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PubMed1998

Assessment of neuroendocrine dysfunction following traumatic brain injury.

Posttraumatic neuroendocrine pathology may be a clinically significant complication following traumatic brain injury (TBI). Metabolic abnormalities are described after TBI in two cases. A 21 year old male injured in a motor vehicle accident admitted in a minimally responsive condition presented with fluctuating high sodium levels, undetectable serum testosterone, and depressed cortisol and thyroid function. Imaging revealed near complete avulsion of the pituitary stalk leading to panhypopituitarism. A 38 year old male admitted for occipital skull fractures and brain contusions presented with hyponatremia and low serum testosterone. Both patients required hormonal replacement and correction of electrolyte abnormalities. A screening protocol adapted for selected patients at risk for endocrine problems is described. While neuroendocrine screening is not advocated in all TBI patients, physicians should be aware of the importance of neuroendocrine dysfunction following TBI.

Adult↗
PubMed1976

The effect of the kVp level on EMI values. Selective imaging of various materials with different kVp settings.

A variety of materials and tissues as well as 3 patients were studied with the EMI scanner using the 100-, 120-, and 140-kVp settings. There was little shift in the EMI value for most tissues over this range, but significant shifts occurred with materials whose effective atomic number was moderately different from that of water. Use of the highest kVp setting may improve visualization of low-contrast images by decreasing the noise caused by statistical fluctuations. This shift in EMI values can be used to determine the approximate amount of material of high atomic number present, such as calcium or iodine.

Calcium↗
PubMed2006

Pathological gambling in Parkinson's disease improves on chronic subthalamic nucleus stimulation.

Pathological gambling (PG) related to dopaminergic treatment in Parkinson's disease (PD) is part of a spectrum of behavioral disorders called the dopamine dysregulation syndrome (DDS). We describe a series of PD patients with preoperative active PG due to dopaminergic treatment from a total of 598 patients who have undergone surgery for subthalamic nucleus stimulation for disabling motor fluctuations. The patients had systematic open assessment of behavioral symptoms and standardized assessments of motor symptoms, mood, and apathy. Seven patients (6 men, 1 woman; age, 54 +/- 9 years; levodopa equivalent dose, 1,390 +/- 350 mg/day) had preoperative PG over a mean of 7 years, intolerant to reduction in medication. Six had nonmotor fluctuations and four had other behavioral symptoms consistent with a diagnosis of the DDS. After surgery, motor symptoms improved, allowing for 74% reduction of dopaminergic treatment, below the dosage of gambling onset. In all patients, PG resolved postoperatively after 18 months on average (range, 0-48), although transient worsening occurred in two. Improvement paralleled the time course and degree of reduction in dopaminergic treatment. Nonmotor fluctuations, off period dysphoria, and other symptoms of the DDS improved. Two patients developed persistent apathy. In conclusion, PG and other symptoms of the DDS-associated dopaminergic treatment improved in our patients following surgery. Dopaminergic dysregulation commonly attributed to pulsatile overstimulation of the limbic dopaminergic system may be subject to desensitization on chronic subthalamic stimulation, which has a relative motor selectivity and allows for decrease in dopaminergic treatment.

Adult↗
PubMed1983

Xanthine oxidase deficiency and 'Dalmatian' hypouricaemia: incidence and effect of exercise.

In order to study the effects of raising the hypoxanthine concentration in plasma on its metabolism and renal handling, the effects of intense exercise have been investigated in a patient with xanthine oxidase deficiency. Despite the 90-fold increased concentration of hypoxanthine in plasma above resting levels in normal individuals, the intracellular concentration of the initial product of hypoxanthine in cells, IMP, was unaffected. Evolution may have stabilized intracellular nucleotide concentrations against the large fluctuations in plasma hypoxanthine which occur during exercise. The renal handling of hypoxanthine is consistent with 'filtration'. In contrast, xanthine clearances may exceed those for creatinine and urinary concentrations do not correlate with those for creatinine; 'secretion' may be involved. Xanthine excretion may reflect guanine breakdown. A retrospective survey of urate concentrations in blood from 47 420 patients followed by further selected investigations detected 2 women with persistent marked hypouricaemia and high urinary urate clearances, 'Dalmatian' hypouricaemia. High pressure liquid chromatographic analysis of plasma extracts can distinguish xanthine oxidase deficiency from other causes of hypouricaemia.

Erythrocytes↗
PubMed1988

Effects of changing hypothalamic temperature on eccrine sweating in the patas monkey.

Two male (10-13 kg) patas monkeys (Erythrocebus patas) were implanted with bilateral thermodes to control hypothalamic temperature. Animals were restrained in primate chairs and instrumented to yield hypothalamic (THYPO), colonic (Tc), and mean skin (Tsk) temperatures, chest sweat rate (mSW), and heart rate (HR). THYPO was monitored using a thermocouple inserted to the tip of a non-perfused thermode; mSW was measured using resistance hygrometry. After the monkey equilibrated to a selected ambient temperature, four thermodes were perfused with water from a temperature-controlled bath. Increasing THYPO from 37 to 41 degrees C increased mSW from 0.05 to 0.30 mg.cm-2.min-1. Reducing Tsk shifted the THYPO:mSW relationship to the right (p less than 0.05) without significantly altering its slope. Activity-induced changes in HR, when THYPO was constant, caused fluctuations in ongoing sweating that closely tracked HR. We conclude that mSW in the patas monkey is controlled by both peripheral and central thermal inputs and nonthermal factors.

Animals↗
PubMed2004

Channel-forming activity in the venom of the cockroach-hunting wasp, Ampulex compressa.

The parasitoid solitary wasp Ampulex compressa uses the cockroach Periplaneta americana as a food supply for its larvae. To subdue its prey, the wasp injects a venom cocktail into the brain of the cockroach. We investigated channel activity of A. compressa venom by collecting venom and incorporating it into a planar lipid bilayer. The venom, reconstituted into the bilayer, showed ion channel activity, forming a fast-fluctuating channel with a small conductance of 20+/-0.1pS, with no voltage sensitivity. These channels were not observed when the venom was digested with proteases before application to the bilayer, but were not affected by exposure to protease after their incorporation into the bilayer, indicating that the active venom component is a peptide. The channels were found to be cation selective with similar selectivity for the monovalent cations K(+), Li(+) and Na(+), but showed high selectivity against anions (Cl(-)) and divalent cations (Ca(2+) and Mg(2+)). This study is the first demonstration and biophysical characterization of channel activity in the venom of A. compressa. The possible functional significance of this channel activity is discussed in light of the unusual nature of the effects of this wasp venom on the behavior of its prey.

Animals↗
PubMed2001

Factors affecting the distribution of hydrocarbon contaminants and hydrogeochemical parameters in a shallow sand aquifer.

The distributions of hydrocarbon contaminants and hydrogeochemical parameters were investigated in a shallow sand aquifer highly contaminated with petroleum hydrocarbons leaked from solvent storage tanks. For these purposes, a variety of field investigations and studies were performed, which included installation of over 100 groundwater monitoring wells and piezometers at various depths, soil logging and analyses during well and piezometer installation, chemical analysis of groundwater, pump tests, and slug tests. Continuous water level monitoring at three selected wells using automatic data-logger and manual measuring at other wells were also conducted. Based on analyses of the various investigations and tests, a number of factors were identified to explain the distribution of the hydrocarbon contaminants and hydrogeochemical parameters. These factors include indigenous biodegradation, hydrostratigraphy, preliminary pump-and-treat remedy, recharge by rainfall, and subsequent water level fluctuation. The permeable sandy layer, in which the mean water table elevation is maintained, provided a dominant pathway for contaminant transport. The preliminary pump-and-treat action accelerated the movement of the hydrocarbon contaminants and affected the redox evolution pattern. Seasonal recharge by rain, together with indigenous biodegradation, played an important role in the natural attenuation of the petroleum hydrocarbons via mixing/dilution and biodegradation. The water level fluctuations redistributed the hydrocarbon contaminants by partitioning them into the soil and groundwater. The identified factors are not independent but closely inter-correlated.

Biodegradation, Environmental↗
PubMed1989

Evaluation of three circadian rhythm questionnaires with suggestions for an improved measure of morningness.

Circadian rhythms, cyclic fluctuations in many physiological and psychological functions, are thought to influence adjustment to shiftwork. A widely acknowledged individual difference in circadian rhythms, commonly called morningness, indicates preferences associated with morning or evening activities. Various self-report instruments have been developed to measure morningness, although little measurement data have been published for these scales. Because morningness scales are being used to select workers for night shiftwork, psychometric evaluations of these scales are needed. Psychometric assessments of undergraduate responses (N = 501) on three widely used scales indicate internal (interitem) measurement deficiencies in all three. Therefore, a 13-item scale was developed that distills the best items from two of these scales. Relationships between the new composite scale and external criteria are comparable with or stronger than similar relationships between the published scales and external criteria.

Circadian Rhythm↗
PubMed2005

Neutron scattering reveals the dynamic basis of protein adaptation to extreme temperature.

To explore protein adaptation to extremely high temperatures, two parameters related to macromolecular dynamics, the mean square atomic fluctuation and structural resilience, expressed as a mean force constant, were measured by neutron scattering for hyperthermophilic malate dehydrogenase from Methanococcus jannaschii and a mesophilic homologue, lactate dehydrogenase from Oryctolagus cunniculus (rabbit) muscle. The root mean square fluctuations, defining flexibility, were found to be similar for both enzymes (1.5 A) at their optimal activity temperature. Resilience values, defining structural rigidity, are higher by an order of magnitude for the high temperature-adapted protein (0.15 Newtons/meter for O. cunniculus lactate dehydrogenase and 1.5 Newtons/meter for M. jannaschii malate dehydrogenase). Thermoadaptation appears to have been achieved by evolution through selection of appropriate structural rigidity in order to preserve specific protein structure while allowing the conformational flexibility required for activity.

Amino Acid Sequence↗
PubMed2005

Glaucoma medication and aqueous humor dynamics.

PURPOSE OF REVIEW: This review evaluates current concepts regarding the effects of glaucoma medication on aqueous humor dynamics and the impact of this on intraocular pressure control and drug selection in clinical practice. RECENT FINDINGS: Calculations based on the Friedenwald and Goldmann equations have predicted that glaucoma medications that increase pressure-sensitive aqueous outflow will dampen intraocular pressure spikes and therefore may be advantageous over drugs that do not increase outflow facility. SUMMARY: Further experimental research is required to verify the influence of increased outflow facility on intraocular pressure fluctuation and the effect of this on glaucoma progression.

Animals↗
PubMed1986

Experience with multiple intracranial haematomas in New South Wales.

A retrospective survey of head injuries in NSW in 1977 and 1978 was conducted by the Trauma Subcommittee of the Neurosurgical Society of Australasia. This paper describes the findings for 129 patients who had more than one significant intracranial haematoma. Overall, the case fatality rate for these patients was 85%. The presence of low or fluctuating blood pressure was associated with a significantly higher mortality than in the rest of the group. Bilateral reacting pupils or an improvement in level of consciousness following decompressive surgery carried a more favourable prognosis. There was 100% fatality if surgery was not carried out or if the bleeding was not found at operation. A subset of patients who died was selected on the basis of a calculated prognostic variable, and compared with a similar subset of survivors. A higher proportion of patients who died had a delay in the provision of definitive treatment and failure to correct shock. This comparison was made on two criteria. Using the first accepted optimal treatment in 1984, nearly all cases were treated suboptimally, as might be expected. Using the second, acceptable treatment in 1977-78, it was calculated that between nine and 12 patients died with MIH in NSW in the 2 years of the survey, whose deaths might have been prevented.

Accidents, Traffic↗
PubMed1998

Biological and biochemical characteristics of cytoadhesion of Plasmodium falciparum-infected erythrocytes to chondroitin-4-sulfate.

The cytoadhesion of Plasmodium falciparum laboratory strains and clones to Saimiri brain microvascular endothelial cells (SBEC 17), with chondroitin-4-sulfate (CSA) as the only adhesion receptor, was tested. Only one strain had significant cytoadhesion. However, CSA-specific infected erythrocytes (IRBCs) were detected in all strains after selection of a CSA-specific subpopulation by culturing the few adherent IRBCs. This demonstrates the lack of sensitivity of cytoadhesion microassays for detecting small quantities of CSA-specific IRBCs in cultures or field isolates. Cytoadhesion to CSA is maximal at 24 h of the cycle and decreases with the onset of schizogony, reaching a minimum just before reinvasion. This fluctuation must be taken into account in comparisons of the cytoadhesion of different strains or isolates. The minimum size of CSA for active inhibition was 4 kDa, and a mass of 9 kDa was required for inhibition similar to that obtained with the 50-kDa CSA. In contrast to cytoadhesion to CSA, which is pH independent or maximal at physiological pH (depending on the target endothelial cells), adhesion to CD36 and intercellular adhesion molecule 1 was pH dependent, requiring acidic conditions to be maximal in all cases. Cytoadhesion to CSA may trigger the occlusion of microvessels and cause the acidosis necessary for the other receptors to be fully efficient. If this key role in the mechanisms of sequestration were to be confirmed in vivo, prevalence studies of the CSA cytoadhesion phenotype would have to be reevaluated, because simple cytoadhesion assays do not detect CSA-specific parasites present in very low numbers, and these parasites might then be undetected in the peripheral blood but present in organs in which sequestration occurs, such as the placenta (M. Fried and P. E. Duffy, Science 272:1502-1504, 1996).

Animals↗
PubMed2002

Activity-dependent development of axonal and dendritic delays, or, why synaptic transmission should be unreliable.

Systematic temporal relations between single neuronal activities or population activities are ubiquitous in the brain. No experimental evidence, however, exists for a direct modification of neuronal delays during Hebbian-type stimulation protocols. We show that in fact an explicit delay adaptation is not needed if one assumes that the synaptic strengths are modified according to the recently observed temporally asymmetric learning rule with the downregulating branch dominating the upregulating branch. During development, slow, unbiased fluctuations in the transmission time, together with temporally correlated network activity, may control neural growth and implicitly induce drifts in the axonal delays and dendritic latencies. These delays and latencies become optimally tuned in the sense that the synaptic response tends to peak in the soma of the postsynaptic cell if this is most likely to fire. The nature of the selection process requires unreliable synapses in order to give successful synapses an evolutionary advantage over the others. The width of the learning function also determines the preferred dendritic delay and the preferred width of the postsynaptic response. Hence, it may implicitly determine whether a synaptic connection provides a precisely timed or a broadly tuned "contextual" signal.

Animals↗
PubMed1981

An holistic approach to Ménière's disease. Medical and surgical management.

A review of the medical and surgical management of 195 patients with Meniere's disease is presented. In order to avoid a piecemeal approach to the problem of Meniere's disease, the "whole" patient must be treated. Psychological counseling, medical management, and when indicated selective surgical management is advocated. The diagnosis of Meniere's must be confirmed through careful history, physical, neurological evaluation and selective testing. The majority of patients can be controlled medically; however, in this study 52 (26%) patients underwent surgical therapy. Twenty-eight patients underwent some type of saccus surgery for Meniere's disease with overall relief of 71%; however, better relief of vertigo was seen with labyrinthectomy and nerve section. The most common indication for surgery was disabling vertigo. However, fluctuating progressive sensorineural loss, may be an important reason to advise surgery. Surgical techniques for Meniere's disease continue to evolve. A graduated approach is preferred, starting with endolymphatic-mastoid shunt, proceeding to middle fossa vestibular nerve section when medical status and hearing and adequate. When hearing is socially inadequate, labyrinthectomy with or without vestibular nerve section is preferred. A good working relationship with a neurosurgeon is advised for otolaryngologists performing middle fossa surgery.

Counseling↗
PubMed1986

Plasma levels of luteinizing hormone, growth hormone, and estradiol from six weeks of age to sexual maturity in two lines of chickens selected for low or high abdominal fat content.

An experiment was conducted to investigate possible differences in plasma hormone levels between females of two lines of chickens selected for high (FL) or low (LL) abdominal fat content. Blood was taken at weekly intervals from 6 weeks of age to sexual maturity, and assays were performed for luteinizing hormone (LH), growth hormone (GH), and estradiol (E2). Age-related increases in the plasma titers of LH and estradiol were found while GH remained low apart from initial and final fluctuations. There was no difference between the strains in plasma E2, only minor differences in plasma GH, but a clear-cut difference was observed in plasma LH during the prepubertal period. Plasma LH tended to be higher in the LL, but the reason for this remains unclear.

Adipose Tissue↗
PubMed1982

Thyroid uptake measurements with I-123: problems and pitfalls: concise communication.

The measurement of radioiodine uptake is generally considered to be straight-forward and accurate. However, during the past two decades, discrepancies in "normal" thyroid uptake values have been noticed between Montefiore Hospital and Medical Center and the Hospital of Albert Einstein College of Medicine. These differences were attributed to differences in patient population. Further investigation revealed that the persisting uptake discrepancies arose from neck-phantom differences and variations in procedure. Differences in presumably standardized neck-phantom attenuation characteristics have been shown to cause large variations in count rates from I-123 and I-131 standard capsules. The effect of high-voltage fluctuation on phantom count rates is more pronounced with I-123 than with I-131. In constant levels of high-energy contaminants in I-123 also affect the uptake measurements. large errors in the measurements of thyroid uptake values may result from seemingly unimportant variations in technique. A stable high-voltage power supply, precise high-voltage adjustment, careful selection of energy window, and the use of a standardized neck phantom with generally accepted attenuation characteristics are absolutely essential if RAIU values are to be compared and appropriate therapeutic doses are to be administered based on these measurements.

Humans↗
PubMed1975

Deviations from compositional randomness in eukaryotic and prokaryotic proteins: the hypothesis of selective-stochastic stability and a principle of charge conservation.

Eight proteins of diverse lengths, functions, and origin, are examined for compositional non-randomness amino acid by amino acid. The proteins investigated are human fibrinopeptide A, guinea pig Insulin, rattlesnake cytochrome c, MS2 phage coat protein, rabbit triosephosphate isomerase, bovine pancreatic deoxyribonuclease A, bovine glutamate dehydrogenase, and Bacillus thermoproteolyticus thermolysin. As a result of this study the experimentally testable hypothesis is put forth that for a large class of proteins the ratio of that fraction of the molecule which exhibits compositional non-randomness to that fraction which does not is on the average, stable about a mean value (estimated as 0.32 plus or minus 0.17) and (nearly) independent of protein length. Stochastic and selective evolutionary forces are viewed as interacting rather than independent phenomena. With respect to amino acid composition, this coupling ameliorates the current controversy over Darwinian vs. non-Darwinian evolution, selectionist vs. neutralist, in favor of neither: Within the context of the quantitative data, the evolution of real proteins is seen as a compromise between the two viewpoints, both important. The compositional fluctuations of the electrically charged amino acids glutamic and aspartic acid, lysine and arginine, are examined in depth for over eighty protein families, both prokaryotic and eukaryotic. For both taxa, each of the acidic amino acids is present in amounts roughly twice that predicted from the genetic code. The presence of an excess of glutamic acid is independent of the presence of an excess of aspartic acid and vice versa.

Amino Acids↗