Effect of heat or chemical treatment on leptospiral antigens.

The use of bacterins is one of the primary methods in the control of leptospirosis in domestic animals, especially cattle, swine, and dogs. Bacterins have been made using chemically treated or heat-inactivated organisms. Many of the initial studies indicated that the bacterins gave complete protection, whereas later reports found that some inactivation methods resulted in bacterins that protect against death but not against kidney infection and renal shedding. This raised the possibility that some of the antigens had been altered. To investigate this possibility, we heat or chemically treated Leptospira interrogans serovar icterohaemorrhagiae CF-1, L. interrogans serovar canicola Moulton, L. interrogans serovar grippotyphosa SC4397, L. interrogans serovar hardjo Hardjoprajitno, and L. interrogans serovar pomona MLS. Temperatures used to determine alterations in antigens were 50, 56, 80, 100, and 121 degrees C. The chemicals used were formaldehyde, phenol, and thimerosal. Analysis was done using Laemmli gels and Western blots. We found that heating at 50 or 56 degrees C had the smallest effect on antigens, whereas heating at 80 or 100 degrees C caused the appearance of high-molecular-weight bands on Western blots. Heating at 121 degrees C caused almost all the bands to disappear, in both the stained gel and the Western blot. Both phenol and Formalin treatment altered proteins, whereas thimerosal treatment appeared to have little effect compared with heating at 50 degrees C.     

Scalp electrical recording during paralysis: quantitative evidence that EEG frequencies above 20 Hz are contaminated by EMG.

OBJECTIVE: To identify the possible contribution of electromyogram (EMG) to scalp electroencephalogram (EEG) rhythms at rest and induced or evoked by cognitive tasks. METHODS: Scalp EEG recordings were made on two subjects in presence and absence of complete neuromuscular blockade, sparing the dominant arm. The subjects undertook cognitive tasks in both states to allow direct comparison of electrical recordings. RESULTS: EEG rhythms in the paralysed state differed significantly compared with the unparalysed state, with 10- to 200-fold differences in the power of frequencies above 20 Hz during paralysis. CONCLUSIONS: Most of the scalp EEG recording above 20 Hz is of EMG origin. Previous studies measuring gamma EEG need to be re-evaluated. SIGNIFICANCE: This has a significant impact on measurements of gamma rhythms from the scalp EEG in unparalysed humans. It is to be hoped that signal separation methods will be able to rectify this situation.     

Mechanisms responsible for the thermal sensitivity of adrenal microsomal monooxygenases.

Studies were done to determine the mechanism(s) responsible for the thermal lability of adrenal microsomal monooxygenases. Preincubation of guinea pig adrenal microsomal suspensions at 37 degrees C caused large time-dependent declines in benzo(a)pyrene (BP) hydroxylase and benzphetamine (BZ) demethylase activities. Similar preincubations with hepatic microsomes had little effect on enzyme activities. The decreases in adrenal enzyme activities were completely prevented by co-incubation of microsomes with cytosol, but were not diminished by reduced glutathione, ascorbic acid, or bovine serum albumin. Partial protection was afforded by EDTA, suggesting that lipid peroxidation might be involved, but malonaldehyde production was not demonstrable and MnCl2, a potent inhibitor of lipid peroxidation, did not affect the decline in enzyme activities. The decreases in the rates of BP and BZ metabolism were prevented by including NADPH or NADP+ in the preincubation medium. The preincubation conditions causing losses of adrenal enzyme activities did not affect cytochrome P-450 concentrations or substrate binding to cytochromes P-450, as indicated by type I difference spectra. NADH-cytochrome c reductase activity also was not affected, but there were decreases in NADPH-cytochrome c reductase activity that were proportionately similar to the declines in drug-metabolizing activities. Direct assessment of NADPH-cytochrome P-450 reductase revealed similarly large decreases in enzyme activity resulting from preincubation of adrenal microsomes. The results demonstrate a need for extra caution when doing preincubation experiments with adrenal microsomal preparations, and suggest that the thermal lability of adrenal monooxygenases is attributable to effects at the active site of NADPH-cytochrome P-450 reductase.     

Changes in bladder function following a surgical alteration in outflow resistance

The changes in bladder function occurring after a surgical alteration in bladder outflow resistance were studied in 20 males undergoing transurethral prostatectomy (TURP) and in 20 females undergoing an endoscopic bladder neck suspension (EBNS). Serial cystometrograms (CMG) were performed before operation, and on alternate days after spontaneous micturition was re-established, for 5 days in the males and for 21 days in the females. CMGs were repeated at 3 months and 1 year after operation. After TURP voiding pressures (P_det) fell rapidly from a mean of 118 cm H₂O before operation to 57 cm H₂O at 5 days, with an increase in flow rate during this time from 10.5 ml/s to 24 ml/s. Detrusor instability that had been present in 14 patients resolved within 2 days in 12. There was no further significant urodynamic change over the 1-year study period. After EBNS, there was an early rise in voiding pressure (P_det rose from 26 cm H₂O before operation to 42 cm H₂O at 3 days). This continued to increase up to 21 days particularly in those patients with initial large residuals. Three patients developed detrusor instability. Flow rates were greatly reduced at first (27 ml/s before operation and 13 ml/s at 3 days), and gradually increased in line with voiding pressures, yet were still diminished 1 year after operation. The urodynamic changes following a reduction in bladder outflow resistance by TURP are immediate and sustained and unlikely to be the result of structural changes within the bladder wall. EBNS produces an increase in outflow resistance and it can be several weeks before balanced voiding is achieved, with significantly increased detrusor pressures needed to achieve complete bladder emptying at a reduced flow rate.     

Case report 733

Calcific tendinitis at the site of origin of the rectus femoris muscle is a rare lesion. Presumed to be formed by deposition of hydroxyapatite crystals, this entity may be confused with other lesions such as os acetabuli or posttraumatic abnormalities. The characteristic location and appearance of the calcifications in a symptomatic patient with no history of trauma should allow diagnosis and subsequent symptomatic therapy.     

Calciphylaxis – a topical overview

'Calciphylaxis', a calcification syndrome associated with ischaemic cutaneous necrosis, is acquired naturally in humans in disease states. It is a life and limb-threatening complication, usually observed in patients with renal disease and secondary hyperparathyroidism, but known to occur in the absence of renal or parathyroid disease. The reported mortality rate, which ranges from 60-80%, relates to wound infection, sepsis and organ failure. It is a small-vessel vasculopathy, which is estimated to occur in about 4% of haemodialysis patients. Clinically, violaceous, reticulate areas of cutaneous necrosis and eschar may be evident, particularly in the extremities. In addition to the clinical picture, a raised calcium phosphorous product, an elevated parathyroid hormone level, radiographic evidence of vessel and soft-tissue calcification and the finding of mural calcification affecting small arteries and arterioles on histopathology help to confirm the diagnosis of this entity which generally has a poor prognosis. A high index of suspicion and an active multidisciplinary management approach, with rigorous attention to wound care and prevention of sepsis, are vital in the management of these patients. In this overview, we discuss the pathophysiology, clinical features and associations, risk factors, diagnosis and management issues relating to calciphylaxis.