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Biomedical subjects

G Heinz

Publications and source records attributed to G Heinz.

At least 109 records · Page 6Linked to original sources
PubMed1990

Quantitative evidence of peripheral conversion of angiotensin within the human leg: effects of local angiotensin-I administration and angiotensin-converting enzyme inhibition on regional blood flow and angiotensin-II balance across the leg.

The renin-angiotensin system relevantly contributes to the maintenance of systemic vascular tone and there is experimental evidence that large amounts of angiotensin-converting enzyme (ACE) are present in peripheral vascular tissues, including resistance vessels. To determine and quantify peripheral vascular conversion of angiotensin-I (ANG-I) to angiotensin-II (ANG-II) across the human leg, the response of regional blood flow to local regional intra-arterial infusion of ANG-I and change in associated ANG-II balance were evaluated during ANG-I infusion and following additional ACE inhibition. Ten sodium-loaded healthy men were enrolled in the study. Following cannulation of both femoral arteries and the right femoral vein, leg blood flow was determined (indocyanine-green dye-dilution method) at baseline conditions and during constant intra-arterial infusion of haemodynamically ineffective doses of ANG-I as well as following concomitant intra-arterial administration of low doses of the non-sulfhydril ACE inhibitor cilazapril. From the transfemoral arterio-venous differences in ANG-II plasma concentrations and the corresponding regional blood (plasma) flow, the ANG-II balance across the leg was calculated. Systemic blood pressure did not change throughout the trial, indicating that no major systemic effects were present during ANG-I infusion or concomitant ACE inhibition. Moreover, arterial ANG-II plasma concentrations were not significantly changed by ANG-I infusion. Leg blood flow decreased to below baseline values following ANG-I infusion, increasing again then in a dose-dependent manner during concomitant cilazapril administration. The calculated baseline ANG-II balance across the leg revealed a net extraction in 6 out of 10 subjects and a net ANG-II formation in 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Lack of effect of tenoxicam on dynamic responses to concurrent oral doses of glucose and glibenclamide.

1. In a single-blind, placebo controlled study the influence of tenoxicam on responses of glucose, insulin and C-peptide to oral doses of glucose and glibenclamide was examined in 16 healthy male volunteers. 2. The subjects received once daily doses of 2.5 mg glibenclamide for 12 days. From day 5 through 12 eight subjects received concomitantly 20 mg tenoxicam once daily and the remaining eight subjects received placebo. 3. On days 1, 4, 5 and 12 glibenclamide was taken with 75 g glucose and blood glucose, serum insulin and C-peptide were measured over 5 h. Plasma levels of glibenclamide and tenoxicam (where appropriate) were followed over 10 h. 4. Characteristic parameters of blood glucose and insulin and C-peptide responses did not change significantly with time (day) and there was no difference between both treatment groups. 5. Baseline insulin increased from 11.7 mu l-1 on day 1 to 15.6 mu l-1 on day 4 (P = 0.009), likewise baseline C-peptide increased from 478 pmol l-1 to 530 pmol l-1 (P = 0.05), but there was no further change in the subsequent treatment period. 6. The AUC of the glibenclamide plasma concentration-time curve did not show changes with time or differences between treatment groups. The mean (s.d.) oral clearance of tenoxicam was 2.5 (1.5) ml min-1 and appeared slightly higher than in previous studies. 7. It was concluded that tenoxicam did not affect overall glycoregulation in healthy subjects under glibenclamide steady state conditions.

Adult↗
PubMed1990

Clinical and electrophysiologic correlates of sinus node dysfunction after orthotopic heart transplantation. Observations in 42 patients.

We assessed incidence and course of postoperative SN dysfunction in 42 cardiac transplant recipients. RHY, HR and CSNRT were compared in distinguishing between persistent (9 of 42 patients) and transient (11 of 42) SN dysfunction. Persistent SN dysfunction was distinguished by a significantly lower HR (day 14: 46.2 +/- 12 vs 67 +/- 19 bpm; day 21: 40.3 +/- 21 vs 70.8 +/- 16 bpm; p less than 0.05, respectively) and by RHY: postoperative AS (3 of 42) was found only in patients whose SN dysfunction persisted while patients with SR but prolonged CSNRT more often had transient impairment (6 of 42 vs 2 of 42); CSNRT, in contrast, is unlikely to be useful in distinguishing between transient and persistent SN dysfunction since exceptionally long CSNRTs (11,340 ms. 12,080 ms) occurred in patients with both types. Ischemic times were significantly longer in patients with transient impairment when compared with the group with normal SN function (155.1 +/- 36 vs 109.2 +/- 36 min, p less than 0.05) but did not differ significantly in patients with persistent SN dysfunction (124.8 +/- 32 min). Thus, (1) SN dysfunction after cardiac transplantation is common but most often transient; (2) RHY and HR are adequate follow-up parameters and best predictors of long-term SN function; (3) SN dysfunction after transplantation has important clinical implications given the unreliability of lower pacemakers to take over in 3 patients; (4) transient SN dysfunction is related to duration of ischemia during hypothermic preservation whereas pathogenesis of persistent SN dysfunction remains to be elucidated.

Adult↗
PubMed1989

Ciprofloxacin (intravenous/oral) versus ceftazidime in lower respiratory tract infections.

The efficacy and safety of intravenous ciprofloxacin was compared with intravenous ceftazidime in 80 hospitalized patients with lower respiratory tract infection. There were 40 patients in each treatment group. Patients and physicians were blinded to the randomized scheme for treatment groups until patient consent was obtained. The 37 evaluable ciprofloxacin-treated patients received 200 mg every 12 hours intravenously as initial therapy and 29 completed their course receiving oral ciprofloxacin. The 34 evaluable ceftazidime-treated patients received 1 to 2 g intravenously every eight to 12 hours. The two groups did not differ with respect to patient age, infection severity, and admitting diagnosis. Clinical outcomes were similar with greater than 95 percent of treatments in each group being successful. Headache was the most commonly reported complaint (four patients) in the ciprofloxacin group. Three patients experienced substantial increases in serum theophylline concentrations while receiving ciprofloxacin. The predominant pathogens isolated were Haemophilus influenzae and Pseudomonas aeruginosa, and susceptibility rates for all organisms were similar for both drugs. The mean peak serum concentration at steady state while receiving intravenous ciprofloxacin was 2.3 micrograms/ml, and the mean trough concentration was 0.5 micrograms/ml. Patients randomly assigned to ciprofloxacin therapy received 2.6 fewer days of intravenous antibiotic therapy than those receiving ceftazidime. This 80-patient comparative trial demonstrates that ciprofloxacin and ceftazidime are similar in efficacy and safety when treating gram-negative lower respiratory tract infections. There appears to be potential for cost-reducing benefits through decreased length of intravenous therapy and earlier hospital discharge.

Administration, Oral↗
PubMed1989

Reduction of postprandial blood glucose by the alpha-glucosidase inhibitor Miglitol (BAY m 1099) in type II diabetes.

The dose-dependency of the effects of the alpha-glucosidase inhibitor Miglitol (Bay m 1099) was investigated in 8 Type II diabetic patients. Administration of increasing doses of Miglitol once daily in the morning on four consecutive days concomitantly with a standardized meal containing 50 g starch led to a dose-dependent reduction in the maximal increase in the postprandial blood glucose level and in postprandial incremental AUC of blood glucose. The latter was significant for 50, 100, 75 and 200 mg Miglitol. Bay m 1099 also markedly retarded the appearance of the peak postprandial blood glucose concentration, which indicates delayed carbohydrate absorption. Serum insulin levels, documented as incremental AUCs of the serum insulin excursions, were not reduced dose dependently, because of the impaired insulin secretory capacity of the patients.

1-Deoxynojirimycin↗
PubMed1989

Effects of ACE inhibition with cilazapril on splanchnic and systemic haemodynamics in man.

1. There is recent experimental evidence that the renin-angiotensin-system may play an essential role in producing splanchnic vasoconstriction. However, controversy exists as to the influence of ACE inhibition on splanchnic haemodynamics in man. We therefore investigated whether cilazapril, a structurally new and long-acting ACE inhibitor, interacts with angiotensin I-dependent changes in splanchnic haemodynamics in man, using an experimental model. 2. The effects of cilazapril on angiotensin I-induced splanchnic and systemic haemodynamics were studied in seven normotensive men using the hepatic venous catheter technique (indocyanine-green dye), right-heart catheterisation (thermodilution method), intra-arterial blood pressure monitoring and systolic time-intervals. Dose-responses to angiotensin I were determined under control conditions and 60 min after ACE inhibition with 5 mg oral cilazapril. Angiotensin I was infused intravenously at constant rates in an increasing dose-sequence until systolic blood pressure was greater than 30 mm Hg. 3. ACE inhibition with cilazapril did not change basal splanchnic or systemic haemodynamics to any relevant extent. The angiotensin I dependent increase in systemic and pulmonary resistance and pulmonary capillary wedge pressure was attenuated by cilazapril, as indicated by the shift of the dose-response curves to the right. In the splanchnic vascular bed angiotensin I dose-dependently increased splanchnic vascular resistance and also wedge hepatic venous pressure and decreased splanchnic blood flow. These angiotensin I induced haemodynamic changes were clearly suppressed by cilazapril. The angiotensin I dose needed to produce a 30% increase in splanchnic vascular resistance, given as mean and s.e. mean, was 1.7 +/- 0.3 micrograms min-1 during control-trials vs 7.3 +/- 1.3 micrograms min-1 after ACE inhibition with cilazapril (P less than 0.001). 4. We conclude that, in man, the influence of cilazapril on acute angiotensin I-mediated haemodynamic responses is present in the splanchnic vascular bed, and that the overall effects of cilazapril are consistent with both arterial and venous effects of the ACE inhibitor. Cilazapril effectively counteracts angiotensin I-induced splanchnic vasoconstriction.

Adult↗
PubMed1987

The P300 component of event-related potentials in schizophrenic patients.

In a pilot study, the P300 component of the ERP subsequent to competitive visual stimulation was examined in 12 schizophrenic patients (paranoid hallucinatory schizophrenia in partial remission, neuroleptic medication). In the competitive stimulation with a varying information content of the non-target stimuli, healthy probands showed a distinct increase in the amplitude of the P300 components according to a in the frequency of the non-target stimuli. The P300 components during these changing stimulatory conditions remained constant in the schizophrenic patients. This reduction in the reactivity of the P300 component subsequent to an increasing information content of the non-target stimuli can be interpreted as a disturbance in the selective information processing. The ability to adequately react to the information content of irrelevant stimuli appears to be reduced in the schizophrenic patients we examined.

Adult↗
PubMed1979

The anti-nociceptive effect of reserpine and haloperidol mediated by the nigro-striatal system: antagonism by naloxone.

Reserpine (10 mg/kg) and haloperidol (2 mg/kg) injected intraperitoneally increased the reaction time of the tail-flick response in intact but not in pre-nigrally decerebrate or spinal rats. The antinociceptive effect of both drugs was antagonized by intraperitoneal injections of dopa (100 mg/kg), apomorphine (2 mg/kg) or naloxone (1 mg/kg) as well as by bilateral micro-injections into the caudate nuclei of apomorphine (100 microgram and 20 microgram) and naloxone (10 microgram). It is concluded that the nigrostriatal feedback system is involved in the anti-nociceptive effect of reserpine and haloperidol.

Analgesics↗
PubMed1978

The effect of substantia negra stimulation and morphine on alpha-motoneurones and the tail-flick response.

Rats were used to study the effect of unilateral stimulation of the substantia nigra on the reflex discharge of alpha-motoneurones and on the reaction time of the tail-flick response. In preparations with prenigral decerebration, nigral stimulation facilitated monosynaptic alpha-reflex activity, whilst gamma-reflex activity remained unchanged. The facilitation of monosynaptic alpha-reflex activity was reduced by naloxone (1 mg/kg); morphine (2 mg/kg) did not change the number of alpha-reflex discharges, but it reduced the alpha-reflex latency, enhanced the effect of nigral stimulation on the latency and abolished the effect of naloxone on nigral facilitation. Nigral stimulation prolonged the reaction time of the tail-flick response in rats with an intact brain and after prenigral decerbration. Naloxone did not influence the anti-nociceptive effect of nigral stimulation, whilst morphine enhanced it in rats with an intact brain. The anti-nociceptive effect exerted by morphine in animals with an intact brain was abolished by prenigral decerbration, and an additional spinalization restored it. Inactivating the nigral neurones by unilateral microinjections of procaine or GABA into the substantia nigra depressed the nociceptive reflex. It is concluded that (1) activation of nigral neurones influenced mono- and polysynaptic reflexes in a reciprocal fashion by a pathway descending via brain stem relays to the spinal cord, (2) inactivation of nigral neurones produced similar changes in reflex activity by altering the function of the nigro-striatal feedback system, the outlet from the system to the spinal cord not being the substantia nigra, (3) morphine influenced the nociceptive reflex by an action at different levels of the central nervous system.

Animals↗