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Biomedical subjects

M Hammer

Publications and source records attributed to M Hammer.

At least 163 records · Page 9Linked to original sources
PubMed1980

The inability of angiotensin II infusions to raise plasma vasopressin levels in haemodialysis patients.

Since it has previously been claimed that angiotensin II (AII) stimulates vasopressin (AVP) secretion, the effect of AII-infusions was studied in 1) 6 normals, 2) 5 non-nephrectomized haemodialysis (HD) patients, and 3) 6 nephrectomized HD patients. In dialysis patients the infusion rate was increased step-wise from 2-12 ng AII/kg bw x min-1 and was terminated if diastolic blood pressure (BP) increased more than 20 mmHg. Normals were infused at a constant rate of 4 ng AII/kg bw x min-1. In all the groups significant increments in BP and plasma aldosterone occurred while plasma renin activity decreased. The plasma vasopressin level was unchanged in normals, while in the two groups of dialysis patients a minor decrease was found. The present study has therefore not been able to confirm a stimulating effect of a physiological dose of AII on AVP secretion, and the results in anephric patients indicate that a normal plasma AII concentration is of no importance for the plasma AVP level.

Adult↗
PubMed1979

Pseudomonas aeruginosa bacteremia: relationship of bacterial enzyme production and pyocine types with clinical prognosis in 100 patients.

Strains of Pseudomonas aeruginosa were studied from 100 patients with bacteremia. In vitro quantitation of extracellular enzymes (lecithinase, protease, and elastase) and pyocine typing of these isolates were performed. No significant difference was found in the quantity of the enzymes produced or in the pyocine types by isolates obtained from patients dying from bacteremia or surviving this serious infection. Quantitation of the extracellular enzymes and pyocine types of blood isolates were contrasted with similar data obtained from sputum, urine, and skin isolates. One third of all strains produced minimal or no extracellular enzymes regardless of their source. However, the highest enzyme-producing strains were observed in the blood isolates. Although a greater variability of pyocine types was found in blood culture isolates, there was no significant difference between the pyocine types found in blood, urine, sputum, or skin isolates. The lack of correlation between the in vitro quantity of lecithinase, protease, and elastase produced by P. aeruginosa strains isolated from bacteremic patients and the prognosis of these patients supports the possible local rather than systemic significance of these extracellular enzymes in the pathogenesis of P. aeruginosa bacteremia.

Extracellular Space↗
PubMed1979

Pseudomonas aeruginosa bacteremia: susceptibility of 100 blood culture isolates to seven antimicrobial agents and its clinical significance.

The susceptibility of 100 blood culture isolates of Pseudomonas aeruginosa observed during 4 1/2 years was tested for tobramycin, netilimicin, gentamicin, amikacin, pirbenicillin, ticarcillin and carbenicillin, singly and in combination. For aminoglycosides, the agar MICs were twofold to threefold greater than tube dilution MICs but for the penicillins they were similar. For aminoglycosides and ticarcillin, the MBCs were twofold greater than the tube dilution MICs. The MBCs were not achieved at concentrations as high as 512 micrograms/ml for 40% of the isolates for pirbenicillin and for 10% for carbenicillin. Tobramycin and pirbenicillin had the lowest MICs for the aminoglycosides and penicillins, respectively. Synergism was tested and observed between tobramycin + ticarcillin and amikacin + ticarcillin. No overall increase in resistance to gentamicin or carbenicillin was seen from 1974 to 1977. However, patients given repeated courses of gentamicin had more resistant strains. Following the administration of 1.5 mg/kg/dose of gentamicin, peak serum concentrations failed to achieve the MIC for the microorganism in 22% of the patients. The MIC was achieved in all patients receiving the same dose of tobramycin. The overall fatality rate was 67% with one third of the patients dying within 36 hr. There was no relationship of patient fatality rate and MIC for the microorganism. Although in the rapidly fatal group of all patients receiving inappropriate therapy died, the fatality rates of appropriately or inappropriately treated patients in the ultimately fatal and nonfatal groups were similar. Underlying host disease was the major determining factor in patient survival.

Anti-Bacterial Agents↗
PubMed1979

Hormonal response to volume depletion in non-nephrectomised patients on regular haemodialysis.

The hormonal response to volume depletion by isolated ultrafiltration has been studied in seven non-nephrectomised haemodialysis patients. The mean reduction in blood volume was 14%, and pulmonary artery wedge pressure reduction averaged 77%. No increments in heart rate were observed in any of the patients. Cardiac output decreased while systemic vascular resistance increased. Mean arterial blood pressure remained stable in all but two patients. Significant increments in plasma vasopressin concentration were only found during hypotensive episodes, while in the whole group no significant increase was found. Both plasma renin activity, plasma aldosterone and plasma cortisol increased significantly during isolated ultrafiltration. The moderate increase in systemic vascular resistance indicates that the peripheral sympathetic nervous system - at least partly - was functioning. It was, however, not correlated with changes in any of the measured hormones. Furthermore the adrenal and cardiac response appeared to be absent.

Aldosterone↗
PubMed1979

Scintigraphic skeletal changes in non-dialyzed patients with advanced renal failure.

Technetium-99m-polyphosphate (Tc-PP) bone scintigraphy was performed in 51 patients with advanced renal failure in order to evaluate the applicability of this method in detection of metabolic bone changes in these patients. The creatinine clearance varied from 2 to 40 ml/min and none of the patients had previously been on dialysis treatment. The scintigrams were graded according to the focal and the generalized abnormal uptake of the tracer in the skeleton. 34 patients showed generalized scintigraphic changes and among these the changes in 18 patients were classified as severe. An inverse correlation was found between the kidney function and the generalized scintigraphic classification. Focal bone changes were found in 11 patients. In order to evaluate the influence of the lack of kidney function on the scintigraphic results, 3 patients with acute oliguric renal failure were examined. All had normal scintigrams. It is concluded that Tc-PP bone scintigraphy is a sensitive method in revealing renal osteodystrophy in non-dialyzed patients with advanced renal failure in agreement with previous reports on patients on chronic hemodialysis and after kidney transplantation.

Adolescent↗
PubMed1978

Radioimmunoassay of 8-arginine-vasopressin (antidiuretic hormone) in human plasma.

A radioimmunoassay for 8-arginine-vasopressin (AVP) measurement in human plasma has been developed and evaluated, using a commercial preparation of an antibody of AVP. Detection limit of the assay was 0.4 pg. A simple acetone extraction procedure gave a recovery of 65% of added [125I]AVP. The overall sensitivity in the assay was 1.0 pg/ml when 2 ml plasma samples were extracted. The antigenic sites of the employed antibody seemed to be a combination of amino acid residues in the tripeptide tail and the pentapeptide ring. This can explain that the antibody was almost completely insensitive to chemically or enzymatically degraded AVP. The inter-assay coefficient of variation for the control plasma pools averaged 17%. A good correlation to plasma osmolalities above 290 has been found. AVP level in recumbent subjects (n = 8) with plasma osmolalities in the normal range was 2.8 +/- 1.0 pg/ml (mean +/- SD) and in ambulatory subjects (n = 10) on ad lib. water intake 4.5 +/- 1.9 pg/ml (mean /+- SD).

Adult↗
PubMed1978

Social networks and schizophrenia.

This article suggests that social network concepts and methods can provide a unifying framework for social research on schizophrenia. A selective review of the literature indicates that a social network perspective is not only consistent with a range of other research approaches and findings, but may help resolve some basic and persistent methodological and conceptual problems. A theoretical model is briefly described which attributes a critical role in the onset and recurrence of schizophrenia to social network processes. Some examples are given of the potential contribution of social network variables to research and therapy in schizophrenia.

Acculturation↗
PubMed1978

Calcium-dependent aldosterone secretion in anephric and nonnephrectomized patients on regular hemodialysis.

The present study was undertaken to investigate the effect of a continuous calcium infusion on the plasma levels of aldosterone, renin activity, and cortisol in six anephric and four nonnephrectomized patients on regular hemodialysis. In both groups, a significant increase in whole blood ionized calcium (b-Ca2+) was demonstrated. A significant increase in plasma aldosterone (PAC) was noted in the nonnephrectomized patients, in whom the rise in PAC correlated with the increase in b-Ca2+. However, in the anephric patients only a smaller and insignificant increase in PAC was found. No significant changes were demonstrated in plasma cortisol or renin activity, nor in potassium or sodium concentrations in either group. It is concluded that ionized calcium influences the plasma levels of aldosterone in uremic patients on regular hemodialysis.

Adrenocorticotropic Hormone↗
PubMed1977

The adrenocortical response to angiotensin II infusion in anephric and non-nephrectomized patients on regular hemodialysis.

In the present study 8 anephric and 4 non-nephrectomized patients were stimulated with angiotensin II (A-II). In 5 of the anephric patients, an increased plasma aldosterone concentration (PAC) in response to ACTH stimulation had previously been demonstrated. After A-II stimulation, all 8 anephric patients responded with a significant rise in PAC although the increase was less pronounced than in 4 non-nephrectomized patients. In both groups of patients the increase in PAC was correlated to the increase in diastolic and systolic BP and to the A-II dose. Furthermore, in the non-nephrectomized patients, the plasma renin activity showed a significant decline, which was inversely correlated to the increase in PAC. When all 12 patients, regardless of the difference in remaining renin-angiotensin system, were considered as one population, the variable basal levels of PAC correlated significantly to the increase in PAC during A-II and ACTH stimulation. It is concluded that the adrenals of anephric man respond to A-II with an increase in PAC and that the reason for a lower response appears to be the lack of the renin-angiotensin system.

Adrenal Cortex↗
PubMed1977

Circadian rhythm of plasma aldosterone and plasma renin activity in steroid and non-steroid treated kidney transplanted patients.

The circadian rhythm of plasma aldosterone (PAC) and cortisol concentration (PCC), and renin activity (PRA) was measured in five steroid and five non-steroid treated kidney transplanted patients--all with denervated kidney grafts--and compared with four normal controls and two steroid-treated patients with non-renal disease and thus normal renal innervation. The non-steroid treated patients had a normal circadian thythm of PAC and PCC, but without variation of PRA, suggesting that denervation of the kidneys has no influence on the circadian rhythm of PAC. In both steroid treated groups the PAC showed an inverse diurnal variation--now correlating to the diurnal variation in PRA. The inverse circadian rhythm of PAC in patients with suppressed ACTH secretion remains unexplained, but is in accordance with the nocturnal peak of sodium and water excretion in steroid treated patients.

Adult↗
PubMed1976

Urinary pseudouridine and beta-aminoisobutyric acid in patients with low grade urothelial tumours. Relations between excretion and tumour recurrence.

The simultaneous 24 hours excretion of pseudouridine and beta-aminoisobutyric acid in the urine from patients treated for low grade urothelial tumours has been determined and related to tumour recurrence inside of 6 months after the determinations. The results of 53 assays in 39 patients without clinical signs of recurrence at the time of the detrmination showed a high excretion of pseudouridine in 53% and of beta-aminoisobutyric acid in 28.5% of the assays. Recurrences appeared more often after a high urinary pseudouridine (53.5%) than after a low, but the difference was not statistically significant (p more than 0.05) and more often after a low urinary beta-aminoisobutyric acid (52.5%) than after a high (p less than 0.01). The highest incidence of recurrence was in patients with a simultaneously high urinary pseudouridine and a low urinary beta-aminoisobutyric acid. Seventy per cent of these excretion patterns were from patients, who developed a recurrence before 6 months (p less than 0.002).

Adult↗
PubMed1975

Relationship between effective intensity of auditory stimulation and directional eye turns in the human newborn.

To examine Schneirla's biphasic hypothesis that effectively weak stimulation results in approach-type responses and effectively strong stimulation results in withdrawal-type responses, 90 dB white noise stimuli were presented to twenty-five, 2-day-old female infants. Based on prior investigation this stimulus was expected to be effectively strong when presented at the right ear and effectively weak when presented at the left ear. Results obtained from electro-oculargraphic recording of the infants' eye movements supported this hypothesis in that significant towards-turning occurred when the stimulus was presented at the left ear and significant away-turning occurred when the stimulus was presented at the right ear.

Acoustic Stimulation↗
PubMed1975

A study on the clinical significance of urinary beta-aminoisobutyric acid in patients with urothelial tumours.

Urinary beta-aminoisobutyric acid (beta-AIB) has been measured in 141 patients with urothelial tumours and 60 controls. Ninetyone of the patients have been followed-up for an average period of about 2 years, which included many determinations of the beta-AIB excretion. Thirtysix patients died during the control periods. Urinary beta-AIB was found to be significantly correlated to the grade of tumour cell dysplasia, but not to the clinical tumour stage. The treatment had no major influence on the excretion. Characteristic changes in the excretion preceding high-grade tumour recurrences are demonstrated. Autopsy findings with tumour tissue in the urinary tract and distant metastases were significantly correlated to a low urinary beta-AIB in the terminal phase of the disease. The results are discussed in relation to the degradation of thymine, the dual origin of beta-AIB and the tumour-host metabolism. It is concluded, that urinary beta-AIB can contribute to the graduation of malignancy, but is not valuable as a general screening procedure for urothelial cancer.

Aged↗
PubMed1974

Gap junction formation between reaggregated Novikoff hepatoma cells.

We have combined freeze-fracture and electrophysiological methods in a study of gap junction formation between reaggregated Novikoff hepatoma cells. Cell clumps are dissociated with EDTA, and the resulting single cells are allowed to reaggregate (5-180 min) in loose pellets in the presence of calcium at 37 degrees . The earliest electron microscopic evidence for the genesis of new junctions is the appearance of flattened regions of the plasma membrane with a relative paucity of small intramembranous particles. These regions contain instead loosely organized groupings of 9- to 11-nm intramembranous particles, which are seen on the A face of the fractured plasma membrane, while corresponding pits occur on the membrane B face. We have termed the specialized membrane regions "formation plaques." They are seen as early as 5 min after reaggregation and are quite numerous by 30 min. Larger plaques are observed at later times. Plaques seen at 30 min are consistently matched with other plaques on apposed cells, although the extracellular space separating these structures still exceeds 10 nm. By 60 min, some matched plaques display a reduced extracellular space, resembling that of normal gap junctions. Between 30 and 60 min, aggregates of closely packed particles on A faces and hexagonally arranged pits on B faces frequently appear in the formation plaques. The aggregates, which are indistinguishable from small gap junctions, appear to enlarge over the subsequent 2-hr period as the number of unaggregated 9- to 11-nm particles declines. Microelectrode studies demonstrate progressive increases in the percent of interfaces containing lowresistance junctions and in the degree of elctrical coupling in preparations incubated up to 2 hr. Coupling is first detected at about the same time as particle aggregates (or formation plaques with reduced extracellular spaces), and increases as aggregate sizes increase.

Carcinoma, Hepatocellular↗