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Biomedical subjects

W H Hartl

Publications and source records attributed to W H Hartl.

At least 19 recordsLinked to original sources
PubMed1992

Pathophysiology of unilateral high-grade carotid artery stenosis: evaluation of intracranial haemodynamics by analysis of velocity waveforms from the middle cerebral artery.

1. Transcranial flow velocity waves were measured via Doppler sonography of the middle cerebral artery during hypo-, hyper- and normo-capnia. Applying the principle of vascular impedance, flow velocity waves were analysed in 30 young subjects, 37 elderly subjects and 18 patients with high-grade unilateral internal carotid artery disease. 2. There was evidence that the relative peak-to-peak velocity in the middle cerebral artery could serve as an index of peripheral wave reflection and cerebral resistance (CRi). The response of CRi to changes in arterial CO2 concentration (CRi reactivity) showed a clear age-dependency. However, the absolute side-to-side asymmetry of CRi reactivity (delta R) did not vary with age and could be used to define a normal range (0-4%CRi/vol.%CO2). 3. Selective angiography demonstrated no cerebral cross-flow through the anterior part of the circle of Willis in nine patients with carotid artery stenosis whose absolute delta R was above the normal range and whose CRi reactivity of the affected hemisphere was lower than that of the healthy opposite hemisphere. Conversely, another group of nine patients, whose ipsilateral CRi reactivity was higher than the contralateral CRi reactivity, demonstrated cross-flow through the anterior part of the circle of Willis. 4. delta R may be used to identify patients who have high-grade internal carotid artery stenosis and present with low cerebral vascular resistance owing to poor intracerebral collaterals.

Adult↗
PubMed1991

Comparison of pump-driven and spontaneous continuous haemofiltration in postoperative acute renal failure.

In a comparison of spontaneous continuous arteriovenous haemofiltration (CAVH) and pump-driven haemofiltration (PDHF) for acute renal failure after surgery, 116 patients admitted to a surgical intensive care unit were assigned CAVH (48) or PDHF (68). The method of assignment was that a patient was treated by PDHF if he or she was the only patient requiring treatment at that time (only one pump was available); any other patient coming to the unit would be treated by CAVH. The groups were slightly unbalanced because there were fewer simultaneous cases than expected. The main endpoints were survival rate, control of uraemia, and additional application of haemodialysis. There were no differences between the patient groups in age, duration of treatment, severity of illness, serum creatinine concentration at the start of treatment, or cause of acute renal failure. Both treatments adequately controlled uraemia and fluid overload. However, the survival rate was significantly higher with PDHF than with CAVH (6 [12.5%] vs 20 [29.4%]; p less than 0.05). The daily ultrafiltrate volume was significantly higher with PDHF than with CAVH (15.7 [95% confidence interval 13.6-17.8] vs 7.0 [6.6-7.4] l/day; p less than 0.05). The volume of ultrafiltrate in patients with ischaemic or sepsis-induced acute renal failure was correlated with the survival rate. This finding suggests that the better survival rate in the PDHF group was due to faster elimination of toxic mediators (of molecular weight 800-1000 daltons) through the filter membrane by high-volume haemofiltration.

Acute Kidney Injury↗
PubMed1991

Pericardial mass mimicking constrictive pericarditis.

Persistent pericardial hematoma due to blunt chest trauma is extremely rare. We report a case of constricted myocardium resulting from a large, partially organized hematoma in the right cardiophrenic angle. The hematoma was assumed to be caused by an occupational accident 17 years before diagnosis. Constriction could only be controlled by complete removal of the fibrous posterior capsule of the hematoma, which covered the epicardium of the right heart.

Aged↗
PubMed1991

[Improved survival rate of postoperative renal failure caused by high volume hemofiltration].

Continuous arteriovenous hemofiltration is the treatment of choice for postoperative acute renal failure (ARF). The clinical value of two different treatment modalities (spontaneous vs. pump-driven hemofiltration PDHF) were compared in two groups of patients with postoperative ARF. There were no differences in both groups regarding age, duration of treatment, severity of illness or cause of renal failure. The survival rate of patients treated with PDHF was significantly higher (29.4 vs. 12.5%). PDHF also led to a significantly larger daily ultrafiltrate volume (15.6 +/- 1.9 vs. 7.0 +/- 0.4 l/d, p less than 0.05). The accelerated elimination of toxic mediators through the filtration membrane in high-volume filtration using a pump system (PDHF) may have been responsible for the improved survival rate.

Acute Kidney Injury↗
PubMed1990

Whole body and plasma protein synthesis in exercise and recovery in human subjects.

The effect of 4 h of exercise at 40% of maximal oxygen consumption (VO2 max) on protein metabolism was assessed in normal volunteers maintained on a diet containing 42 kcal.kg-1.day-1 and either 0.9 or 2.5 g protein.kg-1.day-1. Primed constant infusions of [1,2-13C]-leucine and [15N]glycine enabled the quantitation of whole body protein turnover and also the fractional synthetic rates (FSR) of albumin, fibrinogen, and fibronectin. In subjects who did not exercise, the fractional synthetic rates (%/day) on normal and high-protein intakes, respectively, were as follows: albumin, 10 +/- 1 and 9 +/- 1; fibrinogen, 21 +/- 3 and 18 +/- 1; and fibronectin, 31 +/- 3 and 34 +/- 3. Neither exercise nor recovery had an effect of whole body protein turnover or on albumin FSR, but the FSR of fibronectin was significantly elevated at the end of exercise, and fibrinogen was significantly elevated in recovery. Dietary protein intake had no major effect on the response to exercise. Thus, in response to exercise, there is a stimulation of the synthesis of some acute phase proteins, which may be a mechanism whereby nitrogen resulting from muscle protein breakdown is spared.

Amino Acids↗
PubMed1990

Bradykinin attenuates glucagon-induced leucine oxidation in humans.

Trauma and injury are associated with accelerated protein loss. Counterregulatory hormones are possible mediators of this response. In the present study, the effect of glucagon and glucagon plus bradykinin on leucine and urea kinetics was examined in nine normal volunteers during somatostatin infusion and basal insulin replacement. Bradykinin was given because of its prostaglandin-stimulating qualities and the potential anabolic action of prostaglandins. Physiological hyperglucagonemia elicited a small but significant reduction of total leucine flux and rate of urea synthesis. Simultaneously, leucine oxidation increased by 70%. The simultaneous infusion of bradykinin did not alter glucagon-related changes in urea or leucine kinetics. Bradykinin, however, significantly attenuated the stimulation of leucine oxidation by glucagon. These results suggest that glucagon and tissue factors are involved in controlling leucine metabolism in humans.

Adult↗
PubMed1990

Effect of exercise and recovery on muscle protein synthesis in human subjects.

Previous studies using indirect means to assess the response of protein metabolism to exercise have led to conflicting conclusions. Therefore, in this study we have measured the rate of muscle protein synthesis in normal volunteers at rest, at the end of 4 h of aerobic exercise (40% maximal O2 consumption), and after 4 h of recovery by determining directly the rate of incorporation of 1,2-[13C]leucine into muscle. The rate of muscle protein breakdown was assessed by 3-methylhistidine (3-MH) excretion, and total urinary nitrogen excretion was also measured. There was an insignificant increase in 3-MH excretion in exercise of 37% and a significant increase (P less than 0.05) of 85% during 4 h of recovery from exercise (0.079 +/- 0.008 vs. 0.147 +/- 0.0338 mumol.kg-1.min-1 for rest and recovery from exercise, respectively). Nonetheless, there was no effect of exercise on total nitrogen excretion. Muscle fractional synthetic rate was not different in the exercise vs. the control group at the end of exercise (0.0417 +/- 0.004 vs. 0.0477 +/- 0.010%/h for exercise vs. control), but there was a significant increase in fractional synthetic rate in the exercise group during the recovery period (0.0821 +/- 0.006 vs. 0.0654 +/- 0.012%/h for exercise vs. control, P less than 0.05). Thus we conclude that although aerobic exercise may stimulate muscle protein breakdown, this does not result in a significant depletion of muscle mass because muscle protein synthesis is stimulated in recovery.

Adult↗
PubMed1990

Effects of kinins on glucose metabolism in vivo.

Current concepts of the physiological importance of the kinin/prostaglandin system view these tissue factors as part of a defense system, which protects tissues from potentially noxious factors, such as hypoxia or destructive inflammatory reactions. This kinin-triggered defense reaction includes an improvement in cellular energy metabolism. The latter is brought about in peripheral tissues by an increased availability of glucose for anaerobic and aerobic glycolysis, whereas in liver tissue, energy-consuming reactions such as gluconeogenesis are attenuated. There is evidence that such favorable effects can also be produced in man when kinins are administered systemically. Prostaglandins are most likely the second messengers of kinin-induced metabolic effects. Thus, it may be advantageous to increase the availability of kinins either by exogenous infusion or by inhibiting endogenous degradation during postoperative stress or in diseases such as diabetes mellitus, in which glucose metabolism is severely disturbed.

Blood Glucose↗
PubMed1990

Kinin/prostaglandin system: its therapeutic value in surgical stress.

Multiple system organ failure as a consequence of injury or sepsis remains the major reason for death in critically ill patients. One of the treatment concepts that has recently attracted clinical attention is the administration of kinins and prostaglandins (PGs). On the basis of experimental data, there is reason to believe that these compounds may have the potential to manipulate favorably certain processes and mechanisms (such as inflammatory or ischemic reactions) thought to be important in the pathophysiology of surgical stress. However, thus far, information on those effects in humans is still scarce. On the other hand, administration of kinins and PGs is technically possible and can be performed safely, even in intensive care patients. Therefore, different techniques, effects, and side-effects of kinin/PG therapy deserve clinical testing. It remains to be seen whether this concept will be useful in the treatment of critically ill surgical patients.

Animals↗
PubMed1989

Glucagon and hepatic glucose production: modulation by low-dose bradykinin infusion.

The effect of a low-dose bradykinin (BK) infusion (30 ng/kg min) on glucagon-induced hepatic glucose production and glucose cycling was studied in five normal volunteers. Studies were performed during constant insulin concentration as achieved by simultaneous somatostatin infusion and insulin replacement. In the basal period glucagon was infused at a rate of 0.5 ng/kg min. Then, glucagon infusion rate was increased to 3 ng/kg min to test the response to hyperglucagonemia. In a second set of experiments BK was infused concomitantly with the high dose glucagon. Each subject served as his own control. BK infusion did not prevent the glucagon-induced rise in hepatic glucose production and glucose cycling. However, at a later stage BK accelerated the negative feedback mechanisms activated by glucagon (decrease in hepatic glucose production) significantly. These findings suggest that intravenous BK may interact with mechanisms involved in the down-regulation of hepatic glucagon effects.

Adult↗
PubMed1989

Ticarcillin/clavulanate in the treatment of severe peritonitis.

A prospective study was performed on 50 consecutive patients with secondary peritonitis. All patients received ticarcillin/clavulanate 5.2 g three times daily as initial antibiotic therapy. In 30 patients a primary perforation was found in the gastro-intestinal tract and 20 had post-operative peritonitis. In two thirds of the patients a diffuse peritonitis was found which affected the whole abdomen. Thirty-six patients underwent one or two laparotomies and 11 patients had more than three laparotomies. Subsequently, 17 patients died. The cause of death was a therapeutic failure as a result of the surgical procedure in ten patients (nine patients with persisting intestinal fistulae, one patient with bleeding), whereas in seven cases antibiotic therapy failed. Micro-organisms found in the latter patients were producers of type 1 beta-lactamase (Pseudomonas aeruginosa, Enterobacter sp., Citrobacter sp., Serratia marcescens) and enterococci. Ticarcillin/clavulanate is characterized by its broad antimicrobial spectrum against anaerobic and aerobic bacteria and seems, therefore, to be well suited for initial chemotherapy in patients with diffuse peritonitis.

Adult↗