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Biomedical subjects

G Schmid

Publications and source records attributed to G Schmid.

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

BAEE esterase (kallikrein-like) activity in parotid saliva of normal rats and rats with various forms of experimental hypertension (genuine, renovascular and DOCA salt hypertension).

A technique for continuous and quantitative collection of parotid saliva including salivary flow rate determination for in vitro experiments in rats is described. Kallikrein-like activity in parotid saliva of rats with various forms of arterial hypertension (genuine, renovascular and DOCA salt hypertension) was studied. Kallikrein-like excretion was measured by its estoerolytic activity using benzoyl arginine ethyl ester (BAEE) as a substrate. The levels of kallikrein-like activity in parotid saliva of normotensive control rats ranged between 2.5 and 4.0 mU/min during salivary flow stimulation with pilocarpine. In all forms of experimental hypertension kallikrein-like activity in saliva was increased two-to fourfold. This increase was not related to the activity of the renin-angiotensin system.

Animals↗
PubMed1980

[Diurnal variation of the elevated acid phosphatase activity in cases of prostate carcinoma (author's transl)].

The diurnal rhythm of total acid phosphatase and prostatic phosphatase activities was investigated in patients with prostate carcinoma. In these patients, the activities of total acid phosphatase, the tartrate-sensitive fraction of acid phosphatase, and lactate dehydrogenase decrease after therapy, whereas the activity of alkaline phosphatase increases. In all patients with prostate carcinoma, the total and tartrate-inhibited acid phosphatase, and the level of cortisol show a diurnal rhythm before therapy, with a minimum at night. In one patient, after orchiectomy, the cortisol rhythm remained unchanged, but the daily phosphatase variation was absent. Diurnal variations of lactate dehydrogenase and alkaline phosphatase were also observed in 2 patients without prostate carcinoma, but with elevated levels of these enzymes.

Acid Phosphatase↗
PubMed1980

Biochemical variations in electrically induced intimal smooth muscle cell proliferates of the rabbit carotid artery.

Common carotid arteries of rabbits were locally stimulated every day by chronically repeated electrical impulses for periods up to 4 weeks. Morphological observations revealed that, primarily at the anodal site of the stimulated segment, smooth muscle cells penetrated from the media through the internal elastic membrane and proliferated in the subendothelial space below a morphologically unchanged endothelium. When the plasma cholesterol was raised by cholesterol feeding, typical atheromatous plaques were formed. Biochemical studies showed an increased metabolic activity of the proliferating cells; in comparison with normal intima-media, the tissue content of DNA, protein, and lactate was increased, whereas that of glucose and glycogen was decreased in the proliferates. Furthermore, during in vitro incubation, the uptake of oxygen and glucose and the production of lactate was enhanced. The increased energy consumption of the proliferates indicates a modified metabolic function of these cells.

Animals↗
PubMed1979

Salivary kallikrein excretion in hypertension.

According to immunohistochemical investigations kallikrein in the majors salivary glands is located predominantly at the apical border of the striated duct cells and as a luminal rim in the main excretory ducts. Comparatively the highest concentrations are observed in the submandibular gland of rats and cats in the cytoplasmic granules of the granular tubules. In normal humans and rats the kallikrein activity of parotid saliva is inversely related to flow rate and sodium concentration. An increased salivary kallikrein concentration is found in human essential hypertension and renoparenchymal hypertension associated with impaired kidney function. Furthermore in rats with various forms of hypertension (genetic hypertension, DOCTMA salt and renovascular hypertension) the salivary kallikrein secretion - as determined by the BAEE-esterase activity - is enhanced. In contrast to the kallikrein secretion the flow dependent sodium concentration of parotid saliva is reduced in human essential and renoparenchymal hypertension as well as in rats with various forms of experimental and genetic hypertension, which indicates an enhanced sodium reabsorption in the glandular duct system. Furthermore in most forms of hypertension, there is a tendency of higher potassium levels in the saliva. The pathogenesis of the enhanced glandular kallikrein secretion in hypertension is discussed with regard to a counterregulatory mechanism in hypertension as well as to a sympathicoadrenergic activation. The enhanced sodium reabsorption in the duct system in the various forms of hypertension could be the cause as well as a consequence of the enhanced kallikrein secretion.

Absorption↗
PubMed1979

Kallikrein excretion in parotid saliva in rats with various forms of arterial hypertension.

A technique for continuous and quantitative collection of parotid saliva--including salivary flow rate determination--for in vivo experiments in rats is described. Excretion of kallikrein-like activity in parotid saliva of rats with various forms of arterial hypertension (genuine, renovascular and DOCTMA-salt hypertension) was studied. Kallikrein excretion was measured by its esterolytic activity. The levels of kallikrein-like activity in parotid saliva of normotensive control rats ranged between 2.5--4.0 mU/min during salivary flow stimulation with pilocarpine. In all forms of experimental hypertension salivary excretion of kallikrein-like activity was increased 2--4 fold. This increase was not related to the activity of the renin-angiotensin system.

Animals↗
PubMed1979

Dissociation and aggregation of lactic dehydrogenase by high hydrostatic pressure.

As shown by earlier experiments high hydrostatic pressure affects the catalytic function of lactic dehydrogenase from rabbit muscle. In the presence of substrates denaturation occurs, whereas in the absence of substrates and --SH-protecting reagents oxidation of sulfhydryl groups takes place [Schmid, G., Lüdemann, H.-D. & Jaenicke, R. (1975) Biophys. Chem. 3, 90--98; (1978) Eur. J. Biochem. 86, 219--224]. Avoiding oxidation effects by reducing conditions in the solvent medium and by chelation of heavy metal ions, the remaining high-pressure effects consist of dissociation of the native quaternary structure into subunits followed by aggregation. Both reactions are influenced by temperature and enzyme concentration. Short incubation (less than or equal to 10 min) at pH 6.0--8.5 and pressures of 0.3--1.0 kbar causes dissociation which is reversed at normal pressure. At 5 degrees C the activation volume is found to be delta V not equal to = -62 +/- 3cm3 . mol-1. Above 1.2 kbar irreversible aggregation takes place; the reaction is favoured by low temperature and decreased pH. The activation volume for the aggregation process at 5 degress C is delta V not equal to = -97 +/- 3cm3 . mol-1. The results may be described by a reaction sequence comprisign pressure-induced dissociation of the native enzyme into its subunits followed by subunit aggregation to form inactive high-molecular-weight particles.

Animals↗
PubMed1979

The flow volume curve: normal standards in young subjects.

During epidemiological survey, satisfactory flow-volume data were obtained from 438 young Italian Boy-Scouts. Data from 302 non-smoking subjects (170 males and 132 females, ranging in age from 10 to 20 years) free of symptoms or history of cardiorespiratory disease were used in determining "normal" prediction equations and nomograms for peak expiratory flow (PEF), maximal expiratory flow at 75 percent (V 75%), 50 percent (V 50%), 25 percent (V 25%) of the forced vital capacity. The flow-volume curve showed for the same height and age evident intersubject variability. The prediction equations and nomograms give mean values but no information on scatter.

Adolescent↗
PubMed1978

A simplified method for measurement of Ca++-activity in serum, using serum-monovettes and a Ca++-selective disk-electrode.

A simplified method for the anaerobic measurement of ionized calcium in serum of venous blood by use of ion-selective electrodes--the monovette-technique--is described. For estimation of Ca++ a new electrode type--the disk-electrode (11, 12, 13, 14)--charged with a synthetic, electrically neutral Ca++-carrier of the octandioic acid-type (1), is tested.

Blood Chemical Analysis↗
PubMed1978

Technique of continuous collection of parotid saliva in the rat.

A method is described, which is suitable to collect continuously and quantitatively saliva from both parotid glands in rats under in vivo conditions and which allows to investigate salivary electrolyte composition in relation to flow rate during several hours. This might be of expanding scientific interest in disturbances of transepithelial electrolyte transport in various pathophysiological situations (for instance different forms of experimental hypertension, endstage renal failure and so on).

Animals↗
PubMed1978

Calcium metabolism and enzyme secretion in guinea pig pancreas. Uptake, storage and release of calcium in whole cells and mitochondrial and microsomal fractions.

In isolated pancreatic acinar cells from the guinea pig stimulation of enzyme secretion by carbamoylcholine is slightly diminished in the absence of extracellular Ca. LaCl3 in a concentration, which does not influence the secretory response to carbamoylcholine, nearly completely abolishes 45Ca uptake by cells, indicating that Ca uptake is not necessary for secretion. In cells preloaded with 45CaCl2, addition of carbamoylcholine leads to an immediate release of 45Ca, which can be blocked by atropine or 8-(N,N-diethylamino)-octyl 3,4,5-trimethoxybenzoate and is not influences by LaCl3 in concentrations, which do not inhibit secretion. A similar release of 45CaCl2 from preloaded cells is obtained by addition of the mitochondrial inhibitors antimycin A, carbonylcyanide p trifluoromethoxyphenylhydrazone (FCCP), and oligomycin. Possibly due to markedly diminished ATP levels, neither antimycin A nor FCCP act as secretagogues, both compounds being inhibitors of secretion. Oligomycin, which decreases ATP levels only to 20%, stimulates secretion. Mitochondria and microsomes from pancreatic tissue are able to accumulate 45Ca. Mitochondrial 45Ca uptake can be driven by ATP or active respiration and is inhibited by NaN3, oligomycin, antimycin A or FCCP. Microsomal 45Ca uptake is ATP-dependent. NaN3 and mitochondrial inhibitors have no influence on microsomal 45Ca uptake, which is stimulated several-fold by oxalate. The results support the assumption, that in the guinea pig pancreas Ca mobilization from intracellular stores is necessary to initiate secretion. Due to their ability for an active accumulation of45Ca both mitochondria and microsomes could serve as intracellular calcium stores.

Amylases↗
PubMed1978

Decreased cAMP content of the hypothalamus of genetically hypertensive rats.

In genetically hypertensive rats an altered catecholamine content of hypothalamic structures has been reported. In the present study cAMP was estimated in the hypothalamus and cortex of genetically hypertensive rats and compared with normotensive controls of the same strain. It is shown, that the cAMP content of the hypothalamus of the hypertensive animals was decreased to about 60% of control values, whereas there was no difference of the cAMP content in the cortical regions of the same animals. These results indicate an alteration of the adenyl cyclase-cAMP-phosphodiesterase system in hypothalamic structures of genetically hypertensive rats.

Animals↗
PubMed1978

Increased histidine and histamine content in the brain of chronic uremic rats. Cause of enhanced cerebral cyclic adenosine monophosphate in uremia?

In rats with experimental chronic renal insufficiency (90% nephrectomy) the histidine content in brain was increased (+ 35%) in spite of normal plasma values and decreased concentrations in the striated muscle (-23%). The finding of a raised histidine level in the brain seems to be a uremia specific disorder, probably cuased by a local disturbance in histidine metabolism. In addition an increase of the histidine decarboxylation product histamine could be observed in the brain of rats with chronic renal insufficiency, as compared to pair-fed controls. This increase was directly related to the severity of azotemia. In the pathogenesis of the histamine alteration the increased histidine content in the brain of uremic rats must be considered, since the specific histidine decarboxylase is not saturated by the normal endogenous level of the amino acid precursor. Probably the increased histamine contributes to the raised cerebral cyclic AMP in the brain of uremic rats.

Animals↗
PubMed1978

Oxidation of sulfhydryl groups in lactate dehydrogenase under high hydrostatic pressure.

Lactate dehydrogenase from rabbit skeletal muscle in the presence of substrate exhibits irreversible deactivation at hydrostatic pressures beyond 1 kbar [Schmid, G., Lüdemann, H.-D. & Jaenicke, R. (1975) Biophys. Chem. 3, 90-98]. In the absence of substrate and coenzyme the lability towards pressure is enhanced. The pH dependence of the effect and its inhibition by SH-protecting agents suggest the oxidation of sulfhydryl groups to be involved in the mechanism of deactivation. Partial deactivation observed at pH 5.5-7.0 becomes complete in the range of the intrinsic pK of cysteine; addition of dithiothreitol and/or EDTA protects the enzyme from complete deactivation, and leads to the residual enzymatic activity observed at pH 7.0. Incubation of the enzyme with dithiothreitol after pressure deactivation at pH 8.5 causes partial reactivation. From pressure-dependent measurements of the kinetics of deactivation an activation volume of deltaVnot equal to = -285 +/- 30 cm3 . mol-1 is calculated, which exceeds numerical data reported for typical reactions in organic chemistry. Therefore, the assumption can be made that the oxidation of sulfhydryl groups is connected with structural changes in the enzyme in the rate-determining step of the deactivation. The proposed mechanism may contribute to the toxicity of oxygen towards bacteria under high hydrostatic pressure.

Animals↗
PubMed1977

[Late-onset cutis laxa (generalized elastolysis)].

Cutis laxa is a heterogeneous disease of elastic fibres, divided into three congenital and two acquired forms. Its aetiology is unknown except for the X-linked recessive form. A late form with slow progression in a 52-year-old woman and a probably postinflammatory form in a 29-year-old woman are reported. In both cases histological examination revealed severe damage of the elastic fibres of the skin, in the first one also calcium deposits and (electronmicroscopically) damage to collagen fibres. Treatment is entirely symptomatic, but in severe cases plastic surgery may help cosmetically.

Adult↗
PubMed1977

Intracellular histidine content of various tissues (brain, striated muscle and liver) in experimental chronic renal failure.

Intracellular histidine levels were determined in brain, striated muscle and liver of rats with chronic renal insufficiency (5/6-nephrectomy) and compared both with normal rats and food-restricted (pair-fed) animals. There was no difference in plasma histidine concentration of the three groups whereas in the brain of the uremic rats histidine was significantly increased. Since there existed no alteration of the cerebral histidine in the corresponding pair-fed group, the finding of a raised histidine level in the renal insufficient rats seems to be due to a specific uremic disorder caused by a cerebral disturbance in histidine metabolism.

Animals↗