Comparing techniques: the use of recalcified plasma in comparison with citrated plasma alone and in combination with thrombin in ultrastructural studies.

Fibrin plays a vital role in the coagulation process and fibrin fiber morphology can be studied using ultrastructural techniques. When studying the ultrastructure of fibrin networks, thrombin may be added to the plasma, ensuing fibrin network formation. The question that arises is whether there are differences in morphology when thrombin is added to plasma, versus morphology observed when plasma from citrated or recalcified citrated whole blood, is studied. The current study therefore aimed to compare ultrastructure of platelets and fibrin networks from these three techniques. Results indicated comparable platelet ultrastructure between smears formed from the plasma of citrated blood and that of the citrated recalcified blood. This method might give us further information regarding the 'natural state' fibrin assembly and association with platelets, when studying haemostasis. However, when studying the ultrastructure of fibrin networks, the addition of thrombin is necessary to form an expansive, fully coagulated layer of fibrin fibers.

ROTEM analysis: a significant advance in the field of rotational thrombelastography.

At the turn of the century, a significant advance in the rapidly expanding field of rotational thrombelastography (ROTEG), known at present as thrombelastometry or ROTEM analysis, was developed at the Ludwig-Maximillian University in Munich. The measuring unit is operated by a laptop computer. There are four temperature-controlled measuring channels in which the global assays not only detect coagulation factor defects but also platelet function, abnormal fibrinogen polymerisation, anticoagulant defects and hyperfibrinolysis. ROTEM has steadily increased in popularity, particularly because of its well-established application as a diagnostic aid at the point of care in the critical care situation. It also provides a useful guide in the choice of an appropriate therapeutic option in the bleeding patient, reducing costs by avoiding administration of costly component therapy such as fresh-frozen plasma, cryoprecipitate, platelet concentrates or antifibrinolytic agents. As well as being useful in monitoring anticoagulant therapy and the use of pharmacological agents, ROTEM is a valuable research tool in the field of hypercoagulability, fibrinolysis, factor XIII activity and the ultimate phases of the blood coagulation process.

Investigating the ultrastructure of platelets of HIV patients treated with the immuno-regulator, Canova: a qualitative scanning electron microscopy study.

The resistance of HIV strains to the available antiretroviral medication has become a major problem in the world today. This has forced researchers to investigate the possible use of alternative drugs such as homeopathic medicine (e.g. immunomodulators) to enhance the immune system of patients infected with HIV. Canova is an immunomodulator of herbal origin which is known to stimulate the host defense against several pathological states through the activation of the immune system. Blood platelets play an important role in homeostasis, thrombosis and the immune response by forming platelet aggregates. The ultrastructure of platelet aggregates of patients with HIV has been studied previously using SEM to determine the effect of HIV on the platelet morphology. Membrane blebbing and ruptured platelet membranes were observed which is indicative of apoptosis, revealing that HIV patients may develop thrombocytopenia as a result of peripheral platelet destruction. The aim of the current study was to investigate the effect of HIV on the morphology of platelets from patients treated with the immuno-modulator, Canova, compared to control individuals and HIV patients not on the Canova treatment. Blood was drawn from the individuals and the coagula were formed by adding human thrombin to the platelet rich plasma. Examination was done using SEM. CD4 counts were also determined. Slight morphological changes were seen when comparing the fibrin networks from the control, untreated HIV patients and the Canova-treated HIV patients, suggesting that HIV does not impact on the fragility of fibrin networks. In HIV patients there are bleb-like bulges on the membrane of platelets as well as membrane breakages visible on the aggregate, whereas in the Canova-treated patients membrane blebbing is far less pronounced and there are large areas of intact, smooth membranes with visible canalicular areas, suggesting that Canova protects the membranes of platelets and that blebbing does not appear in such great proportions as was found in the untreated HIV group. These results support and provide ultrastructural evidence for the results seen in previous research, where it is seen that Canova protects the immune system of immuno-compromised patients by keeping the ultrastructure intact thereby preventing the devastating cyto-destructive effects of HIV disease.

Proximal great saphenous vein cut down: an evaluation of techniques and anatomical considerations.

Cut-down techniques by which emergency venous access can be achieved are important, particularly, in the resuscitation of haemodynamically depleted patients where percutaneous access to collapsed veins is a problem. The aim was to evaluate the efficacy of different methods that are used to locate the proximal great saphenous vein in the thigh and to describe the vein's immediate course. A further component was to identify the position of the valves in the proximal great saphenous vein. Needles were placed in 42 cadaver thighs as defined by the techniques identified from the literature and surgical practice. After a detailed dissection, the vein's relation to these needles was measured and the course of the vein and number of valves noted in relation to easily identifiable landmarks. Landmarks in 2.5-cm intervals on a line from the pubic tubercle to the adductor tubercle of the femur were used. The rule of two's, an experimental method by one of the authors, along with Dronen's second method localized the vein most successfully. The course of the vein was scrutinized and found to have a rather direct course as it proceeded medially toward the saphenous hiatus. The largest population of valves could be found in the proximal 5 cm (76%) with a valve in the confluence of the great saphenous vein and the femoral vein being the most common. Valve populations were found to decrease in number from proximal to distal, which would have implications with the placement of catheters into the vein for fluid resuscitation.

The sternocleidomastoid myoperiosteal flap for the reconstruction of a tracheal defect.

The sternocleidomastoid (SCM) myoperiosteal flap offers a relatively simple, single-stage reconstruction of a tracheal defect after conservative resection of an invasive papillary cancer of the thyroid with intraluminal involvement. Vascularised clavicular periosteum provides a viable, pliant, airtight, composite autologous graft with minimal vocal disturbance and a low risk to the parathyroid glands. The operation is not difficult to perform and has an acceptable long-term result even for the occasional operator in the specialised field of tracheal surgery.

Structural changes in the fibrin network of a pretoria family with dysfibrinogenemia: a scanning electron microscopical study.

Inborn errors of fibrinogen structure are by definition congenital dysfibrinogenemias. The present study assesses the scanning electron microscope characteristics in the fibrin network morphology in a Pretoria family with an amino-acid substitution defect at position 139 on the gamma chain where the cystein residue is replaced by tyrosine. This anomaly results in a disturbance of the interchain disulfide bond, an ultrastructural defect that interferes with fibrin polymerization. Clinical manifestations showed that 2 of the family members presented with thrombosis, as well as a bleeding tendency, while 2 were asymptomatic. Fibrin clot analysis revealed that in all 4 family members a tighter fibrin network with increased fibrin density and reduced pore size was present. The fibers showed a "stellate" appearance where they converge and some were fused longitudinally to form sheets of "matted" fibrin. Furthermore, there was a conspicuous absence of platelets. Fibrin dysfunction is associated with the development of vascular complications, while proneness to the formation of tight and rigid fibrin networks is independently associated with thrombotic disease. Although this does not explain the proneness of some family members who present with excess bleeding, bleeding might be related to the defective binding of fibrin to activated platelets, resulting in inadequate prothrombotic stimulus that is normally enhanced by the second wave of thrombin generation, which occurs on the platelet surface.

Sigmoid colon vaginoplasty: a modified method.

OBJECTIVE: To assess the technical feasibility and functional results of sigmoid colon vaginoplasty using a modified technique. DESIGN: Retrospective descriptive analysis. SETTING: Referral centre. PATIENTS: A method for creating an artificial vagina was applied in 13 women for the following indications: true hermaphrodite (n = 1), gender dysphoria (n = 2), Müllerian dysgenesis (n = 10). INTERVENTIONS: A method for sigmoid vaginoplasty was devised whereby transection of the inferior mesenteric artery proximal to the first sigmoid branch provides immediate mobility for the sigmoid colonic segment to reach the introitus (with adequate nourishment from the middle and inferior rectal vascular systems). MAIN OUTCOME MEASURES: Assessment of sexual function after a follow up period of 1 to 19 years. RESULTS: Twelve women reported a satisfactory result. Three of these were lost to follow up after one year, and the others report for regular assessment. Mild stenosis at the muco-cutaneous anastomosis, which may occur after failed perineal procedures, appears to be amenable to daily dilatations until the women become sexually active. In one woman the prosthesis had to be removed on account of severe pelvic floor fibrosis as a result of previous abdomino-perineal surgery at the age of seven. Another woman presented with a postcoital vesico-vaginal fistula after a previous McIndoe procedure; the tear at the base of the bladder was repaired and buttressed with a sigmoid vagina which is now functioning satisfactorily after 19 years. CONCLUSION: The creation of a sigmoid vagina which is vascularised by the middle and inferior rectal arterial systems appears to be an acceptable procedure for vaginal agenesis, acquired vaginal loss or sexual reassignment.

Mechanism of thrombosis caused by sclerotherapy of esophageal varices using sodium tetradecyl sulphate.

The mechanism of thrombosis following intravariceal injection of sodium tetradecyl sulphate (S.T.D.) was investigated with respect to effects on the vascular endothelium, the coagulation cascade, and platelet function. Using an umbilical cord model designed to simulate blood flow over the endothelium, it was found that S.T.D. is a potent toxin for endothelial cells in that brief exposure to even low concentrations of the agent were effective in stripping endothelium over a considerable distance, exposing highly thrombogenic endothelium in the process. Effects on coagulation and platelet function were found to be dependent on concentration. Diluted S.T.D. induced a hypercoagulable state, possibly in consequence of a selective inhibition of the physiological anticoagulant, protein C, and promoted platelet aggregation. Higher concentrations inactivated the coagulation cascade and lysed platelets completely. These results suggest that intravariceal infusion of S.T.D. at considerable dilution may be at least as effective in inducing thrombosis as standard dosage, and possibly more so.

The effect of calcium and magnesium ions on urinary urokinase and sialidase activity.

The effect of a promoter (calcium) and an inhibitor (magnesium) of urolithiasis was spectrophotometrically studied on urokinase (0.45 IU) and sialidase (5 mM). Although these mineral did not affect the sialidase activity, total inhibition of urokinase activity was observed with either 0.05 M calcium chloride or 0.1 M magnesium chloride. This observation might explain why calcium and magnesium respectively function as a promoter and an inhibitor of stone formation.

Television image of a large upward electrical discharge above a thunderstorm system.

An image of an unusual luminous electrical discharge over a thunderstorm 250 kilometers from the observing site has been obtained with a low-light-level television camera. The discharge began at the cloud tops at 14 kilometers and extended into the clear air 20 kilometers higher. The image, which had a duration of less than 30 milliseconds,resembled two jets or fountains and was probably caused by two localizd electric charge concentrations at the cloud tops. Large upward discharges may create a hazard for aircraft and rocket launches and, by penetrating into the ionosphere, may initiate whistler waves and other effects on a magnetospheric scale. Such upward electrical discharges may account for unexplained photometric observations of distant lightning events that showed a low rise rate of the luminous pulse and no electromagnetic sferic pulse of the type that accompanies cloud-to-earth lightning strokes. An unusually high rate of such photometric events was recorded during the night of 22 to 23 September 1989 during a storm associated with hurricane Hugo.

Acute acalculous cholecystitis in critically ill patients. Case reports.

Five cases of acute acalculous cholecystitis complicating trauma or an existing major illness are reviewed. This condition differs from classical cholecystitis in many aspects. It is serious and often fatal (3 of our patients died) with multifactorial pathogenesis. Clinical signs and laboratory investigations may be difficult to interpret because of associated conditions. Serial ultrasound examinations in high-risk patients in whom the disease is suspected should lead to earlier diagnosis. Early cholecystectomy is mandatory.

Effect of single dose aspirin on the development of penile hypercoagulability during erection.

The effect of aspirin on the development of hypercoagulability in the penile blood during erection was studied in five Chacma baboons. Aspirin prevented the generation of hypercoagulability and may be of importance in delaying the development of penile atherosclerosis and ageing impotence.