to be affected by a brief exposure to zero gravity in utero.     

Scintigraphy with 111In-labeled autologous platelets in venous thromboembolism

Scintigraphy with 111in-labeled autologous platelets was performed in 20 patients with suspected venous thrombosis and/or pulmonary embolism. The platelets accumulated in venous thrombi in 6 or 7 patients (86%) with positive findings on impedance plethysmography or contrast venography; all 6 were receiving intravenous heparin. In 11 patients with pulmonary embolism diagnosed by ventilation--perfusion imaging or pulmonary angiography, platelet scintigraphy showed embolic uptake only in the one patient not on full-dose heparin. These findings suggest that scintigraphy with 111In-platelets is a promising noninvasive technique for detection of deep venous thrombosis. Heparin does not appear to block localization of labeled platelets in venous thrombi, but may inhibit their adherence to pulmonary emboli.     

A clinical trial of a bead bed system for the prevention of pressure sores in elderly orthopaedic patients

This paper summarizes the results of the trial of the Beaufort Bead Bed system designed to reduce the incidence and severity of pressure sores. Elderly orthopaedic admissions were allocated alternately to the Beaufort system and to the usual trolley, table and bed surfaces, and followed from admission to hospital until separation. The incidence of pressure sores was 15.6% in the 32 'trial' patients, which was significantly less than the 48.8% in the 43 'control' patients, as was the mean maximum diameter of the pressure sores incurred: 6.4 mm for the 'trials' as against 29.5 mm for the 'controls'. In particular the trial group were free from pressure lesions to the heel, which affected 32.6% of the control group. The groups were well matched on a variety of criteria on admission, and we conclude that the Beaufort system successfully reduces the incidence and severity of pressure sores for elderly orthopaedic patients. The system--renamed recently the 'Neumark-Macclesfield Support System'--is now in regular and satisfactory use.     

Simultaneous measurement of acetylcholine and choline in brain by pyrolysis-gas chromatography-mass spectrometry

Pyrolysis-gas chromatography and chemical ionization mass fragmentography were combined to develop a specific, simple and rapid method for simultaneously measuring endogenous and stable isotopic variants of acetylcholine and choline with a detection limit of approximately 10(-12) mol. The recovery and reproducibility of the method are excellent, and the method is suitable for measuring acetylcholine and choline in discrete regions of rat brain and to measure incorporation of choline into acetylcholine, both of which uses are demonstrated. This method affords easy analysis of 40 samples in a working day. The new technique used to extract compounds from tissues and the modified gas flow arrangement may be useful to measure other compounds as well.     

Preparation of cryoprecipitated factor VIII concentrates

Factors affecting the yield of factor VIII in cryoprecipitate have been investigated in the context of a blood component program. Both in vitro and in vivo measurements were used to assess the effects of critical variables on the yield of factor VIII activity. Variables such as anticoagulant, plastic bag, mixing during collection, and platelet contamination had no significant effect on yield of factor VIII activity in cryoprecipitate. Among the most critical factors affecting yield were storage time of whole blood and procedures for freezing, thawing, and reconstitution. The following procedures were found to assure a 60 per cent recovery of factor VIII in cryoprecipitate: 1)processing of whole blood within six hours of collection; 2)use of a technique to freeze plasma within 30 minutes either in a -70 C ethanol bath or -85 C freezer; 3)rapid thawing (1 1/2 hour or less) in a 4 C circulating water bath; 4)centrifugation at 4,500 X g for 10 minutes at 4 C followed by draining of the supernatant in a 4 C cold room; 5) storage of the precipitate at -20 C until ready for use; 6) thawing in a 37 C water bath for at least 15 minutes followed by addition of 20 ml of 0.15 M saline for a 20 minute period at room temperature, and gentle mixing before pooling units for transfusion. The recovery of factor VIII in cryoprecipitate appears to be limited to about 65 per cent by its solubility in plasma at 4 C. Therefore, further effort to increase the amount available for treatment should involve improving the supply of plasma for its preparation and decreasing the cost of processing.