[Lentivirus infections in goats with carpitis and interstitial mastitis].
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Animals↗
Biomedical subjects
M Weiss
Publications and source records attributed to M Weiss.
Evoked potential studies of the effects of impact acceleration on the motor nervous system.
The initial results of a continuing investigation into the effects of various levels of impact acceleration on the functional integrity of the motor nervous system are summarized. The results are based on the measurement of alterations in neural transmission along the motor pathway of the Rhesus monkey as revealed by latency and amplitude changes in the motor pathway evoked potential (EP) following the delivery of various levels of impact acceleration to a test vehicle. The EPs were produced by electrical stimulation of and recording from the motor pathway of experimental animals subjected to -Y (lateral impact) acceleration and animals subjected to -X (frontal impact) acceleration. High resolution latency and amplitude measures of the EP recorded from these animals before and after impact were tracked so that the time course of recovery of nerve propagation following impact could be accurately assessed. Analysis of these EP measures revealed that the time course of recovery to preimpact values is directly related to the intensity of the acceleration impulse delivered to the test vehicle.
Acceleration↗
Tomoscintigraphic assessment of myocardial metabolic heterogenity.
I-123-omega-heptadecanoic acid (HDA) was evaluated for myocardial scanning in 59 healthy volunteers and 133 patients, using a 7-pinhole collimator. Early (uptake) and late (retention) images were compared visually. Regional HDA elimination was also followed semiquantitatively based on the calculation of a retention-over-uptake ratio, R(phi), derived from the maximal counts/pixel in 60 midventricular slice sectors. The healthy heart concentrated HDA homogeneously in all segments with no difference between early and late images. The minimal R(phi), taken as representative of that myocardium with the best function, was unchanged after maximal ergometer stress and with dipyramidole-induced hyperperfusion. A circumscribed decreased HDA uptake is the clear-cut criterion for an abnormal finding. HDA tomography of the myocardium had an 86% sensitivity for myocardial infarcts (MIs) up to 4 wk old, and 83% for myocardial scars (MSs). Comparing early and late tomograms, we find a cool-warm sequence more often with acute and subacute MIs. A cool-cool or a cold-cold sequence dominated with MSs. HDA tomoscintigraphy cannot replace TI-201 for the evaluation of regional coronary reserve in coronary heart disease.
Adult↗
Stability of phenylpropanolamine hydrochloride in liquid formulations containing sugars.
Stability studies with a decongestant syrup formulation containing phenylpropanolamine hydrochloride in a sugar vehicle indicated a loss of phenylpropanolamine hydrochloride. To ascertain the biological significance of this indicated chemical loss, the degraded formulation was administered to human volunteers and the urinary excretion of phenylpropanolamine hydrochloride was determined. The excretion and chemical assay patterns were in good agreement, indicating that the sugar vehicle was both chemically and biologically incompatible with phenlypropanolamine hydrochloride. A control formulation made with phenylpropanolamine hydrochloride in a sorbitol vehicle showed good chemical stability and urinary excretion patterns. Further studies showed chemical losses with phenylpropanolamine hydrochloride in the presence of fructose, dextrose, and 5-(hydroxymethyl)-2-furaldehyde but not with levulinic acid. Possible mechanisms for the sugar-phenylpropanolamine hydrochloride interaction are discussed.
Carbohydrates↗
Raphe - cerebellum interactions. I. Effects of cerebellar stimulation and harmaline administration on single unit activity of midbrain raphe neurons in the rat.
The firing patterns of single raphe units at the posterior midbrain level were examined in chloralosed rats to assess the effects of cerebellar stimulation and/or harmaline administration. Raphe cells were grouped according to their spontaneous firing rate and other characteristics into two categories. From a total sample of 160 cells, 106 (66%) presenting a slow regular discharge pattern were classified as serotonergic (5-HT cells), whereas 35 (22%), having a faster firing rate, were considered non serotonergic (NS cells). Moreover, 19 (12%) raphe units were non categorized. Cerebellar juxtafastigial (JF) stimulation modified the discharge pattern of 56 (35%) raphe units. The remaining 65% were unaffected by the stimulation. Of the 41 5-HT cells affected by JF stimulation, 28 neurons (68%) showed a systematic increase of their firing rate, whereas of the 12 NS cells affected 8 neurons (66%) were inhibited. It thus appears that cerebellar stimulation has an opposite effect on raphe units according to the cell types. Harmaline administration suppressed the activity of 5-HT cells and increased the discharge rate of NS cells. Moreover, we noticed in the latter units a phase modulation of the firing pattern by pauses occurring with a fixed periodicity of 2.5 to 10 s. Considered in the context of previous studies, these results strongly suggest an inhibitory influence of the raphe system on the olivo-cerebellar circuitry.
Alkaloids↗
Raphe - cerebellum interactions. II. Effects of midbrain raphe stimulation and harmaline administration on single unit activity of cerebellar cortical cells in the rat.
The effects of midbrain raphe stimulation and/or harmaline administration on cerebellar cell activities were examined in chloralosed rats. Cerebellar cortical cells were grouped into two categories. From a total sample of 68 cells, 48 were classified as Purkinje cells and the 20 others were unidentified. Midbrain raphe stimulation was found to inhibit for many sec the discharge of 40% of the Purkinje cells and 80% of the unidentified units. Other cells were unaffected, except 4 of them which were excited. Harmaline administration increased the CS firing rate of all Purkinje cells by inducing a rhythmic CS discharge at 7-12 Hz. Moreover, harmaline increased the discharge rate of unidentified units without inducing rhythmic activity. In both types of cerebellar cells a modulation of their firing pattern by periodical pauses at 0.1-0.4/s was noticed. These data are discussed in relation to the known influences of harmaline and cerebellar stimulation on raphe neurons. Taken in this context, results presented here confirm the existence of a modulatory influence of the raphe nuclei on the olivo-cerebellar circuitry. A general model of interactions is proposed.
Alkaloids↗
Moments of physiological transit time distributions and the time course of drug disposition in the body.
Characterizing the tissue distribution kinetics of drugs by physiological and physico-chemical parameters and using a circulatory model the time course of blood concentration after intravenous injection is predicted for linear pharmacokinetic systems. The interrelationships between the first three (zero to second) moments of the distribution functions of organ transfer times, circulation times and residence times of drug molecules in the body are described. Utilizing literature data the model is applied to the analysis of lidocain kinetics in humans.
Humans↗
The possible mechanisms of the high pressure-induced motor disturbances in the cat.
High pressures elicit a high-frequency tremor (8-12 c/sec) in mammals, the mechanisms of which are still unknown. The present study shows that: (1) in spite of many similarities observed between the EMG characteristics of harmaline-induced tremor and pressure-induced tremor, cerebellar lesions which suppress the harmaline-induced tremor, do not modify the characteristics of the pressure-induced tremor; (2) at depth, the caudal part of the spinal cat (section at T9-T10 spinal level) displays irregular spontaneous EMG activities which can be clonic or rhythmic (4-8 c/sec), and a neuromuscular stretch hyperreflexivity. These data suggest that the origin of the pressure-induced tremor is spinal and neuromuscular rather than cerebellar.
Animals↗
Sex differences in steroidogenesis by adrenal homogenates of adult possum (Trichosurus vulpecula) attributable to the steroids formed by the adrenocortical special zone of the female.
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Adrenal Cortex↗
myo-inositol in the reproductive tract of the female rat.
1. myo-Inositol concentrations in oviduct, ovary and uterus were many-fold those of blood serum during all four stages of the estrous cycle of the female rat. 2. Inositol concentration was higher in oviduct than in ovary or uterus and was lower in uterine fluid than in uterus. 3. Estrus uteri had higher inositol concentrations than uteri in other phases of the cycle. 4. In order to measure dynamic aspects of the distribution of inositol, the distribution of radioactivity among organs of the reproductive tract of mature female rats was measured 45 min after i.p. injection of [2-3H]myo-inositol. 5. These organs concentrated inositol from the blood, and the tissue radioactivity (expressed as dpm/mg wet wt of tissue) increased in the sequence: vagina less than cervix less than uterus less than ovary less than oviduct. 6. The uterus and ovary concentrated myo-inositol more strongly during proestrus than during metestrus, diestrus of estrus. 7. The contents of proestrus follicles were more highly radioactive than was the ovary itself, whereas proestrus uterine fluid was less radioactive than the uterine tissue.
Animals↗
Rhythmic activity of spinal interneurons in harmaline-treated cats. A model for olivo-cerebellar influence at the spinal level.
After harmaline administration, rhythmic discharges at 8-12 c/s were obtained by intracellular recording from interneurons in the lumbo-sacral cord of decerebrate paralyzed cats. Unitary extracellular recordings were also made from cerebellar Purkinje cells, showing a rhythmic complex spike activity. Simultaneous recordings of cerebellar and spinal interneurons reveal a precise time relation between rhythmic activities recorded at these two levels. Following each rhythmic cerebellar signal one can note an interruption of interneuron activity. It is also noted that sustained high frequency tonic firing of interneurons coincides with cessation of cerebellar rhythmic activity. These facts are related to the impingement of a disfacilitatory supraspinal influence on spinal interneurons. A model of the mechanisms of signal transfer along the olivo-cerebello-bulbo-spinal system is proposed, according to which tremorogenic supraspinal influences might act on motoneurons by disfacilitating excitatory or inhibitory interneurons.
Action Potentials↗
The use of human gamma globulin in renal transplantation.
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Graft Survival↗
Effects of a dietary prostaglandin precursor on the progression of experimentally induced chronic renal failure.
The effect of increasing a dietary PG precursor on the progression of chronic renal failure was studied in the partially nephrectomized rat. NLA or HLA diets were pair-fed to groups of 3/4-nephrectomized and sham-operated rats. Serum creatinine and urinary protein excretion were measured serially. Nephrectomized rats on the NLA diet had progressive deterioration of renal function, the serum creatinine level rising to 1.55 mg/dl by week 20. At week 20, by contrast, nephrectomized rats on the HLA diet maintained stable renal function; the serum creatinine level was 0.97 mg/dl at week 20. Urinary protein excretion was significantly lower and glomerular sclerosis was prevented in the rats fed the HLA diet. No changes were observed in the levels of blood pressure, serum cholesterol, or serum triglycerides as an effect of the diet. Increased PGE2 production, measured by radioimmunoassay in the renal cortex of rats on the HLA diet, suggested that the protective effect upon renal function in this model of chronic renal failure may be mediated by increased renal cortical PG formation.
Animals↗
Dialysis treatment of acute chromium intoxication and comparative efficacy of peritoneal versus hemodialysis in chromium removal.
External burns with chromic acid have been fatal even in cases with corrosions covering less than 10% of the body surface area. We observed a 19-year-old man with third-degree burns and chromium intoxication following accidental contact of both legs with chromium acid solution. The initial course was characterized by serum chromium levels known to be usually lethal (220 micrograms/100 ml), complete anuria, hepatic damage and progressive anemia. Aggressive peritoneal dialysis with a total duration of 252 h between the 4th and 22nd day after exposure caused a progressive decrease in serum chromium levels and resulted in a complete recovery after 35 days. The comparative efficacy of peritoneal versus hemodialysis in chromium removal was evaluated in 5 patients with acute renal failure who were treated with peritoneal dialysis and in 6 patients with end-stage renal failure who underwent hemodialysis. Following intravenous injection of 500 muCi51CrCl3 chromium clearance averaged 0.8 +/- 0.3 ml/min and 2.5 +/- 0.8 ml/min during peritoneal dialysis (n = 50) or hemodialysis (n = 24), respectively. It is concluded that hemodialysis is about 3 times as effective as peritoneal dialysis in chromium removal per unit of time. However, the possibility of applying uninterrupted peritoneal dialysis during the first few days suggests that this method is at least equivalent to hemodialysis for treatment in the initial stage of chromium intoxication.
Acute Disease↗
[Biological availability of digoxin and beta-methyl-digoxin administered in the fasting state or after meals].
Ten healthy volunteers were given 0.75 mg digoxin and 0.5 mg beta-methyl-digoxin (BMD) in tablet form in the fasting state or after breakfast. Serum concentrations and 24-hour urine excretion of glycoside were measured by radioimmunoassay. Neither the mean area under the serum concentration curve nor the mean cumulative urinary excretion was significantly changed by postprandial administration. Peak serum concentrations were higher when the subjects took the tablets while fasting than when they took them postprandially, but the difference was significant only for BMD. After BMD in the fed state the peak serum concentration was reached earlier and with less variation than after digoxin, but -- as after administration in the fasting state -- the differences were not significant. The peak serum concentration and the time when it is achieved are, as parameters for the rate of absorption, only of secondary importance for treatment with cardiac glycosides in medical practice. They suggest faster absorption of BMD compared with digoxin. Both the glycosides can be given equally well before, during or after food, a fact which facilitates prescription.
Adult↗
Modulation of harmaline-induced rhythmic discharge of the inferior olive by juxtafastigial stimulation.
We previously reported induction or suppression by juxtafastigial stimulation of the rhythmic complex spike discharge of Purkinje cells in harmaline treated rats. In this paper we show that this modulation of the cerebellar rhythmic activity implies the involvement of inferior olive neurons. These results are discussed in the general framework of the olivo-cerebello-bulbar circuitry. A modulatory control of the inferior olive neuron activity by the raphe system is suggested to explain part of these results.
Alkaloids↗
[How strongly does heavy work in the heat affect metabolism?].
The study covered 39 acclimatised workers of a ball-bearing forge, aged 39,03 +/- 9,95 years. Temperature of the air, relative humidity and air speed were measured immediately at work. Additionally electrocardiogram, heart rate and temperature of the skin were continuously transmitted by telemetry. Before and at the end of the shift analysis of blood pressure, heart rate, electrocardiogram, blood cells and coagulation, serum acidity and a great number of other metabolic parameters was performed. The netto calories were calculated as 3250 kcal/8 hours (= 13585 kJ/8 hours). Hematological analysis demonstrated a tendency to increase of leucocytes favouring neutrophil granulocytes. The main alterations comprised decrease of actual pH, base excess and standard bicarbonate. Furthermore serum lactate and triglycerides increased, creatinine attained the upper limit of the normal range, mineralogram remained unchanged by drinking ad libitum. The so called "liver enzymes" remained stable. As to circulatory parameters systolic blood pressure slightly declined whilst heart rate increased.
Acid-Base Equilibrium↗
Longitudinal evaluation of patients with untreated prolactin-secreting pituitary adenomas.
A group of 43 patients with galactorrhea, hyperprolactinemia, and radiographic evidence of pituitary adenomas were followed from 3 to 20 years. Initial polytomography and computerized tomographic (CT) scans revealed no evidence of extrasellar extension. Serum levels of prolactin (PRL) were measured at 6 month intervals, and visual fields were assessed annually. Polytomograms and CT scans were repeated every 9 to 36 months. During the period of follow-up, CT scans (but not polytomograms) indicated tumor enlargement in two patients, both of whom underwent selective transsphenoidal removal of the tumor. Polytomograms and CT scans did not show any change in the other 41 patients, and three of them have resumed normal menses, are no longer lactating, and have normal PRL levels. The initial results of this ongoing study indicate that most patients with small pituitary adenomas can be followed with annual CT scans with or without medical therapy, and that surgical treatment should be reserved for those patients with large tumors, those with visual-field loss, and those who show signs of enlargement of the tumor.
Adenoma↗