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Biomedical subjects

H Schmitt

Publications and source records attributed to H Schmitt.

At least 19 recordsLinked to original sources
PubMed1992

Cardiovascular effects of microinjections of quipazine into nuclei of the medulla oblongata in anaesthetized cats: comparison with L-glutamate.

Unilateral microinjections of quipazine (0.9 micrograms in 50 nl) into the subretrofacial nucleus produced hypertension and a slight tachycardia associated with an increase in renal sympathetic nerve activity. Microinjections of quipazine lateral, caudal or rostral to this nucleus failed to alter blood pressure and heart rate. Similarly, microinjections of l-glutamate (3 nmol in 15 nl) into the subretrofacial nucleus elicited hypertension, tachycardia and renal sympatho-excitation. The magnitude of the pressor response to quipazine was smaller than the response elicited by l-glutamate but its duration was longer. Microinjections of quipazine into the lateral tegmental field at l-glutamate hypertensive sites failed to alter arterial blood pressure and heart rate. In contrast, microinjections of quipazine into the caudal ventrolateral medulla or into the nucleus tractus solitarii produced hypotension and sympatho-inhibition. These effects were prevented by microinjections of the 5-HT2 receptor antagonists, LY 53857 or BW 501C. The present results indicate that stimulation of 5-HT2 receptors of the subretrofacial nucleus produces hypertension and sympatho-excitation whereas stimulation of 5-HT2 receptors in the caudal ventrolateral medulla and in the nucleus tractus solitarii produces hypotension and sympatho-inhibition.

Anesthesia↗
PubMed1992

No evidence for neoantigens in human plasma after photochemical virus inactivation.

Photodynamic virus inactivation of human fresh plasma mediated by visible light in the presence of the phenothiazine dyes methylene blue or toluidine blue was investigated to determine whether it influences functional, structural, and immunological properties of plasma proteins. The activities of the coagulation factors I, VIII, IX, X, and XI were affected to a certain degree, while those of most other plasma proteins were not. The elution profiles obtained by ion exchange chromatography of untreated and photodynamically treated plasma were almost identical. Using a number of antisera against human plasma and single plasma proteins, different immunochemical techniques revealed identical patterns for untreated and treated plasma. Thus, there was no indication that the photodynamic virus inactivation procedure applied considerably influences the properties of plasma proteins.

Antigens↗
PubMed1992

The long-term prognosis of the primary glomerulonephritides. A morphological and clinical analysis of 1747 cases.

Long-term studies of all types of primary glomerulonephritis (GN) taking into consideration the major morphological and clinical findings revealed the following: 1) Endocapillary GN, post-streptococcal type has a very good prognosis when only glomerulitis is present. The prognosis is significantly worse if either interstitial inflammation with fibrosis or nephrotic syndrome (NS) is present at the time of the biopsy. 2) The prognosis of the various types of mesangioproliferative GN (IgA nephritis, non-IgA nephritis, and immunohistologically negative GN) is very good if there is only glomerulitis. The prognosis is worse for all three types when the renal cortical interstitium exhibits inflammation with fibrosis at the time of the biopsy, and is worst of all when both interstitial fibrosis (IF) and the signs of acute renal failure (ARF) are present. Of this group, the type in which there are negative immunohistological findings exhibits the best prognosis. No difference in prognosis is found between IgA nephritis and non-IgA nephritis. 3) Minimal changes GN with NS has a very good prognosis when the interstitium is not involved. The presence of interstitial inflammation and fibrosis worsens the prognosis significantly. 4) Focal sclerosing GN has a much poorer prognosis than minimal changes GN with NS, even when there is glomerulitis only (5- and 10-year renal survival rates (RSRs) of 90% and 67%, respectively). If interstitial inflammation and fibrosis are present, the prognosis is significantly worse (5- and 10-year RSRs of 84% and 55%, respectively). The prognosis is worst when both ARF and IF are present at the time of the biopsy (5- and 10-year RSRs of 56% and 46%, respectively). From the clinical side, the prognosis is significantly worse if, at the time of the biopsy, NS is present or the serum creatinine concentration is elevated to more than 1.3 mg%. 5) Chronic membranous GN has a better prognosis than focal sclerosing GN if glomerulitis only is present (5-year RSR, 88%; 10-year RSR, 77%). If the renal cortical interstitium is also involved (in the form of IF), the prognosis is significantly worse (5-year RSR, 65%; 10-year RSR, 38%). The prognosis in this disease, too, is worst when both ARF and IF are present at the time of the biopsy (5-year RSR, 38%; 10-year RSR, 25%). 6) Membranoproliferative GN has a worse prognosis than any of the types of GN so far mentioned (5-year RSR, 51%; 10-year RSR, 32%).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1992

[Aneurysma spurium following arterial catheterization: diagnosis and follow-up].

Pseudoaneurysm (PA) formation is one possible complication after intra-arterial catheterisation. Due to danger of rupture PA must be clearly differentiated from haematoma. PA is an arterially perfused cavity near the puncture site with direct communication with the femoral artery. Its clinical diagnosis is unreliable. We systematically reviewed 628 patients who had undergone femoral catheterisation (for angiography, PTA, local thrombolysis or aspiration) over a period of 1 year. Duplex scanning was performed within 1 to 3 days after puncture in the cases with the slightest suspicion of PA. In 7 patients (1.1%) PA could be confirmed (2 after angiography, 3 after PTA and 2 after local lysis). On the ultrasound B-mode image PA appears as a low or anechoic structure which can be precisely measured. With pulsed (colour) Doppler, flow can be detected within a PA, allowing easy differentiation from thrombosed PA or from haematoma. The velocity of the systolic inflow-jet as well as of the diastolic outflow can be determined. The velocity of the inflow-jet will usually be much higher than the blood flow velocity in the femoral artery. Duplex-scanning allows repeated non-invasive follow-up examinations for better determination of indications for surgery. Of the 7 diagnosed PA, 2 needed prompt operation (1 because of rupture, 1 because of intense local pain). One patient required operation during follow-up because of increase in size of PA. In the remaining 4 patients, spontaneous thrombosis was observed with repeated duplex examinations.

Aged↗
PubMed1992

Pharmacological analysis of the cardiac effects of 5-HT and some 5-HT receptor agonists in the pithed rat.

A pharmacological analysis of the effects of 5-HT on heart rate has been performed in the pithed rat. 5-HT induced a dose-dependent increase in heart rate whereas 5-HT1 receptor agonists--8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), 5-methoxy-N,N-dimethyl-tryptamine (5-MeODMT), 5-methoxy 3-(1,2,3,6-tetrahydro-4-piridinyl) 1H indole (RU 24969) and 1-(m-trifluoromethylphenyl)-piperazine (TFMPP)--failed to increase heart rate. The increase in heart rate induced by the selective 5-HT2 receptor agonist 1-(2,5-dimethoxy-4-iodo-phenyl)-2-aminopropane (DOI) was not significant. The dose-response curve to 5-HT for its tachycardic effects was shifted two-fold to the right by ketanserin and LY 53857 and nine-fold to the right by methiothepin. The effects of high doses of 5-HT (higher than 100 micrograms/kg iv) were antagonized by methiothepin, (-)propranolol, 2-(2-[4(O-methoxyphenyl)-piperazine-1-yl]-ethyl)4,4-dimethyl-1,3 (2H-4H) isoquinoline-dione (AR-C 239) and by pretreatment with reserpine. The 5-HT1 receptor antagonists, pindolol and spiroxatrine, the 5-HT3 receptor antagonist MDL 72222 and the alpha 2-adrenoceptor blocking agent idazoxan failed to antagonize the tachycardia induced by 5-HT. It is concluded that in the pithed rat, the tachycardia induced by 5-HT remained unexplained (implication of 5-HT2 receptors probably different from the classical vascular 5-HT2 receptor, or implication of 5-HT1C receptors?). Moreover, at high doses (higher than 100 micrograms/kg iv), 5-HT may increase heart rate by releasing catecholamines.

Animals↗
PubMed1992

[Sex and age specific GPT limit values in blood donors].

Excluding blood donations with elevated serum ALT from transfusion is only justified under the assumption that these more frequently transmit unrecognized hepatitis infections. The distribution of such infections in the donor population (with respect to age and sex) should be similar to that of hepatitis B and C, respectively. The prevalence of the latter two infections among our blood donors is the same in both sexes. The exclusion rate, however, is 3-4 times higher for men if equal ALT limits are applied. We therefore determined which ALT limits would give equal exclusion rates for donations of male and female blood donors in order to balance the risk of unrecognized hepatitis in blood donations from the two sex groups. In a second step, we also took each donor's age group into account and determined individual ALT limits for different age and sex groups.

Adolescent↗
PubMed1991

Calcium carbonate as a phosphate binder in dialysis patients: evaluation of an enteric-coated preparation and effect of additional aluminium hydroxide on hyperaluminaemia.

Calcium carbonate has been successfully used as a phosphate binder in patients with chronic renal failure; however, a high frequency of hypercalcaemia has been reported. To study the effects of calcium carbonate preparations with different dissolution characteristics on the incidence of this side effect, we conducted a double-blind, crossover trial in 21 patients undergoing chronic haemodialysis. Aluminum hydroxide therapy was replaced with calcium carbonate. The subjects then randomly received either an enteric-coated or a gastric-coated preparation. Calcium carbonate (3.1-3.6 g/d) controlled serum phosphate concentrations as effectively as aluminium hydroxide (2.9 g/d). Concurrently, there was a significant rise in mean serum calcium and a fall in serum concentrations of both parathyroid hormone and osteocalcin, the latter suggesting a decrease in bone turnover. Overall, hypercalcaemic episodes developed in 9 patients (43%) and occurred at a considerable frequency (33 episodes per 100 patient-months) during treatment with the gastric-coated formulation. Following conversion to enteric-coated calcium carbonate (3.6 g/d) patients had fewer occurrences of hypercalcaemia (12 episodes per 100 patient-months, P less than 0.05) and, as compared to the gastric-coated preparation, increases in serum calcium greater than 3.00 mmol/l were not observed at all. Hyperaluminaemia was regressive during therapy with calcium carbonate, but addition of small doses of aluminium hydroxide caused a large rise in serum aluminium concentrations after infusion of desferrioxamine, indicating an enhanced rate of absorption or aberrant compartmentalization of aluminium. We conclude that calcium carbonate can control hyperphosphataemia in dialysis patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1991

Quipazine-induced hypertension in anaesthetized cats is mediated by central and peripheral 5-HT2 receptors: role of the ventrolateral pressor area.

Quipazine (0.5 mg/kg i.v.) produced a sustained pressor response and an increase in splanchnic nerve activity in intact as well as in baroreceptor-denervated cats without causing a significant change in heart rate. These effects were prevented by the 5-HT2 receptor antagonists, ritanserin (0.5 mg/kg i.v.) or BW 501 C (0.5 mg/kg i.v.). Quipazine induced an hypertensive response and an increase in splanchnic discharge in cats pretreated with prazosin (0.1 mg/kg) or hexamethonium (10 mg/kg i.v.). Bilateral application of quipazine (25 micrograms/side) to the ventrolateral pressor area produced a rapid increase in mean blood pressure and in splanchnic discharge. Pretreatment with prazosin (0.1 mg/kg i.v.) abolished the hypertension but not the sympatho-excitatory effects of quipazine. Local application of the 5-HT2 receptor antagonists, LY53857 (10 micrograms/side) or cyproheptadine (10 micrograms/side), had no effects on blood pressure and splanchnic nerve activity but prevented or reversed the actions of locally applied quipazine. LY 53857 (10 micrograms/side) antagonized the sympatho-excitatory effects of systemically administered quipazine. These results indicate that the cardiovascular changes induced by quipazine in anaesthetized cats are mediated by central 5-HT2 receptors located in the ventrolateral pressor area and by peripheral vascular 5-HT2 receptors.

Animals↗
PubMed1991

Prevalence of antibodies to recombinant hepatitis C virus protein C100-3 and of elevated transaminase levels in blood donors from Northern Germany.

Antibody to recombinant hepatitis C virus protein C100-3 (anti-C100-3) was assayed by a first generation enzyme-linked immunosorbent assay (ELISA; Ortho Diagnostics) in 116,700 blood donors who had not been tested before. Total prevalence of repeatably positive donors was 0.72% (n = 842). Prevalence increased significantly from 0.42% at 18-27 years of age to 1.26% at greater than or equal to 58 years. Donors with elevated serum transaminase levels were significantly more often anti-C100-3 positive, but in 98.7% of donors with current or 99.1% with previous transaminase elevations, anti-C100-3 was not found. Elevated transaminases were more often associated with positive anti-C100-3 in females than in males. However, in the total donor population no significant differences of anti-C100-3 prevalence were found between the sexes. During follow up at three subsequent blood donations, 1.08% of donors were positive at least once, but only 0.48% were consistently positive. The cutoff of the Ortho ELISA was not in the minimum of the frequency distribution between positive and negative samples, but far within the range of the negative signals, i.e. the test is likely to produce a significant number of false-positive results. In retesting positive samples with two ELISAs from other producers only a 22% to 65% agreement was found. In a low prevalence group such as German blood donors, the first generation ELISAs for anti-C100-3 produced more false than specific positive results. Most donors with elevated alanine aminotransferase (ALT) are anti-C100-3 negative.

Adolescent↗
PubMed1991

Photoinactivation of viruses in human fresh plasma by phenothiazine dyes in combination with visible light.

We developed a photodynamic method to inactivate viruses in human fresh plasma. Single plasma bags were illuminated with visible light in the presence of low doses of phenothiazine dyes like methylene blue or toluidine blue. By this treatment the infectivity of different enveloped viruses including the causative agent of AIDS, HIV-1, was completely removable from the plasma. Non enveloped viruses, however, proved to be more stable. The activities of clotting factors and other plasma proteins were only slightly decreased. There was no indication that the procedure led to important structural modifications of plasma proteins. The dyes are photodynamically active at concentrations much lower than those at which they are therapeutically used as antidots in the treatment of methemoglobinemia.

Cytopathogenic Effect, Viral↗
PubMed1991

Toxic epidermal necrolysis in patients receiving glucocorticosteroids.

Despite the lack of evidence of an immunologically mediated mechanism for Toxic Epidermal Necrolysis (TEN), glucocorticosteroids are frequently used for the treatment of patients afflicted with TEN. We investigated the data of 216 patients with TEN for therapy with glucocorticosteroids prior to the beginning of TEN. The data had been collected between 1984 and 1985 during the epidemiological study on severe skin reactions in West-Germany spanning the years 1981-85. 11/216 (5%) patients could be traced, who had been treated with glucocorticosteroids for at least a week prior to the first dermatological sign of TEN. Glucocorticosteroids had been administered predominantly for neurological or neurosurgical conditions. The period of treatment ranged from 1 week to several months. Doses ranging between 7.5 and 325 mg prednisolone/per day were found. There were no major differences between patients with or without steroid therapy with regard to sex, age and lethality. The observation of TEN in patients receiving therapy with glucocorticosteroids raises questions about the usefulness of treating patients with TEN with glucocorticosteroids.

Adult↗
PubMed1991

[Virus inactivation of plasma].

A procedure for the virus inactivation of single donor plasma is described. Virus inactivation is achieved by the combination of 1 mumol of phenothiazin dye, e.g. methylene blue and toluidine blue, and visible light. Using this method VSV, HSV and HIV, as well as other viruses, were inactivated. It could be shown that virus inactivation caused only a minimal reduction in the biological activities of coagulation factors and inhibitors. Furthermore, there was no indication for either neo-antigens or IgE-antibodies. In tolerance studies on dogs it was demonstrated that virus-inactivated autologous plasma caused no toxic effects.

Animals↗
PubMed1990

The cardiovascular effects of quipazine are mediated by peripheral 5-HT2 and 5-HT3 receptors in anaesthetized rats.

Quipazine (0.5-2 mg/kg i.v.) produced transient hypotension and bradycardia followed by sustained hypertension and variable effects on heart rate in anaesthetized rats. The hypotension, bradycardia and sympatho-inhibitory effects of quipazine were attenuated by bivagotomy. In bivagotomized rats, the hypertension produced by quipazine was not modified by hexamethonium or prazosin but was abolished by ritanserin (1 mg/kg i.v.). In ritanserin-treated rats, section of the carotid sinus nerves and vagus nerves or ICS 205.930 (0.1 mg/kg i.v.) abolished the hypotensive, bradycardic and sympatho-inhibitory effects of quipazine; the action of quipazine was not reproducible in these rats. Quipazine also inhibited the Bezold-Jarish reflex elicited by 5-HT (20 micrograms/kg i.v.). In ICS 205.930-treated rats, the hypertension evoked by quipazine was associated with a reduction in splanchnic nerve activity due to stimulation of baroreceptors. The renin-angiotensin system is not involved in the hypertensive response. The increase in heart rate produced by quipazine in bivagotomized rats was reduced by ritanserin and tertatolol (0.1 mg/kg i.v.) and abolished by a combination of both drugs. We conclude that the bradycardic and sympatho-inhibitory effects of quipazine result from activation of 5-HT3 receptors located in the cardiopulmonary area and of carotid body chemoreceptors. The hypertension and tachycardia are mediated by vascular and myocardial 5-HT2 receptors. No evidence was obtained for a central sympatho-excitatory effect.

Amidines↗
PubMed1990

The consequences of tubulo-interstitial changes for renal function in glomerulopathies. A morphometric and cytological analysis.

Morphometric investigation of the structures of the cortex in kidneys exhibiting various types of glomerulopathy revealed the following: 1. In various types of glomerulonephritis, diabetic glomerulosclerosis, and glomerular amyloidosis there are significant correlations between the severity of fibrosis of the renal cortical interstitium and tubular atrophy resulting from chronic interstitial inflammation, and the serum creatinine concentration, creatinine clearance, inulin clearance and PAH clearance. 2. As illustrated with the example of membranoproliferative glomerulonephritis type I, if glomerulopathy alone is present, there is no elevation of the serum creatinine concentration, even if the glomerular inflammatory changes are severe; neither are severe renal amyloidosis that is confined to the glomeruli and severe isolated diabetic glomerulosclerosis associated with elevation of the serum creatinine concentration. 3. There is a significant negative correlation between the severity of interstitial fibrosis resulting from chronic inflammation and the total number and cross-sectional area of the intertubular capillaries; i.e., the total cross-sectional area and number of capillaries per unit area decrease as the fibrosis of the cortical interstitium increases. 4. Cases of glomerulonephritis in which there is accompanying fibrosis of the renal cortical interstitium have a significantly worse long-term prognosis than those in which there is only severe glomerulitis. 5. Obliteration of the post-glomerular capillaries leads to an increase in the cross-sectional area of the glomerular capillary convolution, the morphological equivalent of an increase in intraglomerular pressure. 6. The cause of the disease of the renal cortical interstitium that may accompany the various types of glomerulonephritis is not known. It is considered possible, as a working hypothesis, that this inflammation represents a T-cell stimulated autoimmune process in which fibroblast proliferation occurs, leading to an increase in numbers of fibrocytes in the renal cortical interstitium and thus to increased production of collagen.

Creatinine↗