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Biomedical subjects

M Baum

Publications and source records attributed to M Baum.

At least 415 records · Page 23Linked to original sources
PubMed1986

Lack of a direct effect of atrial natriuretic factor in the rabbit proximal tubule.

Whole animal clearance studies and in vitro microperfusion studies were performed to examine the effect of atrial natriuretic factor (ANF) on the rabbit proximal tubule. Infusion of ANF into rabbits resulted in an increase in glomerular filtration rate and a natriuresis and diuresis. To determine whether ANF has a direct proximal tubule effect to account for part of the observed natriuresis, proximal convoluted tubules (PCT) and proximal straight tubules (PST) were perfused in vitro. Addition of 10(-9) M ANF, a concentration recently measured in vivo during volume expansion, to the bathing solution of PCT caused no significant change in volume absorption. Addition of a pharmacological concentration of ANF (10(-7) M) to either the bathing solution or the luminal perfusate of PCT resulted in no change in volume absorption. When added to the bathing solution of PST, 10(-7) M ANF did not have an effect on volume absorption. ANF did not affect the transepithelial potential difference in any protocol. In conclusion, these data show that ANF does not affect transport directly in the proximal tubule.

Animals↗
PubMed1986

Antibiotic-associated interstitial nephritis and nephrotic syndrome.

The combination of interstitial nephritis and minimal-change nephrotic syndrome has been well described in adults receiving nonsteroidal anti-inflammatory agents. The association of interstitial nephritis and minimal-change nephrotic syndrome has recently been described in 1 adult patient receiving ampicillin and in 1 patient receiving rifampin. We describe an 8-month-old child who developed reversible interstitial nephritis and minimal-change nephrotic syndrome while taking antibiotics.

Amoxicillin↗
PubMed1985

Peritubular protein modulates neutral active NaCl absorption in rabbit proximal convoluted tubule.

To assess directly the effect of increasing and decreasing peritubular protein concentration on active NaCl absorption, rabbit proximal convoluted tubules were perfused with a high-chloride solution simulating late proximal tubular fluid and bathed in a similar solution containing 0, 6, or 10 g/dl albumin. A direct examination of the active component of NaCl absorption was ensured by 1) the reduction of luminal solutes other than NaCl (no glucose or alanine and only 5 mM HCO-3), and 2) the use of perfusate and bathing solutions in approximate Donnan equilibrium, so that electrochemical driving forces responsible for passive net NaCl absorption are eliminated. When bathing solution albumin concentration was reduced from 6 to 0 g/dl, volume absorption (Jv) was reduced significantly from 0.39 +/- 0.07 to 0.22 +/- 0.08 nl X mm-1 X min-1. When bathing solution albumin concentration was increased from 6 to 10 g/dl, Jv increased significantly from 0.26 +/- 0.04 to 0.37 +/- 0.04 nl X mm-1 X min-1. When proximal convoluted tubules were bathed in 0, 6, or 10 g/dl albumin at 20 degrees C, Jv was not different from zero in all periods, confirming that changes in bathing solution albumin require the presence of active transport to influence NaCl absorption. The transepithelial potential difference attributable to active transport was not different from zero in all periods of all protocols, demonstrating that active NaCl absorption was electroneutral. In conclusion, these data show directly that peritubular protein concentration modulates neutral active NaCl absorption in the rabbit proximal convoluted tubule.

Absorption↗
PubMed1985

[Effect of high-frequency ventilation on intracranial pressure].

The influence of respiratory frequency, tidal volume, inspiratory flow and ratio of inspiratory/expiratory time on ventilator-related intracranial pressure (ICP) fluctuations was studied in six patients with severe brain trauma. ICP fluctuations were found to be markedly reduced at frequencies of 20/min and usually eliminated at 30/min. We found an exponential correlation between ICP fluctuations and respiratory frequency, but there was no correlation between tidal volume and ICP. Central venous pressure amplitudes were found to be in linear correlation with respiratory frequency and tidal volumes as well. The amplitude of respiratory ICP fluctuations correlates with the length of expiratory time. Our findings demonstrate that artificial ventilation without ventilator-related fluctuations in ICP ("brain-protective" ventilation) may be performed by conventional volume-constant, time-cycled ventilators. To assess the therapeutic relevance of eliminating respirator-related fluctuations of the ICP course in brain-injured patients, we suggest that frequencies of 25-30/min and tidal volumes of 6-9 ml/kg body weight should be used.

Brain Injuries↗
PubMed1984

Intraoperative application of high-frequency ventilation.

High-frequency pulsation (HFP), a modified high-frequency jet ventilation (HFJV) technique, was applied intraoperatively as an alternative to conventional inter mittent positive-pressure ventilation in 16 patients undergoing major thoracic operations. Gas exchange and hemodynamic stability were maintained at a frequency of 300 cycle/min. Surgical maneuvers were easier because the lungs were almost completely immobilized.

Adult↗
PubMed1984

Evidence for neutral transcellular NaCl transport and neutral basolateral chloride exit in the rabbit proximal convoluted tubule.

The electrical nature of active NaCl transport and the significance of a basolateral membrane chloride conductance were examined in isolated perfused rabbit proximal convoluted tubules (PCT). PCT were perfused with a high chloride solution that simulated late proximal tubular fluid and were bathed in an albumin solution that simulated rabbit serum in the control and recovery periods. The electrical nature of NaCl transport was examined by bathing the tubules in a high chloride albumin solution where there were no anion gradients. Volume reabsorption (Jv) during the control and recovery period was 0.56 and 0.51 nl/mm X min, respectively, and 0.45 nl/mm X min when the tubules were bathed in a high chloride bath. The transepithelial potential difference (PD) during the control and recovery periods averaged 2.3 mV, but decreased to 0.0 mV in the absence of anion gradients, which indicated that NaCl transport is electroneutral. Further evidence that NaCl transport is electroneutral was obtained by examining the effect of addition of 0.01 mM ouabain in PCT perfused and bathed with high chloride solutions. The Jv was 0.54 nl/mm X min in the control period and not statistically different from zero after inhibition of active transport. The PD was not different from zero in both periods. Two groups of studies examined the role of basolateral membrane Cl- conductance in NaCl transport. First, depolarizing the basolateral membrane with 2 mM bath Ba++ did not significantly affect Jv or PD. Second, the effect of the presumptive Cl- conductance inhibitor anthracene-9-CO2H was examined. Anthracene-9-CO2H did not significantly affect Jv or PD. In conclusion, these data show that NaCl transport in the PCT is electroneutral and transcellular and provide evidence against a significant role for basolateral membrane chloride conductance in the rabbit PCT.

Animals↗
PubMed1983

Patients surviving 10 years of hemodialysis.

Experience with 37 patients surviving 10 years of hemodialysis therapy was reviewed. These patients were compared with 103 patients who began hemodialysis between 1967 and 1971 and who subsequently died. Males had an excess risk of death. Patients with polycystic kidneys survived longer. There was more uncontrolled hypertension among a control group than in 10-year survivors. In survivors, the hematocrit level increased over time and averaged 30.4 percent at 10 years. Over 10 years, many complications arose including parathyroidectomy (24), pericarditis (13), gastrointestinal bleeding (11), myocardial infarction (10), septicemia (eight), and active tuberculosis (six). Despite complications, most patients are now stable. Between their eighth and 10th years they required an average of only one hospitalization with a mean stay of 9.7 days. Eighteen patients were not hospitalized. Excluding housewives, 67 percent of patients between ages 20 and 59 years are employed full-time and 10 percent part-time. Patients surviving 10 years are not progressively deteriorating and may look to the future with cautious optimism.

Adolescent↗