Pneumocystis pneumonia in brain tumor patients: risk factors and clinical features

We reviewed the clinical features and risk factors for Pneumocystis carinii pneumonia (PCP) in patients with brain tumors (BTs) seen at our institution between 1980 and 1992. Previously rare, this opportunistic infection appears to be increasing among HIV-negative cancer patients receiving immunosuppressive medications. Recent reports have noted PCP among BT patients receiving corticosteroids, and suggested that these patients are particularly likely to develop PCP when corticosteroids are tapered. Nine BT patients, eight with high-grade gliomas, experienced ten episodes of PCP. None were known HIV-positive. All were on dexamethasone (DXM) at PCP onset, and had continuously been receiving it for 47-398 days (median 69). Daily DXM dose at PCP onset ranged from 1-16 mg (median 9). Five episodes occurred in patients receiving a stable DXM dose and five during DXM taper. Nine episodes occurred in patients receiving chemotherapy. All patients had absolute lymphopenia at PCP onset, ranging from 80-900 x 10(6) lymphocytes/l (median 222 x 10(6)/l, normal > 1000 x 10(6). Three episodes were fatal despite appropriate antibiotic therapy. Unlike others, we did not find that corticosteroid taper predisposed to developing PCP. As in HIV, PCP in BT patients appears related to lymphopenia, in these patients attributable to use and duration of corticosteroids and in some cases cytotoxic chemotherapy. Effective prophylaxis exists and should be considered for lymphopenic patients and those requiring DXM for > five weeks.

Uncommon brain tumors

The widespread availability of neuroimaging tests and the increasing use of stereotactic biopsy or surgical resection to obtain a histologic diagnosis have resulted in more patients with uncommon brain tumors coming to the attention of doctors. This article reviews the presentation and management of some of the less common brain tumors in adults. These include pineal tumors, medulloblastomas, ependymomas, choroid plexus tumors, ganglion cell tumors, neurocytomas, dysembryoplastic neuroepithelial tumors, esthesioneuroblastomas, Lhermitte-Duclos disease, hemangioblastomas, chordomas, and cystic lesions.

Independent efferent populations in the nucleus of the optic tract: an anatomical and physiological study in rat and cat

The efferent projections of the nucleus of the optic tract (NOT) and dorsal terminal nucleus of the accessory optic system (DTN) to the contralateral NOT-DTN, ipsilateral inferior olive (IO), ipsilateral nucleus prepositus hypoglossi (NPH), and ipsilateral dorsal lateral geniculate nucleus (LGNd) were examined in pigmented rats and in cats by using anterograde and retrograde tract tracing, as well as extracellular recording and electrical stimulation. Anterograde tracing in the rat revealed a dense termination field of NOT-DTN efferents throughout the homologous contralateral territory. In both species three different cell populations, projecting to the contralateral NOT-DTN, ipsilateral IO, and ipsilateral LGNd, respectively, were distinguished by means of multiple retrograde tracing. No clear topographical segregation of the different NOT-DTN relay cell populations was observed. On the other hand, a large proportion (at least 60%) of NOT-DTN neurons projecting to the ipsilateral NPH were found to bifurcate upon the IO in the rat. Electrophysiologically, NOT-DTN neurons projecting to the IO were identified by their directionally selective responses. Such neurons were never activated by electrical stimulation of either the contralateral NOT-DTN or the ipsilateral LGNd. Neurons antidromically activated from the contralateral NOT-DTN could not be activated from the ipsilateral LGNd. Thus, in both cat and rat the NOT-DTN includes at least three independent relay cell populations. As a consequence, the NOT-DTN must serve functions additional to the generation of eye movements during optokinetic nystagnus, a function subserved by the directionally selective NOT-DTN cells.

Effects of two rescue doses of synthetic surfactant in 344 infants with respiratory distress syndrome weighing 750 to 1249 grams: a double-blind, placebo-controlled multicenter Canadian trial. Canadian Exosurf Neonatal Study Group

In a multicenter, double-blind, placebo-controlled rescue trial conducted at 13 Canadian hospitals, two 5 ml/kg doses of a synthetic surfactant or air placebo were administered to 344 infants with birth weights of 750 to 1249 gm who had established respiratory distress syndrome and an arterial/alveolar oxygen tension ratio less than 0.22. The first dose was given between 2 and 24 hours of age, and the second dose was given 12 hours later to the infants remaining on mechanical ventilation. Infants were stratified at study entry by birth weight and gender. The trial was terminated short of the targeted sample size because significant reductions in mortality were observed in another rescue trial completed in the United States in the same weight class of infants. Despite premature termination of the trial, the rate of survival without bronchopulmonary dysplasia was increased (61% vs 52%; p = 0.046) in infants treated with surfactant. In addition, there was a significant reduction in the incidence of overall pulmonary air leak (46% vs 32%; p = 0.009), pneumothorax (27% vs 17%; p = 0.023), and pulmonary interstitial emphysema (40% vs 28%; p = 0.018) in infants treated with synthetic surfactant. There was no difference in the incidence of bronchopulmonary dysplasia, apnea, or pulmonary hemorrhage. Significant improvements in alveolar-arterial oxygen tension gradient, arterial/alveolar oxygen tension ratio, and oxygen and ventilator requirements through day 7 were present. These findings indicate that rescue therapy with synthetic surfactant can improve outcome for premature infants weighing 750 to 1249 gm with respiratory distress syndrome.

Outcome after spinal reirradiation for malignant epidural spinal cord compression

Radiotherapy is effective for most cases of spinal cord compression. Although recurrent spinal cord compression is a common problem, little is known about whether reirradiation preserves neurologic function and what risk of radiation myelopathy it carries. To investigate this question, we reviewed patients at the Mayo Clinic between 1975 and 1992 undergoing two or more courses of radiotherapy to the same segment of the spinal column with radiographically documented epidural disease at the time of reirradiation to determine outcome as measured by the ability to walk and by survival. Fifty-four patients met the study criteria. Radiation doses for the first course ranged from 2,250 to 5,400 cGy (median, 3,000 cGy), and total dose for all courses to the reirradiated spinal segment ranged from 3,650 to 8,089 cGy (median, 5,425 cGy). All patients were ambulatory following the first course of radiation, 40 (74%) were ambulatory at the onset of reirradiation, and 42 (78%) were ambulatory at the end of reirradiation. Thirty-seven patients (69%) remained ambulatory at their last follow-up 6 days to 80 months following reirradiation (median, 4.7 months). Five patients eventually became nonambulatory 6.5 to 35 months following reirradiation. Median survival for all patients following reirradiation was 4.2 months. We conclude that for cancer patients with progressive epidural disease following radiotherapy, reirradiation frequently preserves ambulation and carries minimal risk of radiation myelopathy during the patients' lifetime.

Therapy of venous thromboembolism in patients with brain metastases

BACKGROUND

Deep venous thrombosis (DVT) and pulmonary embolism (PE) are common in patients with brain metastases. Few data exist to help guide the clinician's choice between the two therapeutic options of anticoagulation and inferior vena cava filter placement.

METHODS

The authors reviewed their institutions' experience with the treatment of venous thromboembolism in 51 adult patients with known brain metastases since 1980.

RESULTS

Ten patients were initially treated with Greenfield filters; four (40%) had recurrent nonfatal thromboembolic events (two PE and two DVT), and three required anticoagulation. Thirty-nine patients were treated initially with anticoagulation; none of these patients later received filters. Two patients with DVT were untreated and both died of PE. Among 42 patients who received anticoagulation, the duration of anticoagulation ranged from 5 to 563 days (mean, 100 days). Two patients who received anticoagulation experienced devastating central nervous system hemorrhage in the setting of supratherapeutic anticoagulation by conventional laboratory criteria. A third patient experienced a minor deterioration, possibly attributable to hemorrhage, for a 7% (3 of 42) incidence of serious central nervous system complications. Three asymptomatic patients developed hyperdensity within metastases on routine follow-up noncontrast computed tomography scan, suggesting possible intratumoral hemorrhage. Three patients taking warfarin had recurrent DVT with prothrombin time between 15.1 and 17.7. Systemic bleeding complications were generally minor and occurred in only eight patients (19%).

CONCLUSIONS

Anticoagulation is more effective than Greenfield filters and acceptably safe when maintained in the therapeutic range in most patients with brain metastases and venous thromboembolism.

Complications of therapy for venous thromboembolic disease in patients with brain tumors

Venous thromboembolic disease is a frequent complication in patients with intracranial malignancies. Because these patients are often perceived to be at increased risk of intracranial hemorrhage with anticoagulation, inferior vena cava (IVC) filters are frequently used in their treatment. We reviewed the records of 49 patients with intracranial malignancies and venous thromboembolic disease to determine the effectiveness of, and the complications resulting from, treatment. Of the 42 patients receiving IVC filters, a strikingly high percentage (62%) developed complications. Twelve percent developed recurrent pulmonary embolism, while 57% developed either IVC or filter thrombosis, recurrent deep venous thrombosis, or post-phlebitic syndrome. These complications severely reduced the quality of life of the affected patients. Only 15 of our patients were treated with anticoagulation, and seven of these received it because of continued thromboembolic disease. None of these 15 patients had proven hemorrhagic complications. This study suggests that the complication rate of IVC filters in patients with brain tumors is higher than commonly perceived and may outweigh the risk of anticoagulation.

Deceptively normal ventricular fluid in lymphomatous meningitis

The diagnosis of leptomeningeal cancer ultimately depends on the finding of abnormal cerebrospinal fluid with malignant cytologic study results. We report a case of relapsed leptomeningeal lymphomatosis in which ventricular cerebrospinal fluid was entirely normal while lumbar spinal fluid was diagnostically abnormal. To our knowledge, this is the first such reported case, and it highlights the importance of sampling cerebrospinal fluid close to the site of clinical involvement.

Retrospective search for bleeding diathesis among premature newborn infants with pulmonary hemorrhage after synthetic surfactant treatment. The American Exosurf Neonatal Study Group I, and the Canadian Exosurf Neonatal Study Group

In an across study analysis of five multicenter, placebo-controlled trials of the synthetic surfactant, Exosurf Neonatal, involving infants with birth weights 700 gm or greater the incidence of clinical pulmonary hemorrhage was 1.9% in treated infants and 1.0% in control infants. To determine whether this apparent increase in pulmonary hemorrhage was the result of a bleeding diathesis, we retrospectively reviewed charts for 39 of 41 infants with clinical pulmonary hemorrhage. The incidence of nonpulmonary bleeding was the same in control- and surfactant-treated infants. Platelet counts, hematocrit values, and the number of transfusions with platelets or red blood cells did not differ between the two groups. There was no evidence that surfactant treatment was specifically associated with a generalized bleeding diathesis.

Neonatal jaundice and bilirubin encephalopathy: a clinical and experimental reappraisal

Hyperbilirubinemia and bilirubin encephalopathy are well-known occurrences in the neonatal period. The fact that bilirubin might be toxic to neural cells stems from the neurological picture that has emerged and the associated hyperbilirubinemia. Studies of the relationship between hyperbilirubinemia in healthy full-term infants and the long-term consequences showed little or no effect of bilirubin. Nevertheless, bilirubin is still considered toxic to premature infants and infants with hemolysis. In addition, in spite of a fairly detailed understanding of the chemistry of bilirubin and the biochemistry of bilirubin metabolism, the primary target of its toxic effect is still not known. The difficulties in analyzing the results are due to the variation in experimental designs, the use of different animal models and cell systems and the use of unstable bilirubin solutions. We review some of the problems related to clinical and experimental studies of bilirubin toxicity.

The Koch pouch: radiographic evaluation of the orthotopic and cutaneous forms

The Koch pouch is a continent ileal reservoir. It has several advantages over the standard ileal conduit. The pouch can be attached to the skin (cutaneous type) or the male urethra (orthotopic type). Both variations have special imaging considerations. The suggested imaging protocol is based upon experience with 47 patients (22 with orthotopic and 25 with cutaneous pouches). The normal appearance of the new and mature pouch and its complications and their management are presented.

Monochorionic diamniotic minimally conjoined twins: a case report

We present the second case of monochorionic diamniotic (MC/DA) conjoined twins. There was minimal conjunction, which was predominantly extrafetal and confined to the periumbilical ventral region. The omphalopagus twins, attached to a single forked umbilical cord, were connected by a shared umbilical hernia containing the ileum of twin B. The only visceral conjunction, located just within the belly of twin A, was midileal with the 2 separate ileums converging toward a short segment of shared muscularis propria and of side-to-side fistulization. Gastrointestinal and musculoskeletal anomalies were present in both twins with severe amyoplasia and arthrogryposis multiplex in twin A. Possible mechanisms underlying this unusual form of MZ twinning are discussed.

Bilirubin-neural cell interaction: characterization of initial cell surface binding leading to toxicity in the neuroblastoma cell line N-115

The toxicity of bilirubin to the nervous system might be due to its effect on several key enzyme reactions occurring in the intracellular compartment as suggested by in vitro studies. The question of how bilirubin, a molecule with poor solubility in water and organic solvents, interacts with the plasma membrane and reaches intracellular targets is unclear. In an attempt to get some insight into this problem, we have measured the uptake of bilirubin from bilirubin-albumin solutions by the murine neuroblastoma cell line N-115. At a constant total concentration of bilirubin, the initial rate, as well as the extent of uptake, increases with increasing bilirubin to albumin molar ratio (B/A). The binding is reversible, at least partially, as indicated by the ability of albumin to extract cell-bound bilirubin. The cellular uptake of bilirubin was found to depend also on the concentration of bilirubin, on temperature and on pH. The results are not consistent with either a carrier-mediated transport or passive diffusion across the plasma membrane. The data, however, seem to fit a multistep binding of bilirubin to the plasma membrane proposed for the interaction of bilirubin with synaptosomal plasma membrane vesicles, erythrocyte ghosts and lipid vesicles. These studies, thus, reveal the complexity of the binding interaction at the level of the plasma membrane and leave open the question of transport across the membrane.

Effects of lesions of the nucleus of the optic tract on optokinetic nystagmus and after-nystagmus in the monkey

1. The nucleus of the optic tract (NOT) and the dorsal terminal nucleus (DTN) of the accessory optic system were lesioned electrolytically or with kainic acid in rhesus monkeys. When lesions involved NOT and DTN, peak velocities of optokinetic nystagmus (OKN) with slow phases toward the side of the lesion were reduced, and optokinetic after-nystagmus (OKAN) was reduced or abolished. The jump in slow phase eye velocity at the onset of OKN was smaller in most animals, but was not lost. Initially, there was spontaneous nystagmus with contralateral slow phases. OKN and OKAN with contralateral slow phases were unaffected. 2. Damage to adjacent regions had no effect on OKN or OKAN with two exceptions: 1. A vascular lesion in the MRF, medial to NOT and adjacent to the central gray matter, caused a transient loss of the initial jump in OKN. The slow rise in slow phase velocity was prolonged, but the gain of OKAN was unaffected. There was no effect after a kainic acid lesion in this region in another animal. 2. Lesions of the fiber tract in the pulvinar that inputs to the brachium of the superior colliculus caused a transient reduction in the buildup and peak velocity of OKN and OKAN. 3. In terms of a previous model (Cohen et al. 1977; Waespe et al. 1983), the findings suggest that the indirect pathway that activates the velocity storage integrator in the vestibular system to produce the slow rise in ipsilateral OKN and OKAN, lies in NOT and DTN. Activity for the rapid rise in OKN, carried in the direct pathway, is probably transmitted to the pontine nuclei and flocculus via an anatomically separate fiber pathway that lies in the MRF. A fiber tract in the pulvinar that inputs to the brachium of the superior colliculus appears to carry activity related to retinal slip from the visual cortex to NOT and DTN.

Bilirubin toxicity in a neuroblastoma cell line N-115: II. Delayed effects and recovery

Clinical studies have suggested that the early stages of bilirubin encephalopathy are reversible. These phenomena are investigated at the cellular level using the neuroblastoma cell line N-115 as a model system. To determine whether the cell line N-115 can recover from bilirubin toxicity, and whether the cellular function remains intact after a short period of bilirubin exposure during which time no toxic effects are manifest, the cells are exposed to bilirubin at varying concentrations and varying bilirubin:albumin ratios for 1 and 2 h. The bilirubin is then washed out, and the cells are reincubated in fresh media with appropriate amounts of albumin. Mitochondrial function, [3H]thymidine uptake and L-[35S]methionine uptake are assessed at 2, 8, and 24 h of reincubation after the bilirubin washout. After the short-term exposure, the cells begin to demonstrate evidence of toxicity in all parameters measured 8-24 h after the bilirubin washout. After the 2-h exposure to bilirubin, the cells demonstrate significant toxicity within 2 h of the bilirubin washout. The degree of toxicity seems to depend on the bilirubin:albumin ratio and bilirubin concentration. In general, after bilirubin exposure of 1 h or longer, the N-115 cells develop evidence of toxicity which is progressive and irreversible.

Bilirubin toxicity in a neuroblastoma cell line N-115: I. Effects on Na+K+ ATPase, [3H]-thymidine uptake, L-[35S]-methionine incorporation, and mitochondrial function

Though bilirubin is reported to affect a variety of cellular functions, the primary target of its toxic effect is still not known. A major problem in understanding this is the wide variation in results reported by different groups. This is probably due to the differences in stability of bilirubin solutions arising from large differences in bilirubin:albumin molar ratios used in experiments. Hence in studying the toxic effects of bilirubin in tissue culture systems, it is important to be certain that the bilirubin is maintained in solution throughout the time of the exposure to bilirubin. Spectrophotometric measurements have shown that bilirubin is stable in Dulbecco's modified Eagle medium solution at bilirubin:albumin molar ratios up to 3. Under these defined conditions, bilirubin was found to affect Na+K+ ATPase, [3H]-thymidine uptake, L-[35S]methionine incorporation into protein and mitochondrial function at bilirubin concentrations up to 125 microM and bilirubin:albumin molar ratio of 1.5. Toxic effects on all parameters measured were evident at bilirubin:albumin molar ratio of 1.5 after a minimum of 2 h of exposure. No effect was evident at a bilirubin:albumin molar ratio below 1. Although it is not possible to identify with certainty the primary target, the effect on mitochondrial function appeared earlier and was more profound than that seen with the other assessed functions.

Nystagmus induced by stimulation of the nucleus of the optic tract in the monkey

1. The nucleus of the optic tract (NOT) was electrically stimulated in alert rhesus monkeys. In darkness stimulation evoked horizontal nystagmus with ipsilateral slow phases, followed by after-nystagmus in the same direction. The rising time course of the slow phase velocity was similar to the slow rise in optokinetic nystagmus (OKN) and to the charge time of optokinetic after-nystagmus (OKAN). The maximum velocity of the steady state nystagmus was approximately the same as that of OKAN, and the falling time course of the after-nystagmus paralleled OKAN. 2. Increases in frequency and duration of stimulation caused the rising and falling time constants of the nystagmus and after-nystagmus to become shorter. Changes in the falling time constant of the after-nystagmus were similar to changes in the time constant of OKAN produced by increases in the velocity or duration of optokinetic stimulation. 3. Stimulus-induced nystagmus was combined with OKN, OKAN and per- and post-rotatory nystagmus. The slow component of OKN as well as OKAN could be prolonged or blocked by stimulation, leaving the rapid component of OKN unaffected. Activity induced by electrical stimulation could also sum with activity arising in the semicircular canals to reduce or abolish post-rotatory nystagmus. 4. Positive stimulus sites for inducing nystagmus were located in the posterolateral pretectum. This included portions of NOT that lie in and around the brachium of the superior colliculus and adjacent regions of the dorsal terminal nucleus (DTN). 5. The data indicate that NOT stimulation had elicited the component of OKN which is responsible for the slow rise in slow phase velocity and for OKAN. The functional implication is that NOT, and possibly DTN, are major sources of visual information related to retinal slip in the animal's yaw plane for semicircular canal-related neurons in the vestibular nuclei. Analyzed in terms of a model of OKN and OKAN (Cohen et al. 1977; Waespe et al. 1983), the indirect pathway, which excites the velocity storage mechanism in the vestibular system to produce the slow component of OKN and OKAN, lies in NOT in the monkey, as it probably also does in cat, rat and rabbit. Pathways carrying activity for the rapid rise in slow phase velocity during OKN or for ocular pursuit appear to lie outside NOT.

A description of the changing body composition of the growing premature infant

Data from studies of two similar groups of premature infants were used to describe the changing body composition (BC) of a "typical" premature infant, 3 to 4 weeks old, gaining weight from 1,200 to 2,000 g and being fed its mother's expressed breast milk at a metabolizable energy intake of 93.6 kcal/kg/day. Serial measurements had been made of total body water (TBW), the extracellular fluid space (ECF), nitrogen balance, and gross energy balance in one group of premature (n = 17) infants and of total body potassium (TBK) in another group (n = 23); all infants studied weighed between 900 and 2,300 g. Equations relating TBW, ECF, and TBK to body weight were derived for estimating the content of these substances at body weights between 1,200 and 2,000 g. Protein content at 1,200 g body weight was estimated from measured TBK and N:K ratio (determined from the reference fetus) at this weight. Subsequent protein content was determined from average N accretion, determined from data of N balance, and carbohydrate and ash content were estimated from reference data. The remainder of the body weight was assumed to be fat. At 1,200 g, the proposed BC of the premature infant is 72.1% water, 10.7% protein, 14.9% fat, 1.9% ash, and 0.4% carbohydrate. At 2,000 g comparable figures are 67.8% water, 11.6% protein, 18.2% fat, 1.9% ash, and 0.5% carbohydrate. The description also provides estimates of the body cell mass (BCM) and intracellular fluid (ICF), the relationship of K to the BCM and ICF, and the energy balance of the growing premature infant.

Bilirubin diffusion through lipid membranes

The possibility that bilirubin can diffuse through lipid bilayers is investigated with liposomes prepared from dipalmitoylphosphatidylcholine (DPPC), egg phosphatidylcholine (egg PC) with 22 mole percent cholesterol, and a lipid extract preparation from N115 neuroblastoma cells. Liposomes were prepared with internalized bilirubin and bovine or human serum albumin, and bilirubin efflux into an exogenous solution of human serum albumin was measured. Efflux from DPPC liposomes was significantly higher above the phase transition temperature than below it. This change was dependent on the lipid undergoing a phase transition and could not be accounted for by 6 K change in temperature. Maximum bilirubin efflux from egg PC-cholesterol liposomes was found to depend on the relative internal and external albumin pools, suggesting an equilibrium distribution of bilirubin between them. These observations demonstrate that bilirubin can diffuse freely through these lipid membranes.

Quantitative analysis of cerebral asymmetries. Fronto-occipital correlation, sexual dimorphism and association with handedness

To investigate the biological and functional significance of cerebral asymmetries, we measured lateral differences of the frontal and occipital poles on computed tomographic scans of 66 adult outpatients with no diagnosed abnormalities. In addition to confirming the greater average sizes of the right frontal and left occipital poles, we found a significant linear correlation relating anterior and posterior difference measures. Men showed greater degrees of frontal and occipital asymmetries than women; reversals of the typical asymmetries were more common among women. Reduction or reversal of the usual left occipital predominance in the presence of typical right frontal predominance was associated with non-right-handedness. These findings clarify and extend prior qualitative observations and relate to the possible role of testosterone in modulation of cortical asymmetries. Reduced structural asymmetries among women and non-right-handers may provide an anatomical basis for clinical and laboratory findings of lessened functional lateralization in these groups.

Bilirubin toxicity in neural cell lines N115 and NBR10A

The toxicity of bilirubin was investigated in 2 neural cell lines NBR10A and N115 using a quantitative dye assay 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium biomide (MTT) as a measure of cell viability and [3H]thymidine incorporation as a measure of DNA synthesis. Short exposures (up to 2 h) to bilirubin, even up to a bilirubin-albumin molar ratio of 1.5, yielded no evidence of toxicity using these assays. At longer exposure times (24 h) a decrease in cell viability and [3H]thymidine incorporation was detected at a molar ratio of 0.8 when the bilirubin concentration was 0.1 mM or higher, whereas lower bilirubin levels at this molar ratio showed no deleterious effect. The effect of bilirubin is more pronounced at a molar ratio of 1.5 with longer incubation periods. The MTT assay showed the N115 cells appeared to be more resistant to bilirubin cytotoxicity than NBR10A cells, a finding which was not obtained from [3H]thymidine incorporation studies. This discrepancy can be explained by the fact that we are measuring two different variables; the MTT assay estimates the number of viable cells at the end of the experiment by measuring mitochondrial function whereas the [3H]thymidine assay measures the rate of DNA synthesis during the last 2 h of the experiment. The concentration effect of bilirubin is evident from the [3H]-thymidine studies in that at a molar ratio of 1.5 and bilirubin concentration of 0.075 mM or higher, there is both cell kill (decrease in DNA) and inhibition of [3H]thymidine incorporation (decrease in specific activity).(ABSTRACT TRUNCATED AT 250 WORDS)

Total body digoxin clearance and steady-state concentrations in low birth weight infants

Serial serum digoxin concentrations were measured over a 10-day period in 15 low birth weight infants requiring digoxin therapy. The calculated total body digoxin clearance (TBDC) was found to be highly dependent on gestational age and body weight, with dose-normalized, steady-state digoxin concentrations inversely related to the same factors. Because of the decreased TBDC in low birth weight infants, our data support the recent recommendations in the literature to reduce maintenance doses of digoxin in these infants. Our study has further demonstrated that the reduction should be proportional to both gestational age and body weight.

Renal clearance of digoxin in premature neonates

The renal clearances of digoxin and creatinine were determined in seven premature neonates (mean gestational age = 29.9 wk, range = 26 to 36 wk) at a postnatal age of 1 to 9 days (mean = 4.1 days). The corrected renal digoxin clearance (mean, 10.4 ml/min/1.73 m2; range, 2.5 to 36.7) was highly dependent on gestational age and body weight, r being 0.95 and 0.96, respectively (exponential curve). The linear slope of corrected renal digoxin clearance vs. creatinine clearance plot approached unity (r = 0.99), indicating that digoxin and creatinine were handled similarly by the kidney in these premature neonates (i.e. glomerular filtration with some degree of tubular secretion). Our finding of slower renal digoxin clearance helps to explain the higher serum levels and longer half-life of this drug in premature neonates.

Clinical relevance of the plasma reserve albumin binding capacity for bilirubin (RABC) and "free" bilirubin concentration

An analysis of 55 plasma samples from 46 jaundiced newborn infants showed that endogenous "free" bilirubin levels bear no significant correlation to reserve albumin binding capacities for bilirubin as determined by both the Sephadex G-25 gel filtration and the enzymatic peroxidation technique (r = 0.14, p less than 0.05). This contrasts with the significant correlation between the "free" bilirubin concentrations and the bilirubin/albumin molar ratios in the same plasma samples (r = 0.75, p less than 0.001). The results of this study suggest that if "free" bilirubin is the "driving force" in the pathogenesis of bilirubin encephalopathy then the use of the reserve albumin binding capacity for bilirubin as the only guide in predicting the risk of kernicterus may not be adequate.

Angiotensin and drinking rates in the euryhaline killifish

Drinking rates were measured in the euryhaline fish Fundulus heteroclitus in the presence and absence of angiotensin II or its competitive inhibitor P-113 and converting enzyme inhibitor (SQ20881). Angiotensin stimulated drinking in Fundalus adapted to salt- or freshwater. More significant, P-113 decreased drinking rates in saltwater-adapted fish and to ones acutely exposed to saltwater. SQ20881 was also effective in inhibiting drinking. These data are interpreted to support the hypothesis that endogenously produced angiotensin is a physiological stimulus for drinking in fish.

The Meckel syndrome in the Hutterites

At least three cases of the Meckel syndrome have been identified in the Hutterites. Two of these were sibs and were studied during life; the other, a close relative, was diagnosed retrospectively by a review of hospital records. All parents were consanguineous. The phenotype ranged in severity from the association of occipital meningocele, cystic kidneys, postaxial polydactyly, and microphthalmia to a milder expression consisting of cystic kidneys, ocular defects apparent only on funduscopic examination, and a brain abnormality demonstrated by computer tomography. Survival ranged from 5 to 13 months. In one patient, the renal lesion was manifested as a tubular rather than a glomerular defect, and was probably not the primary cause of death.

Plasma carnitine levels during intravenous feeding of the neonate

The premature infant has a limited capacity for fatty acid oxidation. This study shows that solutions commonly used for intravenous feedings in the newborn infant contain no carnitine. Infants maintained on this solution have significantly lower total, free, and acylcarnitine levels as compared to when they are fed orally with expressed human milk or a proprietary formula, which is known to contain carnitine. The exogenous supply of carnitine to the premature infant may have a significant influence on the ability to stimulate optimal fatty acid oxidation.

Lipid metabolism in the neonate. III. The ketogenic effect of Intralipid infusion in the neonate

The ketogenic potential of Intralipid was studied in two groups of infants: 12 were SGA and 15 AGA; all were clinically stable and less than 48 hours of age. During four-hour Intralipid tolerance tests, the SGA infants achieved significantly higher plasma TG and FFA levels. Both groups of infants significantly increased the concentration of ketone bodies; however, there was no difference in the levels achieved. In view of the slower clearance rate of TG and the higher levels of FFA in SGA infants, it is speculated that in addition to a possible defective lipoprotein lipase system and a decrease in number and size of the adipose cells, beta-oxidation of FFA to ketones may be occurring at a slower rate. The generation of high levels of ketones during Intralipid infusion period in both groups of infants indicates that SGA infants can handle ketone bodies as readily as AGA infants.

Partial trisomy 12p due to t(12;21)pat translocation

Partial trisomy (interchromosomal duplication) of the short arm of chromosome No. 12 was observed in an infant girl with psychomotor retardation, prominent forehead, ptosis of the right eyelid, esotropia/exotropia, flat nose, hypotonia and other anomalies. A comparison of her features with those in five reported cases with a similar chromosomal imbalance shows certain features common to all, but the material is too limited for definitive characterization of a trisomy 12p syndrome.

Gentamicin and albumin-bilirubin binding. An in vivo study

Ten newborn infants were given gentamicin intramuscularly. Over a postinjection interval of 12 hours, no significant change occurred in the total binding capacity of serum albumin for bilirubin or in concentrations of serum bilirubin levels. There was no correlation between concentrations of serum gentamicin and the total binding capacity or serum bilirubin. This study provides in vivo data that supports recent in vitro experiments showing that gentamicin does not alter bilirubin-albumin binding.

Bilirubin quantitation with lipemic plasma

1. In the presence of lipemia, the estimation of BR by diazo method is variable and hence unreliable. 2. The estimation of BR in lipemic plasma by the use of the A-O bilirubinometer yielded BR levels which were consistently lower than theoretical values. 3. By regression analysis of the percent error in BR estimation, (using the A-O bilirubinometer) and TG Concentrations, a straight line is obtained. Based upon this line, a correction factor for plasma BR concentration in the range of 5-25 mg/dl can be obtained if the degree of lipemia is known.

Variance in albumin loading in exchange transfusions

To assess the rationale of albumin priming prior to exchange transfusions, 42 hyperbilirubinemic infants who required exchange transfusions were randomly assigned to one of two groups. Group I consisted of 15 infants who were given intravenously 1 gm/kg of salt-poor human serum albumin one hour before the exchanges. Group II, which consisted of 27 infants, received simple exchanges. No statistical differences were found in variations in reserve albumin-binding capacity, bilirubin, albumin, or red cell bilirubin at pre and one-hour post albumin infusion in the primed infants. The amount of bilirubin removed per kilogram is directly correlated to plasma bilirubin concentration (r=0.87). No significant difference in efficiency on bilirubin removal was seen between the two groups. Beneficial effects of albumin therapy was apparent only in those infants with low RABC as determined by the sephadex gel filtration technique.

Insulin responses during catch-up growth of infants who were small for gestational age

Growth characteristics of 15 full-term infants, selected because of weights more than 2 SD below the mean for gestational age, are described. The response to an intravenous injection of glucose was utilized to measure the insulin response of the infants at 6 months. Infants small for gestational age grow at a faster rate than appropriate-for-age infants during the first six months of life. There was a positive correlation between the growth velocity of the period and insulin release and a negative correlation between growth velocity and birth length. There was no correlation between these variables and increases in weight during the same period. Growth velocity during catch-up growth is related to the degree of preceding retardation but insulin may play a permissive role.

Lipid metabolism in the neonate. II. The effect of Intralipid on bilirubin binding in vitro and in vivo

The relationship between Intralipid fat emulsion and the binding of bilirubin to protein and cells was studied in vitro and in vivo. In the in vitro system, Intralipid had no beneficial effect in augmenting billirubin binding in adult whole blood. The unmetabolized Intralipid had no adverse effect on bilirubin binding in vitro. Twenty-seven neonates were infused with Intralipid (1 gm/kg) over a 4-hour period; the SGA infants achieved very high plasma concentrations of free fatty acids. When the molar ratio of free fatty acids to albumin in plasma was greater than six, the free fatty acids displaced bilirubin from albumin, resulting in the generation of free bilirubin. It is suggested that the molar ratios of free fatty acids to albumin in plasma be followed in any infant who is receiving Intralipid and that the dose of Intralipid be adjusted to maintain this ratio below six.

Lipid metabolism in the neonate. I. The effects of Intralipid infusion on plasma triglyceride and free fatty acid concentrations in the neonate

To determine the ability of the neonate to metabolize Intralipid, it was infused in a dose of 1 gm/kg of body weight over a 4-hour period to 27 infants in the first 48 hours of life. Differences in the metabolism of this lipid were related to gestational age and to weight for gestational age. Premature AGA infants of less than 33 week's gestation hydrolyzed the triglyceride to FFA more slowly than did AGA infants whose gestation was greater than 33 weeks. The SGA infants achieved very high plasma levels of triglycerides and free fatty acids during the infusion and cleared the lipid very slowly in the postinfusion period. This suggested impaired hydrolysis of the triglyceride and deficient uptake and/or utilization at a cellular level of the resulting free fatty acids in SGA infants.

Neonatal pneumopericardium

SUMMARY

Pneumopericardium developed in three newborn infants, including a set of twins, with respiratory distress syndrome. The rarity of this condition and its occurrence in two newborns suggest an anatomic predisposition, especially in premature infants requiring assisted ventilation. Two of the infants died; one had undergone pericardiocentesis. From a review of the literature and from our cases we conclude that conservative therapy appears warranted in cases of isolated pneumopericardium although the number of cases reported is too small to provide a definite answer.

Reye's syndrome in a newborn infant

A case of Reye's syndrome in a newborn infant, believed to be the first recorded in the perinatal period, is reported. The clinical, biochemical and histological findings are those previously recognized in older infants. The intractable acidosis, hypoglycemia and extreme degree of lactic acidosis reflect an advanced degree of hepatic involvement, probably initiated in utero, with resultant impairment of glycogenolysis and intermediary metabolism.