Effects of progesterone on some brain neurotransmitters in intact rats.

Effects of progesterone on four neurotransmitters (viz, noradrenaline, 5-HT, dopamine and histamine) of brain were seen in rats with intact ovaries. It was found that progesterone lowers the noradrenaline concentration in medulla, pons, midbrain, hypothalamus, thalami and pituitary, uniformly, when the rats were killed within 4 hours of progesterone injection. At longer intervals (48 hrs) effects of progesterone were seen when progesterone in heavy dose was administered to rats pretreated with estrogen. It is likely that one of the modes of action of the oral contraceptives may be the reduction of noradrenaline content in selected areas of brain, by progesterone. It is also suggested, therapeutic usage of progesterone carries the risk of development of depression in the user.     

Protection against 7,12-dimethylbenzanthracene-induced tumour initiation by protein A in mouse skin.

Protein A is an immunostimulating glycoprotein obtained from Staphylococcus aureus Cowan I. Its antitumour activity is proven in various tumour models. Its ability to provide protection against tumour initiation by the chemical carcinogen 7,12-dimethylbenzanthracene (DMBA) has been investigated in the present study using a mouse skin model of two-stage carcinogenesis. Protein A was administered intraperitoneally (1 microgram/animal 20 g body wt.) twice a week for 2 weeks, prior to initiation by DMBA. The promotion was performed by twice weekly applications of 12-O-tetradecanoyl phorbol-13-acetate (TPA) (3 or 5 micrograms/animal in 100 microliters acetone). Protein A provided significant protection to animals from DMBA-induced tumour initiation as was observed by the decrease in cumulative number of tumours, percent of animals developing tumours, number of tumours per animal and rate of tumour growth. Our data indicate that protein A has anticarcinogenic properties.     

THE IMPACT OF PRE-CLERKING CLINICS ON SURGICAL OPERATION CANCELLATIONS: A PROSPECTIVE AUDIT

Pre-clerking of all patients undergoing elective general surgical operations was introduced at our hospital in an attempt to reduce an unacceptably high operation cancellation rate. A prospective audit has been performed on the effect of this policy on the cancellation rate. Before the introduction of pre-clerking there was a marked seasonal variation in the number of patients who failed to attend for surgery, which could be explained by absence on holiday. This seasonal variation disappeared after the start of pre-clerking clinics, but there has been no reduction in the number of cancellations for medical reasons.     

Mixed venous oxygen saturation in abdominal aortic surgery: intraoperative hypothermia and vasodilator therapy implications

This prospective study was designed to test the hypothesis that intraoperative hypothermia occurring during abdominal aortic surgery and vasodilator therapy used to avoid severe consequences of aortic clamping could both disturb the mixed venous oxygen saturation signal (SVO2). Twenty high risk surgical patients, ASA physical status II or III, were catheterized with the standard pulmonary artery catheter; SVO2 was determined by direct spectrophotometric measurements of oxygen haemoglobin concentration of serial samples. The relationships between SVO2, haemodynamic, metabolic variables and core temperature were analyzed. Haemodynamic values and oxygen transport were stable while inadequate tissue oxygenation occurred. A significant correlation was found between SVO2 and CI (r = 0.59, p less than 0.01), SVO2 and SVRI (r = -0.4, p less than 0.01), SVO2 and CT (r = -0.46, p less than 0.01), SVO2 and VO2 (r = -0.76, p less than 0.001). SVO2 and Qs/Qt (r = 0.83, p less than 0.001), SVO2 and EO2 (r = -0.75, p less than 0.001. No correlation was observed between SVO2 and lactacidemia (r = 0.04, p less than 0.05). Satisfactory haemodynamic stability and oxygen transport steady-state were the main conditions for a significant correlation between SVO2 and haemodynamic factors. However, there was no correlation between SVO2 and inadequate tissue oxygenation. SVO2 reflected only oxygen extraction. Intraoperative hypothermia provided an increased haemoglobin affinity for oxygen. Vasodilator therapy which allowed a decrease in systemic vascular resistance produced an increase in the left-right shunt and in venous oxygen admission. Thus hypothermia and vasodilator therapy could be both responsible for the elevated SVO2 occurring during infrarenal abdominal aortic surgery.     

New Latex Bead Agglutination Assay for Differential Diagnosis of Cattle Infected with Mycobacterium bovis and Mycobacterium avium subsp. paratuberculosis

Extensive studies have shown that the current assays used to identify cattle infected with Mycobacterium bovis or Mycobacterium avium subsp. paratuberculosis are not sufficiently sensitive and specific to detect all infected animals, especially animals recently infected with the pathogens. In the present report we show that these limitations might be overcome with a latex bead agglutination assay (LBAA). With the specific immunodominant epitope (ESAT6-p) of M. bovis, we developed an LBAA and enzyme immunoassay (EIA) for that purpose and compared them with the “gold standard” culture method and skin test for their efficacy in detecting bovine tuberculosis. When sera from control healthy cows (n = 10), M. avium subsp. paratuberculosis-positive cattle (naturally infected, n = 16; experimentally infected, n = 8), and M. bovis-positive cattle (naturally infected, n = 49;experimentally infected, n = 20) were applied to an EIA and an LBAA developed with ESAT6-p, the two tests showed similar sensitivity (97.1% by EIA, 95.7% by LBAA), high specificity (94.2% by EIA, 100% by LBAA), and a positive correlation (kappa value, 0.85; correlation rate, 93.2%; correlation coefficient, 0.64). Receiver operating characteristic analysis of EIA results and comparison with the culture method determined a suitable cutoff value at 0.469, with an area under the curve of 0.991 (95% confidence interval, 0.977 to 1.0). As LBAA didn't show any positive reactions with sera from uninfected control cows or M. avium subsp. paratuberculosis-infected cattle, which were confirmed to be free of M. bovis by culture or PCR, LBAA using the ESAT6-p can be a rapid and useful M. bovis diagnostic assay. The data suggest that rapid, sensitive, and specific assays can be developed with peptides containing immunodominant epitopes present in proteins uniquely expressed in M. bovis or M. avium subsp. paratuberculosis for differential diagnosis of cattle infected with M. bovis or M. avium subsp. paratuberculosis.     

Suppression of canine antral gastrin secretion by urine

Distention of the gastric antrum with an alkaline fluid normally results in the secretion of gastrin. Following gastrocystoplasty in humans, however, hypergastrinemia has not been observed. We explored the possibility that a component of urine may suppress antral gastrin activity in the dog. Partial cystectomy and antral transposition to the bladder (ATB) was performed in five animals and antral transposition to the colon (ATC) was performed in five other dogs to serve as a hypergastrinemic controls. At four and eight weeks after surgery the mean serum gastrin levels in the ATC dogs were significantly greater than the mean preoperative levels (p less than 0.05). In contrast, at four and eight weeks after surgery the mean serum gastrin levels in the ATB animals were significantly less than the mean preoperative levels (p less than 0.05). The antral G-cell density as determined by immunohistochemical study at eight weeks after surgery was greater than normal in the ATC dogs but less than normal in the ATB dogs; but the differences did not achieve statistical significance. In another series of experiments using four other dogs a 4% aqueous peptone solution and a 4% peptone solution in concentrated dog urine were instilled into exteriorized antral pouches. The mean serum gastrin levels at 60 and 90 minutes after instillation of the former were significantly increased (p less than 0.05), but there was little or no change after instillation of the latter. Urine, or a component of urine, appears to suppress canine antral gastrin secretion and may explain the absence of hypergastrinemia following gastrocystoplasty in humans.