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Biomedical subjects

N Fineberg

Publications and source records attributed to N Fineberg.

50 records · Page 3Linked to original sources
PubMed1987

Effect of inorganic phosphate in hypoxemic chronic obstructive lung disease patients during exercise.

We have shown that normal subjects exercise more efficiently with increased plasma phosphate, presumably due to decreased hemoglobin-oxygen affinity and thus enhanced tissue O2 extraction. We subjected nine stable hypoxemic COLD patients to exercise at 0 (control), 24 (experimental) and 48 hrs (recovery) after phosphate infusion. Baseline variables were identical for each time period. Exercise responses at 0 and 48 hours were also indistinguishable. Exercise response at 24 hrs differed from those at 0 and 48 hours as follows: widening of A-V O2 content difference was more pronounced (28 +/- 6 vs 15 +/- 6 ml/L, p less than 0.03) and the increment in tissue O2 extraction was larger (14 +/- 3 vs 8 +/- 3 percent, p less than 0.03). P50 and related variables did not change during the course of the study. Thus, like normal subjects, hypoxemic patients stimulated with phosphate administration can exercise perhaps more efficiently; but, in contrast to normal subjects, this effect cannot be attributed to changes in hemoglobin-oxygen affinity. These data suggest that phosphate administration may be beneficial in hypoxemic states where adequate tissue oxygenation cannot be achieved by other more conventional methods. The mechanism of this effect remains to be elucidated.

Female↗
PubMed1986

Encainide for treatment of supraventricular tachycardias associated with the Wolff-Parkinson-White syndrome.

Thirty-three patients with supraventricular tachycardia associated with the Wolff-Parkinson-White syndrome were treated with encainide for 26 months (mean). Encainide at a mean dosage of 187 mg/day abolished or markedly decreased episodes of palpitations in 24 of 33 (73%), and no patient had syncope or required cardioversion while receiving the drug. Encainide was well tolerated and was discontinued in only 2 patients because of side effects (6%). Only 1 patient (3%) had a proarrhythmic effect while taking encainide (ventricular tachycardia). Fourteen of 16 patients (88%) with atrial fibrillation continue receiving encainide. Episodes of palpitations have been abolished or markedly decreased and no patient has had syncope or required cardioversion. All 14 of these patients had either anterograde block in the accessory pathway during atrial fibrillation or greater than or equal to 75 ms increase in the shortest R to R interval formed by 2 preexcited QRS complexes. Encainide prolonged refractory periods of the atrial (p = 0.064) and ventricular (p = 0.061) muscle. It prolonged the cycle length at which 1:1 conduction of the accessory pathway in both the anterograde and retrograde directions occurred (both, p less than 0.001). Induction of atrioventricular-reciprocating tachycardia (AVRT) was prevented in 36% of patients at repeat electrophysiologic study. The AVRT cycle length increased 112 ms (mean, p less than 0.001) in those patients in whom AVRT was still inducible. The loss of delta waves recorded with the 12-lead scalar electrocardiogram during encainide therapy was a significant predictor of anterograde accessory pathway block (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Diabetic foot infections. Bacteriologic analysis.

Diabetic patients with foot infections were prospectively evaluated over a two-year period. Cultures from reliable specimens avoiding contamination with foot ulcers were obtained in 54 infectious episodes. Staphylococcus species, Enterococcus species, Corynebacterium species, and various species of Enterobacteriaceae were commonly isolated. Common anaerobic isolates included Peptostreptococcus magnus, Peptostreptococcus prevotii, and Bacteroides species. Results of cultures from 94 unreliable specimens were similar. Results of reliable and unreliable specimens obtained simultaneously in 26 patients agreed in seven (27%), but antibiotics selected for organisms isolated from unreliable specimens would have adequately covered pathogens found in the reliable culture in 24 (93%). Diabetic foot infections usually involve mixed bacterial flora, including aerobic, facultatively anaerobic, and anaerobic microorganisms. Specimens should be obtained from infected tissue that does not communicate directly with the foot ulcer if possible. If such specimens are not available, cultures of purulent exudate within the foot ulcer or soft-tissue sinuses may provide useful information on which to base decisions about antibiotic therapy. Broad-spectrum beta-lactam antibiotics or a combination of antibiotics active against facultatively anaerobic cocci and bacilli as well as anaerobes provide the best empirical antimicrobial coverage in these patients.

Abscess↗
PubMed1985

Tocolytic and hemodynamic effects of nifedipine in the ewe.

The ability of the calcium antagonist nifedipine to inhibit uterine contractions during labor and in the postpartum period was measured in the ewe. The hemodynamic effects of tocolytic doses of this drug were measured and compared with the hemodynamic effects of equivalent doses of ritodrine. Intravenous nifedipine was found to be a potent tocolytic agent that completely inhibited uterine activity even in advanced labor when administered at infusion rates that resulted in only mild hemodynamic effects. At tocolytically similar infusion rates nifedipine produced significantly less increase in maternal heart rate than did ritodrine.

Animals↗
PubMed1985

Prediction of survival in progressive systemic sclerosis by multivariate analysis of clinical features.

The records of 64 patients with progressive systemic sclerosis (PSS) were reviewed. More than 100 items from the patient's history, physical examination, and laboratory tests were encoded. A two-tailed Gehan's test was used to evaluate the effect of each variable on patient survival. Variables significant at the 0.05 level were then analyzed simultaneously, using the Cox regression model, in order to determine which clinical features are most predictive of survival in PSS. By Cox regression, the presence of an S3 gallop and advanced age at onset of PSS related negatively to survival. The relative risk of death for a patient with an S3 gallop was 5.44 (ratio of risk) times that for a patient without an S3 gallop, and the risk of death for a 70-year-old patient at disease onset was 20 times that of a 20-year-old patient at disease onset. In addition, when patient selection was taken into account, corticosteroid administration had a significant effect, and seemed to actually shorten survival. Although one of the factors, age at onset, is not modifiable, the presence of either variable should alert the clinician to the patient being at high risk for short survival. The application of this technique should also prove helpful in analyzing the efficacy of various proposed therapies.

Adolescent↗
PubMed1984

Prolongation of the QT interval induced by probucol: demonstration of a method for determining QT interval change induced by a drug.

Sudden death has occurred in monkeys fed large doses of probucol, a cholesterol-lowering drug, given in combination with an atherogenic diet. These monkeys develop prolonged QT intervals and high serum levels of probucol. We investigated the effect of probucol on QT interval and the incidence of ventricular ectopy during a double-blind placebo-controlled study in 16 patients with less than 600 premature ventricular complexes (PVCs) per day and a corrected QT interval of less than 0.44 second. Seven patients received probucol and nine patients received placebo. Three 24-hour continuous ECG recordings were obtained prior to entry into the study and three additional recordings were obtained after 6 months of drug or placebo therapy. A 15-second ECG tracing was sampled from the continuous ECG recording every 30 minutes and, for the group, 15,000 QT intervals were measured permitting construction of QT versus R-R regression lines for each patient before and during therapy. Comparison of the regression lines revealed that the measured QT interval prolonged 20 +/- 18 msec during the awake state and 24 +/- 20 msec during sleep (mean + standard deviation) at matched heart rates in the seven patients receiving probucol (p less than 0.01). Using Bazett's formula to correct for rate, corrected QT interval prolonged 22 +/- 23 msec in the awake state and 20 +/- 18 msec in the asleep state (p less than 0.01). In probucol treated patients QT interval prolongation was directly related to increasing probucol plasma levels (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Effect of decreased O2 affinity of hemoglobin on work performance during exercise in healthy humans.

A reduction in O2 affinity of hemoglobin should increase tissue oxygenation or maintain tissue oxygenation and at the same time spare cardiac work. Large, sustained reductions in O2 affinity of hemoglobin are induced best by primary (non-Bohr effect) stimulation of red blood cell 2,3-diphosphoglycerate (DPG) caused by a dual, cumulative effect on O2 affinity for hemoglobin, direct, from DPG itself, and indirect, from DPG-induced red blood cell acidosis. In an attempt to induce significant, sustained reductions in O2 affinity of hemoglobin by primary DPG stimulation, six normal humans were given a diphosphonate (etidronate disodium [Didronel] 20 mg/kg/day p.o.) followed by infusion of 10% fructose (0.5 L/hr for 3 hours) with added phosphate (0.28 mmol/kg/hr) and, subsequently, fructose-phosphate by itself. Participants underwent exercise testing (bicycle ergometer) and cardiopulmonary parameters were measured before and after administration of Didronel plus fructose-phosphate infusion, as well as before and after fructose-phosphate infusion alone. The sum of DPG and adenosine triphosphate as well as the P50 increased significantly after infusion of fructose-phosphate with and without prior administration of Didronel. DPG-ATP correlated closely with P50. When P50 was elevated, the cardiac index at high work load was lower than when P50 was normal (with comparable O2 consumption); changes in P50 correlated inversely with changes in cardiac index. Thus, with reduced O2 affinity of hemoglobin, participants could perform at comparable work loads and utilize the same amount of O2 with less cardiac work. Future studies should include adapting these findings to states of O2 deficit.

2,3-Diphosphoglycerate↗
PubMed1982

Acute effects of hypoxia on renal and endocrine function in normal humans.

The effects of hypoxia upon renal and endocrine function are unclear. Normal water-loaded subjects were exposed to hypoxia for 1 h (inspired PO2 = 74 Torr) in a decompression chamber (5,100 m, n = 8) or by breathing 10.5% oxygen at ambient pressure (n = 4). In four of eight subjects exposed to hypobaric hypoxia: urine flows (V) decreased (mean = 56%), urine osmolality increased (340%), plasma arginine vasopressin (AVP) increased (2,700%), plasma cortisol increased (256%), and mean blood pressure (BP) decreased (18%). V correlated inversely with AVP (r = 0.71, P less than 0.01) while AVP increases correlated with falls in mean BP (r = 0.72, P less than 0.05). Similar results were observed in the subjects exposed to normobaric hypoxia. Plasma aldosterone fell in the four subjects who maintained V on exposure to hypobaric hypoxia, but plasma renin activity did not change. In both groups prolactin levels were variable and solute and creatinine excretion were unchanged. No changes were observed in controls or in subjects exposed to hypobaria alone. Acute hypoxic exposure may produce significant hypotension with consequent increased AVP secretion resulting in diminished V.

Adolescent↗
PubMed1980

Factors affecting sleep spindle activity during infancy.

Sleep spindle activity was evaluated in 32 twins at 52 weeks postconceptional age. Significantly increased mature spindle activity was seen in infants born at older gestational ages, in femals, and in infants who were stressed by intra-uterine growth retardation or with mild postnatal respiratory illness.

Cerebral Cortex↗
PubMed1979

Effects of volume expansion and contraction in normotensive whites, blacks, and subjects of different ages.

We studied the blood pressure, natriuretic, kaliuretic and humoral responses of 347 normal subjects after volume expansion and volume contraction to examine possible differences among whites, blacks and subjects of different ages. According to outpatient 24-hour urine collections, blacks excreted less sodium and potassium than whites. After similar states of sodium intake were achieved among all subjects, 2 liters normal saline were given i.v. Blacks and subjects greater than or equal to 40 years excreted less sodium than whites or subjects less than 40 years, over a 24-hour period. In addition, blacks excreted less potassium. The delay in sodium excretion occurred during the first 12 hours after the salt load. Blacks had a greater suppression of plasma renin activity than whites 24 hours after saline. Blacks also had higher blood pressures than whites after saline administration; their pressure remained elevated until furosemide was given. Furosemide, 120 mg over 24 hours, evoked greater natriuresis, but less kaliuresis in blacks than in whites. The greater prevalence of hypertension in both blacks and older subjects may be related to relatively blunted natriuretic responses when these groups engage in the high sodium-low potassium intake characteristic of our society.

Adolescent↗
PubMed1977

The sleep state characteristics of apnea during infancy.

The sleep state characteristics of infant sleep apnea were studied in 36 twins examined by polygraphy at 40, 44, and 52 weeks after conception. The definition of sleep apnea is dependent upon the length of apnea, sleep state, and post-conceptional age. None of the infants had apnea longer than 20 seconds and apnea of 10 seconds or longer was uncommon. The attack rates for apneas 2 to 4.9 seconds long were highest in REM and lowest in qliet sleep. The attack rates for apneas 5 to 9.9 seconds long were equal in REM and indeterminate and lowest in quiet sleep. The percentage of infants with apnea of 10 seconds or longer at 40 weeks was highest in REM (27%) and indeterminate sleep (42%) and lowest in quiet sleep (12%). At 52 weeks, apnea 10 seconds or longer during REM decreased to 0%. The effect of maturation on apnea varies with sleep state. Over the period from 40 to 52 weeks, quiet sleep apnea was unchanged and indeterminate sleep apnea decreased only between 40 and 44 weeks. Although REM apnea 2 to 4.9 seconds long was unchanged, REM apnea 5 to 9.9 seconds long decreased between 40 and 44 weeks, and REM apnea of 10 seconds or longer decreased from 27% at 40 weeks to 0% at 52 weeks. This suggests that semi-independent apnea turn-on and turn-off mechanism operate during REM sleep. A correlation between brief apneas and the longer apneas was seen only during REM sleep. For all sleep states, there was no correlation between the levels of apnea of 5 seconds or longer at 40, 44, and 52 weeks.

Aging↗
PubMedDate not supplied

Primary care physicians' practice patterns and diabetic retinopathy. Current levels of care.

BACKGROUND: Diabetic retinopathy is a costly and prevalent complication of diabetes mellitus. OBJECTIVE: To assess primary care physicians' self-reported practice patterns for the screening and detection of diabetic retinopathy relative to published guidelines. PARTICIPANTS AND METHODS: All primary care physicians (defined as general internists, family practitioners, and general practitioners) in Indiana were identified and surveyed using a mailed questionnaire. Of 2390 physicians, 1508 (63%) responded and were determined to be eligible. Of these 1508 physicians, 1058 (70%) completed all or some of the eye care-related questions. For each eye care practice, physicians were asked to specify the proportion of patients to which the practice was applied and the frequency (eg, every 3 months) with which the behavior was performed, if appropriate. Physicians were also asked to distinguish between patients with type I (insulin-dependent) and type II (non-insulin-dependent) diabetes mellitus for each practice behavior. RESULTS: Physicians' responses were classified as "high," "moderate," or "low" based on the American Diabetes Association guidelines. Forty-five percent of the physicians' responses were classified as high for referring all of their patients with type I diabetes mellitus to an eye care specialist annually as were 35% of the physicians' responses for referring their patients with type II diabetes mellitus. Fewer physicians reported high levels of routine in-office funduscopic examination. No relationship was found between the extent to which physicians performed an in-office funduscopic examination and patterns of referral to eye care specialists. Logistic regression analysis suggested that recent graduates and general internists are most likely to report behavior that is considered high (P < .05). CONCLUSION: The diabetic retinopathy-related practice patterns of primary care physicians in Indiana differ significantly from published guidelines.

Diabetes Mellitus, Type 1↗
PubMedDate not supplied

Epidermal growth factor accelerates recovery of LLC-PK1 cells following oxidant injury.

In renal tubular epithelial cells, oxidant injury results in several metabolic alterations including ATP depletion, decreased Na+K+ATPase activity, and altered intracellular sodium and potassium content. To investigate the recovery of LLC-PK1 cells following oxidant injury and to determine if recovery can be accelerated, we induced oxidant stress in LLC-PK1 cells with 500 microM hydrogen peroxide for 60 min. Identical cohorts of oxidant-stressed cells were incubated in recovery medium without epidermal growth factor (EGF) or recovery medium containing 25 ng EGF per ml. ATP levels, Na+K+ATPase activity in whole cells, Na+K+ATPase activity in disrupted cells, and intracellular sodium and potassium ion content were determined at 0, 5, 24, 48, and 72 h following oxidant injury in each cohort of cells. In oxidant-stressed cells recovering in medium without EGF, ATP levels, Na+K+ATPase activity, and intracellular ion content improved but continued to remain substantially lower than control values at all time points following oxidant stress. In cells recovering in medium with EGF, ATP levels, Na+K+ATPase activity, and the intracellular potassium-to-sodium ratio were significantly higher at nearly all time points than values in cells recovering in medium alone. In cells recovering with added EGF, Na+K+ATPase activity had improved to control levels, whereas ATP levels and intracellular ion content approached control values by 72 h following oxidant stress. We conclude that oxidant-mediated ATP depletion, altered Na+K+ATPase activity, and intracellular ion content remain depressed for several d following oxidant stress and that EGF accelerated recovery of LLC-PK1 cells from oxidant injury.

Adenosine Triphosphate↗