Biomedical subjects

J Belik

Publications and source records attributed to J Belik.

50 records · Page 3Linked to original sources

PubMed1989

Cerebral metabolic response and mitochondrial activity following insulin-induced hypoglycemia in newborn lambs.

We evaluated the newborn lamb's cerebral cellular activity and metabolism following acute insulin-induced hypoglycemia. Eleven animals received an insulin bolus followed by a continuous infusion to maintain a plasma glucose of 1 mM/l for 2 h, while 8 other animals received an equivalent dose of saline. Following the induction of hypoglycemia, the animals became quiet and transient seizures were observed in 3 animals. A significant increase in heart rate (p less than 0.01), and a decrease in arterial PaCO2 at 30 min (p less than 0.01), and pH at 2 h (p = 0.02), following hypoglycemia, were observed in the experimental group. Hypoglycemia did not significantly alter the cerebral blood flow, mitochondrial respiratory control ratio or the state-3 activity. The cerebral arteriovenous difference (CAVD) for oxygen did not change, while the glucose CAVD was significantly reduced from 0.47 +/- 0.21 to 0.24 +/- 0.16 mM/l (p less than 0.05) at the end of the hypoglycemia period, suggesting consumption of alternate substrates of energy by the brain. Insulin-induced hypoglycemia was associated with a significant increase in arterial lactate (p less than 0.01), and a significant correlation (p less than 0.01) between arterial and CAVD for lactate and beta-hydroxybutyrate (BOB) was observed. Cerebral consumption of alternate substrates of energy was inconsistent, and only observed for lactate in 5 and for BOB in 3 experimental animals following hypoglycemia. These data indicate that the newborn lamb's cerebral cellular activity is not affected by the degree of hypoglycemia achieved in these studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Central hemodynamic and regional blood flow changes in the newborn with right ventricular hypertension.

To evaluate the central hemodynamic and regional blood flow changes associated with right ventricular hypertension in the newborn, 13 anesthetized, mechanically ventilated piglets less than 3 d old were acutely instrumented to permit measurements of central vascular pressures, cardiac output, and regional blood flow (radio-labeled microsphere technique). After initial measurements, right ventricular afterload was progressively increased by means of a pulmonary arterial mechanical occluder until right-to-left foramen ovale shunt was observed. An increase in pulmonary arterial pressure from 32 +/- 2 to 55 +/- 3 mm Hg was associated with a decrease in PaO2 from 364 +/- 16 to 88 +/- 9 mm Hg and an increase in the shunt fraction from 13 +/- 1 to 28 +/- 1% (p less than 0.01) during ventilation with oxygen. Right ventricular hypertension induced a significant decrease in systemic arterial pressure from 79 +/- 3 to 63 +/- 4 mm Hg, and left ventricular cardiac output from 156 +/- 10 to 112 +/- 11 mL.min-1.kg-1 (p less than 0.01), likely secondary to a reduction in left ventricular compliance. Oxygen delivery to the brain and heart were unaffected, due to a substantial increase in regional blood flow, but a significant reduction in delivery to the bowel and kidneys were observed. Contrary to what has been reported in the adult, myocardial blood flow to the right ventricle increased during hypertension. Metabolic acidosis was seen in all animals and the changes in serum bicarbonate and whole body oxygen consumption were directly related to the magnitude of decline in systemic O2 delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Thoracic electric bioimpedance measurement of cardiac output in the newborn infant.

To evaluate thoracic electric bioimpedance as a noninvasive method for measuring cardiac output, we compared the bioimpedance measurements with those obtained by means of the thermodilution indicator cardiac output technique in seven preterm and term lambs; we also studied 17 term and preterm infants. Sixty-seven simultaneous bioimpedance and thermodilution cardiac output measurements were obtained in the animals after intravascular volume expansion (saline solution infusion) and contraction (phlebotomy). A significant correlation between the cardiac output measurements by the two methods (0.82; p less than 0.001) was observed. In neonates, the observed cardiac output was 198 +/- 46 ml/kg.min in the preterm infants and 178 +/- 46 ml/kg.min in the term infants. Extrapolating animal data to the neonates, we found the thoracic segment length recommended (the average of 29% of body length and electrode distance) to be accurate. These data indicate that bioimpedance cardiac output measurement (1) is comparable to measurement by the thermodilution indicator technique in the newborn animal and (2) may be suitable for use in infants and children.

Animals↗

PubMed1988

Blood-brain barrier to hydrogen ion during acute metabolic acidosis in piglets.

The present study investigates the integrity of the blood-brain barrier to H+ or HCO3- during acute plasma acidosis in 35 newborn piglets anesthetized with pentobarbital sodium. Cerebrospinal fluid acid-base balance, cerebral blood flow (CBF), and cerebral oxygenation were measured after infusion of HCl (0.6 N, 0.191-0.388 ml/min) for a period of 1 h at a constant arterial PCO2 of 35-40 Torr. HCl infusion resulted in decreased arterial pH from 7.38 +/- 0.01 to 7.00 +/- 0.02 (P less than 0.01). CBF measured by the tracer microsphere technique was decreased by 12% from 69 +/- 6 to 61 +/- 4 ml.min-1.100 g-1 (P less than 0.05). Infusion of 0.6 N NaCl as a hypertonic control had no effect on CBF. Cerebral metabolic rate for O2 and O2 extraction was not significantly changed from control (3.83 +/- 0.20 ml.min-1.100 g-1 and 5.7 +/- 0.6 ml/100 ml, respectively) during acid infusion. Cerebral venous PO2 was increased from 41.6 +/- 2.1 to 53.8 +/- 4.0 Torr by HCl infusion (P less than 0.02) associated with a shift in O2-hemoglobin affinity of blood in vivo from 38 +/- 2 to 50 +/- 1 Torr. Cisternal cerebrospinal fluid pH decreased from 7.336 +/- 0.014 to 7.226 +/- 0.027 (P less than 0.005), but cerebrospinal fluid HCO3- concentration was not changed from control (25.4 +/- 1.0 meq/l). These data suggest that there is a functional blood-brain barrier in newborn piglets, that is relatively impermeable to HCO3- or H+ and maintains cerebral perivascular pH constant in the face of acute severe arterial acidosis. (ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗

PubMed1988

Hyperventilation in the newborn piglet does not increase whole body oxygen consumption as seen in mature animals.

Hyperventilation has been shown to cause increased whole body oxygen consumption (VO2) and lactic acid production in human and animal mature subjects, but limited data are available in neonates. We investigated the effect of hypocarbic and normocarbic hyperventilation during normoxia and hypoxia (fractional inspired oxygen concentration = 0.14) upon the VO2 in anesthetized and paralyzed piglets. Systemic arterial, pulmonary arterial, and left and right atrial pressures as well as cardiac output and body temperature were continuously recorded. Hypocarbic hyperventilation (PaCO2 = 19 +/- 1 mm Hg; pH = 7.58 +/- 0.02) was associated with a significant decrease in systemic and pulmonary arterial pressures and cardiac output. These measurements returned to values similar to the initial normoventilation ones when PaCO2 was increased by adding CO2 to the inspired gas, whereas hyperventilation was continued. Neither hyperventilation alone nor in combination with hypoxia induced any significant change in VO2. We conclude that in the newborn pig, unlike what has been reported in mature subjects, cellular metabolic function is unaffected by hyperventilation as evidenced by the unchanged VO2.

Animals↗

PubMed1987

Metatropic dwarfism. Uncoupling of endochondral and perichondral growth.

Metatropic dwarfism is a rare heritable skeletal dysplasia that is thought to result from a defect in endochondral ossification. Histological studies have been few and have yielded inconsistent findings. In addition, no investigator has commented on the structure and function of the perichondral portion of the growth plate in patients who have metatropic dysplasia. To further characterize this disturbance, histological studies were carried out on autopsy specimens from the proximal part of the femur and the iliac crest of a patient who had this disorder. The major findings were: the absence of formation of normal primary spongiosa in the metaphysis; the presence of a thin seal of bone at the chondro-osseous junction, with abnormal metaphyseal vascular invasion and arrest of endochondral growth; and normal-appearing perichondral ring structures with persistence of circumferential growth. These findings suggest an uncoupling of endochondral and perichondral growth and offer an explanation for the dumbbell-shaped morphological structure of the osseous metaphysis that is seen in patients who have metatropic dysplasia. Other observations included prominence of the cartilaginous canals and vascular channels in the reserve zone; clumping of chondrocytes with enhanced staining of the pericellular matrix in the proliferative zone; a decreased ratio of cells to matrix in the hypertrophic zone, with intracellular metachromatic granules and incomplete evolution of chondrocytes; complete absence of an alcian-blue-positive zone of provisional calcification; and, finally, islands of dysplastic chondrocytes in the metaphysis. These abnormalities suggest that metatropic dysplasia is not simply a disorder of endochondral ossification. There appear to be associated defects in the longitudinal proliferation and maturation of chondrocytes and in the production of normal matrix.

Achondroplasia↗

PubMed1985

Respiratory complications of metatropic dwarfism.

Two infants with clinical and radiologic features of metatropic dwarfism presented in the neonatal period with episodes of cyanosis. Diagnostic studies to determine the etiology of these spells, including electrocardiogram, electroencephalogram, arterial blood gases, and metabolic and sepsis studies, were unremarkable. Chest roentgenograms revealed the characteristic long, narrow thoracic cage with no evidence of parenchymal disease. Cervical spine stability evaluation, pulmonary function studies, and chest impedance monitoring with qualitative air flow thermistor studies and transcutaneous oxygen monitoring were carried out. Both patients demonstrated a significant increase in resistance of the respiratory system following passive maneuvering of the head from a neutral position, suggestive of hypopharyngeal air flow obstruction. Obstructive sleep apnea resulting in cyanosis was documented in both patients. All other studies failed to yield a cause for the episodes of cyanosis. Our investigation failed to alter the clinical course which resulted in respiratory arrest and death by 7 months of age. A table is presented for the differentiation of skeletal dysplasias presenting in the perinatal period.

Cervical Vertebrae↗

PubMed1984

Chylothorax--a complication of chest tube placement in a neonate.

A premature infant with respiratory distress syndrome developed a left chylothorax after evacuation of a left tension pneumothorax. The Argyle catheter noted in the posterosuperior mediastinum possibly traumatized the thoracic duct. Although the infant's chylothorax resolved with conservative management, he subsequently died of severe bronchopulmonary dysplasia. The potential complication of chylothorax from thoracostomy tubes can be prevented by avoiding penetration into the posterosuperior mediastinum.

Chylothorax↗

PubMed1984

Cerebral blood flow and metabolism following pancuronium bromide in newborn lambs.

The purpose of this study was to evaluate cerebral blood flow and metabolism following pancuronium bromide paralysis in healthy newborn lambs. Cerebral blood flow and cerebral metabolic rate for O2 and glucose were measured along with blood pressure and blood gases before and again at 15 and 60 min following pancuronium paralysis in seven newborn lambs. Pancuronium bromide paralysis had no effect on any of these parameters either at 15 or 60 min of paralysis. Total cerebral blood flow, cerebral metabolic rate for O2, and cerebral metabolic rate for glucose were 87 +/- 6 ml/min/100 g, 258 +/- 10 mumol O2/min/100 g, and 53 +/- 10 mmol glucose/min/100 g, respectively. Neither was any change in regional cerebral blood flow noted. In spite of being connected immediately to the ventilator, however, some animals experienced a transient increase (average = 32%) in blood pressure, that was not associated with an increase in end tidal CO2. The data suggest that pancuronium paralysis in healthy awake newborn lambs does not lead to any alteration in cerebral blood flow or metabolism.

Animals↗

PubMed1983

Elevated amylase levels as a result of self-induced hypersalivation.

A patient with recurrent vomiting, abdominal pain, and elevated serum amylase activity may have pancreatitis. Although elevated serum amylase levels are a sensitive indicator for acute pancreatitis, this test is not highly specific for pancreatic disease. A patient is described who illustrates the need for specific laboratory, historical, and occasional psychological evaluation in pediatric patients with elevated amylase values.

Abdomen↗

PubMed1982

Changes in pulmonary function during the diuretic phase of respiratory distress syndrome.

To evaluate the relationship between improvement in pulmonary function and spontaneous diuresis in respiratory distress syndrome, nine premature infants requiring mechanical ventilation for RDS were studied at a mean age of 11.9 hours prior to the onset of diuresis, at onset of diuresis, at maximum urine output (mean age 44.9 hours), and at 24 hours after maximum urine output. Prior to diuresis functional residual capacity decreased from mean +/- SEM of 16.2 +/- 2 to 13.3 +/- 1.2 ml/kg, and dynamic lung compliance decreased from 2.5 +/- 0.3 to 1.8 +/- 0.3 ml/cm H2O (P less than 0.05), indicating that the respiratory disease was worsening. There was no significant change in alveolar-arterial oxygen gradient, peak inflating pressure, or rate of intermittent mandatory ventilation over this period. At the time of maximum urine output, however, FRC had increased 36% (P less than 0.05). CL had increased by 60% to 2.8 +/- 0.4 ml/cm H2O (P less than 0.025), AaDO2 had decreased from 246 +/- 27 to 184 +/- 30 torr (P less than 0.005), and PIP had decreased from 14.9 +/- 2.2 to 11.3 +/- 2.1 cm/H2O (P less than 0.05). On follow-up study 24 hours after maximum urine output, there was no further significant improvement in FRC, CL or PIP, but IMV rate and AaDO2 continued to decrease. These data show that the pulmonary function in RDS deteriorates until the onset of diuresis, after which it rapidly improves. This diuresis may represent the removal of excess lung liquid and seems necessary for improvement in RDS.

Diuresis↗

PubMed1980

Successful management of bacterial endocarditis of the mitral valve due to Staphylococcus epidermidis in an immunosuppressed host.

We report the successful management of bacterial endocarditis of the mitral valve, caused by Staphylococcus epidermidis, in a 34-month-old boy with acute lymphocytic leukemia who had been receiving immunosuppressive therapy. M-mode echocardiography provided early detection of valvular vegetations and documented the evolution of valvular involvement during the course of the illness.

Anti-Bacterial Agents↗

PubMedDate not supplied

Effect of early furosemide administration in neonates with respiratory distress syndrome.

The effect of early furosemide-induced diuresis was prospectively evaluated in 39 neonates less than 24 hr of age with clinical respiratory distress syndrome (RDS) who received either four doses of furosemide (1 mg/kg) or no diuretic. Measurements of FiO2 alveolar-arterial oxygen gradient (P[A-a]O2), peak inspiratory pressure (PIP), and urine output as a fraction of intake (O/I) were averaged for every 8 hr. The furosemide group overall showed a significant decrease (P less than 0.01) in FiO2, P[A-a]O2, and PIP with an earlier (32 hr vs 52 hr) and more pronounced diuresis (35% greater O/I) when compared to the controls. This effect was accentuated in the subgroup with 1,000-1,500 g birth weight (significantly lower FiO2 and P(A-a)O2 from 16 to 48 hours), while no increase in urine output was observed for the infants weighing less than 1,000 g. A significant reduction in supplemental oxygen and need for ventilatory support at 96 hr of age was observed in the furosemide-treated, less than 1,500-g infants. The incidence of patent ductus arteriosus was not increased following furosemide therapy, and no significant difference in echocardiographic parameters was observed in 21 infants from both groups, who were followed daily during the first week of life. This study suggests that early furosemide-induced diuresis, particularly in infants weighing 1,000-1,500 g at birth, promotes improvement in pulmonary functions in RDS and leads to faster reduction in oxygen and ventilatory support.

Birth Weight↗

PubMedDate not supplied

Association of maternal lithium exposure and premature delivery.

Lithium is widely used and the treatment of choice for patients with manic-depressive illness. For pregnant patients with manic-depressive illness, however, the use of lithium during the first trimester of pregnancy may present an increased risk for fetal maldevelopment. We have recently cared for several large-for-gestational-age, prematurely born infants whose mothers were treated with lithium throughout pregnancy. To determine whether maternal lithium use during pregnancy may predispose to the onset of premature labor and fetal macrosomia, we reviewed records from the International Register of Lithium Babies and from a cohort of manic-depressive pregnant women. More than one third (36%) of infants reported to the International Register were born prematurely, and 37% of the premature infants were large for gestational age; 15% of the term infants were born large for gestational age. In the cohort group, manic-depressive mothers who received lithium during pregnancy had a 2.5-fold higher incidence of premature births than manic-depressive pregnant patients who did not receive lithium treatment. The incidence of large-for-gestational-age births in lithium-treated women in the cohort was not different from that of the general population or from manic-depressive women not treated with lithium. In summary, an association between maternal lithium therapy and premature delivery is reported. We recommend that women receiving lithium therapy during pregnancy be closely monitored for the onset of premature labor.

Adult↗