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Biomedical subjects

M Johnson

Publications and source records attributed to M Johnson.

At least 703 records · Page 39Linked to original sources
PubMed1985

What is the appropriate control for the tilt illusion?

Recently it has been suggested that when tilt illusions are measured by parallel matching to the test arm of an acute angle, the usual control condition involving a match to the test arm in the absence of the inducing arm is inappropriate. According to Hotopf et al this is so because the pretest contains a second, depth-based illusory effect which is not contained in the test conditions. Whereas Hotopf et al gave indirect evidence for this claim, direct evidence is presented here for their assertion. The results suggest that there is no single stimulus configuration which could serve as a pretest control for all tilt illusion stimuli. Rather, the condition in which the test and inducing lines intersect at 90 degrees probably is the appropriate control for all other inducing-test-line angle displays.

Depth Perception↗
PubMed1985

The influence of single dose intravenous antibiotics on faecal flora and emergence of Clostridium difficile.

The influence of a single intravenous dose of antibiotic on faecal flora and the emergence of Clostridium difficile was studied in volunteers. Seventy-eight volunteers (13 groups of 6 receiving 5 penicillins and 8 cephalosporins) were given a single intravenous dose of antibiotic. Results were compared with a control group of 6 volunteers who did not receive an antibiotic. Changes in the faecal flora were monitored over two weeks. Only cephalosporins were associated with emergence of Cl. difficile, penicillins and controls were not. Frequency of emergence of Cl. difficile in the 6 volunteers in each of the cephalosporin groups were as follows: cephaloridine 0, cephazolin, 1 cefuroxime 1, cefoxitin 2, cefotaxime 2, latamoxef 3, ceftriaxone 2, cefotetan 4. Latamoxef (moxalactam) was associated with a significant rise in total aerobic bacterial counts largely due to increased counts of enterococci. Cefotetan eliminated Escherichia coli and Bacteroides fragilis from the faecal flora three days after administration.

Anti-Bacterial Agents↗
PubMed1985

Defective renal prostaglandin synthesis in hypertensive patients with morbid obesity.

Renal prostaglandin synthesis in 36 obese hypertensive patients was estimated from measurements of 24-hour urinary prostaglandin E2 (PGE2) excretion rates. PGE2 was measured by radioimmunoassay using Dray antiserum prior to and 1 week after starting a fast supplemented by 320 cal derived from 30 g of carbohydrate, 45 g protein, and 2 g essential fatty acids. Sodium intake was 120 mEq daily or less. Comparisons were made to a control population of age-matched, nonobese, normotensive, healthy volunteers on a normal diet. Mean weight fell from 260 +/- 8 to 247 +/- 8lb, p less than 0.001. Urinary PGE2 in the obese patients prior to the fast was 104 +/- 27 ng/day, significantly lower than the 404 +/- 124 ng/day found in the control population, p less than 0.005. After the 1st week of the fast urinary PGE2 rose to 213 +/- 55, p less than 0,02. This value was not different from that in the control group. Blood pressure fell (p less than 0.001) in these patients from 143/94 +/- 3/2 to 134/87 +/- 3/2 mm Hg after the 1st week of the fast. Deficient renal prostaglandin synthesis in obese hypertensive patients was corrected by fasting. Such changes in the prostaglandin system may mediate or occur in response to changes in the sodium-volume balance of these patients. These changes in renal prostaglandin synthesis may partly contribute to the blood pressure reduction of these patients.

Blood Pressure↗
PubMed1985

Ethanol-induced water diuresis is not prostaglandin dependent.

Previous studies have demonstrated an effect of alcohol on arachidonic acid metabolism. These studies were undertaken to determine if the water diuresis of alcohol is due to enhanced prostaglandin E2 (PGE2) production, a known antidiuretic hormone antagonist. 6 rabbits, weighing between 2.5 and 3.2 kg, were studied in standard metabolic cages during 4 periods: control, indomethacin administration, ethanol administration, and ethanol and indomethacin. 10 ml of 100% alcohol was added to their water in periods 3 and 4, and 5 mg/kg indomethacin was given during periods 2 and 4. We recorded urine output, urine osmolality, sodium excretion, potassium excretion, and PGE2 excretion. Urine flow rate significantly increased in periods 3 and 4 from 79 +/- 7 to 177 +/- 13 and 165 +/- 11 cm3/day, respectively, p less than 0.001 for both, compared to control. Indomethacin, therefore, did not prevent the water diuresis. Urinary PGE2 excretion was low (125 +/- 13 ng/day) with ethanol administration compared to control (897 +/- 71 ng/day, p less than 0.001). Levels were similar to those seen with the inhibitor indomethacin (105 +/- 22 ng/day, n.s.). These low levels with ethanol were observed at the same time of the significant free water diuresis. We conclude that the water diuresis produced by acute ethanol administration is not mediated by enhanced renal PGE2 production.

Animals↗
PubMed1985

Effects of changes in serum calcium and parathyroid hormone on plasma renin in intact mongrel dogs.

Studies were undertaken to extend previous experiments of the interaction between calcium and parathyroid hormone on renin synthesis by the kidney. Intact normovolemic mongrel dogs between 15 and 25 kg were used for all studies. Plasma renin activity (PRA) was measured by radioimmunoassay. Hypocalcemia produced by thyroparathyroidectomy or chelation with EDTA resulted in an elevated PRA of 3.76 +/- 0.85 ng/ml/h in 17 normotensive dogs compared to 1.52 +/- 0.29 ng/ml/h in 14 normocalcemic normotensive dogs (p less than 0.05). In 5 renovascular dogs, calcium-channel antagonism with nifedipine resulted in a higher PRA of 31.8 +/- 0.5 compared to 11.9 +/- 1.1 ng/ml/h in 23 control renovascular dogs not receiving nifedipine (p less than 0.001). The reactive hyperreninemia following angiotensin blockade was greater in 22 hypocalcemic (10.94 +/- 2.03 ng/ml/h) normotensive dogs compared to 14 normocalcemic normotensive dogs (1.32 +/- 0.34 ng/ml/h, p less than 0.001). Similar results were obtained with angiotensin blockade in nifedipine-treated animals compared to angiotensin blockade in nonnifedipine-treated normotensive dogs. Results with angiotensin blockade on PRA levels in renovascular dogs were found similar to those described with angiotensin blockade in normotensive dogs. We conclude from these studies that calcium reduction, independent of a rise in parathyroid hormone, or calcium-channel blockade was associated with an elevation of PRA in normotensive and renovascular hypertensive dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Accidental and homicidal death in a psychiatric emergency room population.

To identify potentially preventable mortality other than suicide among psychiatric emergency room patients, the authors compared the rates of accidental and homicidal death among 5,284 consecutive psychiatric emergency room patients with those expected for an age-, sex-, and race-matched sample of the general population. The rate of accidental death was two and one-half times and the rate of homicidal death nearly twice the expected rate for the matched general population. Diagnostic and demographic analyses indicated that increased risk of death from either cause was highest among alcoholics, schizophrenic patients, and males. The implications of the findings for clinical care are discussed.

Accidents↗
PubMed1985

Neuropeptide localisation in the substantia innominata and adjacent regions of the human brain.

A dense peptidergic innervation has been demonstrated in the substantia innominata region in postmortem specimens of human brain using immunocytochemical techniques. A peptidergic innervation of the nucleus of Meynert - the prominent nucleus of this area containing the cholinergic cell bodies which innervate the cerebral cortex - has been demonstrated by immunostaining with antisera against the following eight neuropeptides: somatostatin, substance P, cholecystokinin octapeptide, vasoactive intestinal polypeptide, met-enkephalin, ACTH, alpha-MSH and oxytocin. Other immunocytochemical features of the substantia innominata region include a dense band of peptide immunoreactivity beneath the medial aspect of the anterior commissure and islands of somatostatin and substance P terminal immunoreactivity in the rostral part of the substantia innominata. Somatostatin immunostained cell bodies have been located in a discrete area of the bed nucleus of the stria terminalis and in the rostral portion of the substantia innominata, nucleus accumbens and the ventral part of the putamen. The dense band of peptide immunoreactivity beneath the medial aspect of the anterior commissure consists of ribbon-like processes stained with antisera against somatostatin, substance P, cholecystokinin octapeptide, vasoactive intestinal polypeptide and met-enkephalin. Less intense immunostaining of ribbon-like elements is also present in the globus pallidus. The presence of a peptidergic innervation to the nucleus of Meynert suggests a possible important modulatory role in cortical cholinergic function.

Adrenocorticotropic Hormone↗
PubMed1985

Hemoglobin A1 in renal transplant recipients.

Studies were undertaken to determine levels of hemoglobin A1 in renal and heart transplant recipients. Hemoglobin A1 was measured by separation from Hb A using an affinity-column chromatography system. Significantly elevated levels of Hb A1 were found in all renal transplant patients; diabetic transplant recipients had the highest levels. There was no correlation between serum creatinine and Hb A1 levels in these transplant recipients. The Hb A1 level did correlate with the prior level of glycemia in these patients. Our findings raised the specter of the consequences of disturbed carbohydrate metabolism in these patients as not being different than that observed with other forms of end-stage renal disease management. Finally, in both diabetic and nondiabetic renal transplant recipients, measurement of Hb A1 can serve as a useful adjunct to assess prior glycemia when such information is not available to the clinician.

Adult↗
PubMed1985

The incidence of rebleeding in traumatic hyphema.

A collaborative, retrospective study of 371 consecutive hyphema patients reveals an overall 3.5% incidence of rebleeding of without the use of antifibrinolytic agents. Numerous factors were reviewed on each patient, including age, sex, race, grade of hyphema, disposition, and the use of topical or systemic medications. Thirty percent of the patients were treated on an outpatient basis. The low incidence of rebleeding, particularly in less severe hyphemas (less than half the anterior chamber volume), does not support the routine use of systemic antifibrinolytics or corticosteroids.

Adolescent↗
PubMed1984

Incidence of pathogenic bacteria from mesenteric lymph nodes and ileal serosa during Crohn's disease surgery.

Samples of ileal serosa and mesenteric lymph nodes have been harvested before antibiotic administration during 46 non-contaminated operations for Crohn's disease and compared with 43 operations for conditions other than Crohn's. Potentially pathogenic bacteria were isolated from the serosa in 12 (27 per cent) Crohn's patients, compared with 6 (15 per cent) controls (P = 0.04). Intestinal bacteria were recovered from mesenteric nodes in 15 (33 per cent) Crohn's patients compared with 2 (5 per cent) controls (P = 0.006). These findings suggest that bacteria leak from the small bowel lumen in a high proportion of Crohn's disease patients. This may explain the pathogenesis of abscess and fistula in this disorder as well as the high rate of sepsis following elective surgery even in the absence of macroscopic contamination.

Abdomen↗
PubMed1984

The effects of changes in serum calcium and parathormone on plasma renin activity in intact mongrel dogs.

Studies were undertaken to extend previous observations of the interaction between calcium and parathormone on renin synthesis by the kidney. Intact normovolemic mongrel dogs between 15 and 25 kg were used for all studies. Plasma renin activity (PRA) was measured by radioimmunoassay. Hypocalcemia produced by thyroparathyroidectomy or chelation with EDTA resulted in an elevated PRA of 3.76 +/- .86 ng/ml/hr in 17 dogs compared to 1.5 +/- .29 ng/ml/hr in 14 controls (p less than .05). In 5 renovascular dogs calcium-channel blockade with nifedipine resulted in a higher PRA of 31.8 +/- 0.5 compared to 11.9 +/- 1.1 ng/ml/hr in 23 renovascular controls, p less than .001. The reactive hyperreninemia following angiotensin blockade was greater in 22 hypocalcemic (10.94 +/- 2.03 ng/ml/hr) dogs compared to 14 controls (1.32 +/- .34 ng/ml/hr), p less than .001. Results with calcium antagonism on PRA levels in renovascular dogs were found similar to those described with angiotensin blockade. We conclude from these studies that calcium-channel blockade or calcium reduction independent of a rise in parathormone was associated with an elevation of PRA in normal and renovascular hypertensive dogs. The rise in PRA could occur without changes in blood pressure or volume, consistent with an interruption of the short feedback loop control of renin synthesis by calcium antagonism. Finally, hypocalcemia and calcium-channel blockade resulted in reactive hyperreninemia greater than or equal to that seen after angiotensin blockade in both groups of dogs, again suggesting interference with the short feedback loop control of renin synthesis.

Animals↗
PubMed1984

Sodium-dependent lithium ion efflux from murine neuroblastoma and rat glioma cells: a minor pathway for efflux of lithium ions.

Lithium ion efflux by murine neuroblastoma (clone N1E-115) and rat glioma (clone C6) cells was studied to determine the presence of a phloretin-sensitive sodium-lithium countertransport pathway which has been found in human erythrocytes. Although this pathway could be identified in these cultured cells, unlike that in red blood cells, it was a very minor (less than 20%) component of the overall efflux of lithium ions from these cells of nervous tissue origin.

Animals↗
PubMed1984

The analgesic effects of transcutaneous electrical nerve stimulation and placebo in chronic pain patients. A double-blind non-crossover comparison.

The analgesic effects of high frequency transcutaneous electrical nerve stimulation (TNS), "acupuncture-like" TNS and placebo TNS were evaluated in 33 patients with rheumatoid arthritis and chronic hand pain using a randomized, double-blind, non-crossover design. An oscilloscope was employed to monitor the stimulator output in the TNS treatment groups and to provide strong suggestion and a focus of attention in the placebo treatment group. The two forms of TNS were applied at the highest intensity that could be tolerated by patients. Assessments of resting pain, joint tenderness, grip strength and grip pain were made before and after treatment. The pain and joint tenderness measurements showed high frequency TNS, "acupuncture-like" TNS and placebo TNS to be equally effective in producing analgesia of similar degree and trend over time. The grip strength measurements showed no significant change. The results obtained with placebo are probably due to the suggestion and attention effects of the visual stimulus. The implications of these results in respect to pain control pathways are discussed. Although TNS given at high intensity was shown to be no better than placebo applied with strong suggestion, this does not preclude its use as a method of pain control in rheumatoid arthritis.

Acupuncture Therapy↗