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Biomedical subjects

M Davis

Publications and source records attributed to M Davis.

At least 595 records · Page 33Linked to original sources
PubMed1980

Lymphocyte cytotoxicity to halothane altered hepatocytes in patients with severe hepatic necrosis following halothane anaesthesia.

Lymphocytes from three of four patients with severe unexplained hepatitis following halothane anaesthesia were cytotoxic in vitro for liver cells isolated from rabbits following halothane anaesthesia, and less so for control hepatocytes. While the latter reaction could be blocked by addition of a purified liver membrane lipoprotein (LSP), this had no effect on the cytotoxicity to "halothane" hepatocytes. These results provide evidence that patients with severe halothane-associated hepatitis are sensitised to a liver cell antigen distinct from LSP, which arises as a result of halothane anaesthesia.

Adult↗
PubMed1979

Tryptophan-free diet: effects on the acoustic startle reflex in rats.

In Experiment 1, body weights of rats fed a powdered tryptophan-free (TF) diet decreased monotonically during a 13-day period. Control animals fed the same diet supplemented with 0.5% L-tryptophan gained weight. The groups did not differ significantly in acoustic startle amplitude measured at 2, 4, 6, 7, 9, 11, and 13 days despite a 28% decrease in whole-brain serotonin in the TF rats. In Experiment 2, daily intubation of rats with a syrup form of each diet maintained the two groups' body weights at comparable levels. TF diet intubation decreased whole-brain serotonin by 64% and produced significantly elevated startle amplitudes, which returned to control levels when 0.5% L-tryptophan was added to the diet. Changes in whole-brain serotonin level preceded changes in startle amplitude by several days. In Experiment 3, acute injections of 125 mg/kg L-tryptophan significantly reduced the startle amplitude of TF diet intubated rats and significantly raised their brain serotonin levels. The results show that acoustic startle reflex is increased by a TF diet, provided the animals receive adequate nourishment, and suggest that this facilitation may result from depletion of brain serotonin.

Acoustic Stimulation↗
PubMed1979

Diazepam and flurazepam: effects on conditioned fear as measured with the potentiated startle paradigm.

Diazepam (0.3, 0.6, 1.2, or 2.5 mg/kg) produced a dose-dependent reduction of the potentiated startle effect where acoustic startle amplitude is normally increased in the presence of a light previously paired with a shock. Even the lowest dose tested (0.3 mg/kg) significantly attenuated potentiated startle. The effect was selective since the same doses did not depress baseline startle amplitude measured in the same animals in the same test session. A 2 X 2 design in which rats were trained and tested under the same or different drug condition (diazepam or saline) showed the results could not be explained by state-dependent learning. The primary effect of diazepam was to block expression of rather than acquisition of fear as measured by potentiated startle. Flurazepam (2.5, 10, or 20 mg/kg) also reduced potentiated startle selectively but was 6--8 times less potent than diazepam. These and other results suggest that the potentiated startle paradigm, as a measure of classical conditioning that involves no operant, might provide a useful adjunct to behavioral methods currently being used to analyze antianxiety compounds.

Animals↗
PubMed1979

Morphine and naloxone: effects on conditioned fear as measured with the potentiated startle paradigm.

Morphine (0.6 to 10 mg/kg) produced a dose-dependent reduction of the potentiated startle effect where acoustic startle amplitude is normally increased in the presence of a light previously paired with a shock. The effect was selective since the same doses did not appreciably depress baseline levels of startle. Naloxone (2 mg/kg) did not significantly affect potentiated startle, but antagonized the ability of morphine (10 mg/kg) to block potentiated startle. Morphine did not block potentiated startle by accelerating extinction. The advantages of this paradigm for studying fear or anxiety were discussed.

Animals↗
PubMed1979

Noradrenergic agonists and antagonists: effects on conditioned fear as measured by the potentiated startle paradigm.

Clonidine (10-40 microgram/kg) produced a dose-dependent reduction of fear as measured by the potentiated startle effect (increased acoustic startle in the presence of a cue which had been previously paired with shock). The reduction of potential startle could not be accounted for entirely by a general depressant effect of clonidine on startle nor by an acceleration of extinction. Piperoxane and yohimbine, which are associated with anxiety in humans, increased potentiated startle, whereas propranolol and WB-4101 did not. These results provide further evidence that the potentiated startle paradigm in the rat is sensitive to drug that alter anxiety in humans. Moreover, they support the hypothesis that norepinephrine transmission is important for the expression of fear or anxiety.

Animals↗
PubMed1979

Changes in plasma lipoproteins accompanying diet therapy in obese diabetics.

Plasma lipoprotein cholesterol and triglyceride levels were measured in 24 obese not-insulin dependent Pima Indian diabetics and 9 obese nondiabetic controls before and after 1-8 months on a 500 calorie diet. The diabetics were divided into 3 groups--severe, recent onset (n = 10), severe long-term (n = 6), and borderline (n = 8). The diet regimen resulted in weight loss and improved glucose tolerance in all of the diabetics, and insulin secretion increased in the 2 groups of severe diabetics. After the period of weight loss, total plasma cholesterol had declined greater than 20%, and LDL cholesterol decreased 25% in all diabetic groups and in the controls. In all diabetic groups, HDL cholesterol did not decline; therefore the ratio of HDL/LDL cholesterol after diet therapy was significantly increased. In the controls HDL cholesterol declined with weight loss, and the distribution of HDL/LDL cholesterol remained constant. Plasma and VLDL triglyceride levels decreased in all groups in those with initial triglyceride levels greater than 150 mg/dl. The results indicate that weight loss in not-insulin dependent diabetics not only improves glucose tolerance, but also lowerss plasma lipids and reverses the dyslipoproteinemia often associated with this disorder. This may influence the risk of arteriosclerotic heart disease in these individuals.

Adult↗
PubMed1979

Comparison of the reaction to Dharmendra antigen in the normal skin and in the lesion of leprosy patients.

In this study 0.1 ml of Dharmendra antigen was injected intradermally into the normal skin and lesions of 35 leprosy patients. The response was measured at 24 hrs., 48 hrs. and 21 days. It was found that the maximum response to Dharmendra antigen occurred at the end of 24 hrs. and started wanning by 48 hrs. In tuberculoid leprosy, there was significantly greater response in the lesion as compared with the nearby normal skin. It has been suggested that this could reflect an increased immunological activity at the site of the lesion. In the borderline tuberculoid cases with annular lesions, Dharmendra antigen was injected into the peripheral infiltrated area and into the apparently normal centre of the lesion, and a greater response was found at the centre. This might be the site of a previous lesion. The late reaction at the end of 21 days did not show much significant difference.

Humans↗
PubMed1979

Purification of rabbit antispermine antiserum by affinity chromatography.

Immunoglobulins G were isolated from a crude rabbit antispermine antiserum using a protein A-Sepharose CL-4B column. Affinity chromatography coupling spermine to the Sepharose matrix was employed for separation of antispermine antibodies from these immunoglobulins. Four fractions of antispermine antibodies were isolated by stepwise elution with solutions at pH range from 4 to 1. Binding constants were determined and cross-reactivity with other polyamines was tested for each fraction of antibodies. Highly specific antispermine antibodies were found in fraction IV.

Animals↗
PubMed1979

Dietary management of patients with diabetes treated by hemodialysis.

Early experience with the treatment of patients with insulin-dependent diabetes and renal failure by chronic hemodialysis indicated a high mortality and increased incidence of medical complications. Since 1972, a marked improvement in survival and reduction in incidence of complications has been attributed to more rigorous control of fluid overload, hypertension, and blood sugar levels by insulin therapy and careful dietary management. A diet has been developed which combines the diet used by dialysis patients with suitable modifications for the insulin-dependent patient with diabetes. The importance of patient education is stressed in an attempt to improve patient compliance.

Diabetes Mellitus↗
PubMed1979

Intracranial pressure in pigs with surgically induced acute liver failure.

Cerebral edema has now been noted to occur frequently in patients dying of fulminant hepatic failure. In the present study, intracranial pressure was monitored in an animal model of acute liver failure. Acute liver failure was induced surgically by hepatic devascularization. Serial monitoring of the electroencephalogram revealed progressive slowing of the frequency with decreasing amplitude. Elevation of the blood ammonia was also observed from baseline values of 64 +/- 12 SE to 744 +/- 97 mumol/liter. Monitoring of the intracranial pressure with a subdural pressure transducer demonstrated a progressive and reproducible rise from 12.8 +/- 2.5 mm Hg immediately after the operation to a mean value of 51.6 +/- 11.8 mm Hg just before death 6--12 hr later. At autopsy, the brains of the test animals were found to be swollen with flattened cortical gyri. In the control animals, intracranial pressure rose slightly but returned toward normal levels (8.0 +/- 2.5 mm Hg) 8 hr after laparotomy and remained normal until their death. There was a statistically significant difference between intracranial pressure levels of the test animals and those of the controls (P less than 0.01). Intravenous methylprednisolone (2.0 g initially followed by 0.5 g every 2 hr) administered immediately before and after hepatic devascularization prevented rises in intracranial pressure but had no effect when given 4 hr after operation. The early and progressive increase in intracranial pressure was an unexpected finding, and an assessment of such a sequence in patients with fulminant hepatic failure is currently in progress.

Animals↗
PubMed1978

Sensitisation to halothane-altered liver components in severe hepatic necrosis after halothane anaesthesia.

In-vitro sensitisation (inhibiton or stimulation of leucocyte migration) in response to a liver homogenate obtained from rabbits pretreated with halothane was found in eight of twelve patients with halothane-associated hepatitis. Sensitisation was not observed when the homogenates were obtained from animals pretreated with ether. Furthermore, leucocyte migration in response to "halothane homogenate" was normal in eleven patients who had shown no abnormality in liver function after halothane anaesthesia and in thirty patients with other liver diseases. These studies provide direct evidence that sensitisation to halothane-altered liver-cell components is present in those occasional patients in whom severe liver damage develops after halothane anaesthesia.

Adult↗
PubMed1978

Water-soluble vitamins in severe liver disease.

Biochemical deficiency of thiamine, vitamin B6, ascorbic acid or nicotinic acid occurred in 71% and 88% of patients with fulminant hepatic failure (FHF) and decompensated chronic liver disease (DCLD) respectively. Transient high plasma vitamin B6 concentrations in FHF were followed by low levels later in the illness. Although patients with DCLD of alcoholic aetiology tended to have lower circulating levels of vitamins than those with non-alcoholic DCLD, the prevalence of abnormally low concentrations did not differ. Decreased dietary nutrient intake and alcohol appeared to be less important determinants of biochemical vitamin deficiency than the presence of liver disease per se. Finally, urinary excretion of these vitamins or their major metabolites in patients with severe liver disease correlated poorly with circulating levels of vitamins.

Ascorbic Acid↗
PubMed1978

[1-14C]Ethanol breath test in alcoholic liver disease.

The activity of ethanol metabolising enzymes was assessed in 51 patients with alcoholic and non-alcoholic liver disease using tracer doses of [1-14C]ethanol and measuring 14CO2 excretion in the breath. Alcoholic patients with only fatty infiltration of the liver showed significantly increased activity compared with controls. Comparing alcoholic patients with cirrhosis and a serum albumin greater than 28 g/l, activity in those with a recent history of continued heavy drinking was significantly greater than in patients who had abstained from alcohol. In addition, both groups of alcoholic cirrhosis showed significantly more activity than patients with non-alcoholic cirrhosis. The activities of patients with acute alcoholic or viral hepatitis were normal when their prothrombin times were less than 7 sec prolonged, but were reduced when prolongation exceeded 7 sec. These results demonstrate that in chronic alcoholic liver disease, even with cirrhosis, alcohol can still increase the activity of ethanol oxidising enzymes provided hepatic function remains adequate. However, this response is lost in acute liver damage and in chronic alcoholic disease with severe hepatic dysfunction.

Albumins↗
PubMed1978

Vitamin B6 and aspartate aminotransferase activity in chronic liver disease.

Serum aspartate aminotransferase (AST) concentrations are commonly determined to detect hepatocellular damage. However, discrepancies between serum AST values and histological signs of active liver damage sometimes occur in patients with cirrhosis. The enzyme AST requires pyridoxal-5-phosphate (PLP) (active vitamin B6) as a co-enzyme to express its activity. Since approximately 90% of patients with severe cirrhosis are vitamin B6-deficient, it has been suggested that vitamin B6 supplements given to these patients might cause an elevation of falsely low serum AST concentrations. Treatment of 8 vitamin B6-deficient cirrhotic patients with pyridoxine hydrochloride (50 mg intravenously twice daily for 1 week) increased their serum AST concentrations from 121 +/- 18 (mean +/- SEM) to 136 +/- 26 lU/l, while treatment of a second group of 9 patients with the active co-enzyme PLP increased AST concentrations from 118 +/- 17 to 146 +/- 20 lU/l. Neither of these increases was statistically significant. Plasma PLP increased from 2,4 +/- 0,7 to 18,5 +/- 7,6 ng/ml after pyridoxine, and from 3,3 +/- 0,7 to 27,0 +/- 6,2 ng/ml after PLP supplementation. It is concluded that B6 deficiency is unlikely to be an important determinant of serum AST concentrations in patients with chronic liver disease.

Aspartate Aminotransferases↗