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Biomedical subjects

J C King

Publications and source records attributed to J C King.

At least 19 recordsLinked to original sources
PubMed2006

A proposed method for assessing plasma hypertonicity in vivo.

Indices of plasma hypertonicity, elevated plasma concentrations of solutes that draw fluid out of cells by osmosis, are needed to pursue hypertonicity as a possible risk factor for obesity and chronic disease. This paper proposes a new index that may be more sensitive to mild hypertonicity in vivo at a point in time than traditional measures. The index compares mean corpuscular volume (MCV) estimates from diluted (in solution by automated cell counter) and nondiluted blood (calculated from manual hematocrit, MCV=Hct/RBC*10(6)). A larger Auto vs Manual MCV (>2 fl) in vitro indicates hypertonicity in vivo if the cell counter diluent is isotonic with the threshold for plasma vasopressin (PVP) release and PVP is detectable in plasma (>0.5 pg/ml). To evaluate this principle of concept, hypertonicity was induced by 24-h fluid restriction after a 20 ml/kg water load in four healthy men (20-46 years). Unlike serum and urine indices, the MCV difference-&-PVP index detected hypertonicity in all participants.

Adult↗
PubMed2004

Metabolomics in the opening decade of the 21st century: building the roads to individualized health.

It is rapidly becoming possible to measure hundreds or thousands of metabolites in small samples of biological fluids or tissues. This makes it possible to assess the metabolic component of nutritional phenotypes and will allow individualized dietary recommendations. ASNS has to take action to ensure that appropriate technologies are developed and that metabolic databases are constructed with the right inputs and organization. The relations between diet and metabolomic profiles and between those profiles and health and disease must be established. ASNS also should consider the social implications of these advances and plan for their appropriate utilization.

Animals↗
PubMed2003

A method of preserving and testing the acceptability of gac fruit oil, a good source of beta-carotene and essential fatty acids.

Gac fruit (Momordica cochinchinensis Spreng) is indigenous to Vietnam and other countries in Southeast Asia. Its seed pulp contains high concentrations of carotenoids, especially the provitamin A, beta-carotene. In northern Vietnam, gac fruits are seasonal and are mainly used in making a rice dish called xoi gac. The purpose of this study was to develop a method to collect and preserve gac fruit oil, to evaluate the nutritional composition of the oil, and to assess the acceptability of the gac oil by typical Vietnamese homemakers. One hundred women participated in training to learn how to prepare the fruits and operate the oil press. The women also participated in a survey of gac fruit use and their habitual use of animal fat and vegetable oil. Among all the participants in the training and surveys, 35 women actually produced oil from gac fruits grown in the village, using manual oil presses and locally available materials. The total carotene concentration in gac fruit oil was 5,700 micrograms/ml. The concentration of beta-carotene was 2,710 micrograms/ml. Sixty-nine percent of total fat was unsaturated, and 35% of that was polyunsaturated. The average daily consumption of gac fruit oil was estimated at 2 ml per person. The daily beta-carotene intake (from gac fruit oil) averaged approximately 5 mg per person. It was found that gac oil can be produced locally by village women using manual presses and locally available materials. The oil is a rich source of beta-carotene, vitamin E, and essential fatty acids. Although the beta-carotene concentration declines with time without a preservative or proper storage, it was still high after three months. The oil was readily accepted by the women and their children, and consumption of the oil increased the intake of beta-carotene and reduced the intake of lard.

Adolescent↗
PubMed2001

Digit distribution of proper digital nerve action potential.

Antidromic sensory nerve action potential testing is well characterized and commonly used to assess the sensory component of the upper limb median and ulnar nerves. The final terminal segments of these nerves are the proper digital nerves. Ring recording electrodes are commonly used to detect the proper digital nerves' antidromic responses. Attempts to record the separate contributions of individual digital nerves along the lateral aspects of each finger, using small surface electrodes, is shown to be unreliable for determining the integrity of a single terminal digital branch. We found between 50% to 77% of the stimulated terminal branch's response amplitude when recorded at electrodes positioned over the nonstimulated branch located 180 degrees from the activated terminal branch. Detecting a single terminal nerve response was achieved by using the fourth digit and the second digit with one of the second digit's branches neurophysiologically blocked by local anesthetic. The volume-conducted response from the opposite side of the finger resulted in this relatively large recorded response, which remains within the range of reference values precluding the simple use of antidromic techniques to assess injury to a single proper digital nerve. Techniques are proposed to avoid such pitfalls and to assess most accurately the desired response.

Action Potentials↗
PubMed2001

Effect of acute zinc depletion on zinc homeostasis and plasma zinc kinetics in men.

BACKGROUND: Zinc homeostasis and normal plasma zinc concentrations are maintained over a wide range of intakes. OBJECTIVE: The objective was to identify the homeostatic response to severe zinc depletion by using compartmental analysis. DESIGN: Stable zinc isotope tracers were administered intravenously to 5 men at baseline (12.2 mg dietary Zn/d) and after 5 wk of acute zinc depletion (0.23 mg/d). Compartmental modeling of zinc metabolism was performed by using tracer and mass data in plasma, urine, and feces collected over 6-14 d. RESULTS: The plasma zinc concentration fell 65% on average after 5 wk of zinc depletion. The model predicted that fractional zinc absorption increased from 26% to essentially 100%. The rate constants for zinc excretion in the urine and gastrointestinal tract decreased 96% and 74%, respectively. The rate constants describing the distribution kinetics of plasma zinc did not change significantly. When zinc depletion was simulated by using an average mass model of zinc metabolism at baseline, the only change that accounted for the observed fall in plasma zinc concentration was a 60% reduction in the rate constant for zinc release from the most slowly turning over zinc pool. The large changes in zinc intake, excretion, and absorption-even when considered together-only explained modest reductions in plasma zinc mass. CONCLUSION: The kinetic analysis with a compartmental model suggests that the profound decrease in plasma zinc concentrations after 5 wk of severe zinc depletion was mainly due to a decrease in the rate of zinc release from the most slowly turning over body zinc pool.

Adult↗
PubMed2001

Nutrition: a reservoir for integrative science.

In the last twenty years, powerful new molecular techniques were introduced that made it possible to advance knowledge in human biology using a reductionist approach. Now, the need for scientists to deal with complexity should drive a movement toward an integrationist approach to science. We propose that nutritional science is one of the best reservoirs for this approach. The American Society for Nutritional Sciences can play an important role by developing and delivering a cogent message that convinces the scientific establishment that nutrition fills this valuable niche. The society must develop a comprehensive strategy to develop our image as the reservoir for life sciences integration. Our efforts can start with our national meeting and publications, with the research initiatives for which we advocate, with our graduate training programs and with the public relations image we project for ourselves. Defining the image and future directions of nutrition as the discipline that can integrate scientific knowledge from the cell and molecule to the whole body and beyond to populations can be the most important task that our society undertakes. If we do not effectively meet this challenge, a golden opportunity will pass to others and nutritional scientists will be left to follow them.

Biological Science Disciplines↗
PubMed2001

Effect of reproduction on the bioavailability of calcium, zinc and selenium.

Nutrient needs increase during pregnancy and lactation to support fetal growth and milk synthesis, respectively. Physiological adjustments that are made to meet those needs alter the fraction of ingested nutrient retained, or the bioavailability. Using stable isotopes as tracers, we measured calcium, zinc and selenium homeostasis in women during reproduction. The physiological response, and therefore the bioavailability, of these three minerals differed during reproduction. Calcium absorption increased approximately 2-fold during pregnancy but dropped to values for nonpregnant women during lactation. The calcium needs for lactation were met by renal conservation and bone resorption. In women chronically consuming a low calcium diet, fractional calcium absorption increased to >80% during reproduction. Zinc absorption tended to increase during pregnancy and lactation; renal conservation was not evident at any time during the reproductive cycle. Selenium absorption was high, approximately 80% of intake, in both pregnant and nonpregnant women. Pregnant women conserved selenium by decreasing urinary selenium excretion. Studies defining the impact of maternal status and the dietary mineral source and amount on mineral bioavailability are needed to determine the potential benefits of mineral supplementation during reproduction.

Biological Availability↗
PubMed2001

Accuracy of simple techniques for estimating fractional zinc absorption in humans.

The theoretical basis of the accuracy of a number of simple techniques for estimating fractional zinc absorption (FZA) in humans using stable isotopic tracers has not been evaluated. These techniques include fecal monitoring (FM), deconvolution analysis (DA), double isotopic tracer ratio (DITR) and indicator dilution methods. Using a compartmental model, we investigated the accuracy and logic of each of these techniques. Time-dependent estimates of FZA based on the simple techniques were simulated using the compartmental model and compared with the known FZA derived from the model. The analysis elucidated logical errors in some of the FM techniques, and even when these problems were corrected, the FM technique was still prone to errors due to incomplete fecal tracer recovery and variable gastrointestinal (GI) transit time. Although logically correct, the indicator dilution techniques were also highly sensitive to incomplete fecal tracer recovery and variable GI transit time. The DA and DITR techniques were the most robust in that they were logically correct and were insensitive to incomplete fecal tracer recovery and variable GI transit time. Although all of the DA and DITR methods provided similarly good estimates of FZA relative to the compartmental model, the DITR technique performed on a spot urine specimen obtained several days after tracer administration was the preferred choice because of its simplicity and minimal requirements for patient compliance.

Body Fluid Compartments↗
PubMed2001

Exchangeable zinc pool masses and turnover are maintained in healthy men with low zinc intakes.

Previous studies suggest that rapidly exchanging zinc pools (EZP), thought to supply the zinc required by tissues, are smaller and turn over more rapidly in individuals with lower zinc intakes. We studied the effects of low dietary zinc (4.6 mg/d) on EZP mass and turnover in seven healthy men confined during a 20-wk clinical study. Supplements of 9.1 mg zinc were given during the 5-wk baseline and repletion periods, and placebos were given during a 10-wk zinc-restriction period. Stable 70Zn tracers were administered intravenously at the end of baseline, 3 and 10 wk after the start of zinc restriction and at the end of repletion. Multiple plasma samples were collected over an 8-d period after tracer administration. 70Zn:66Zn ratios were measured using inductively coupled plasma mass spectrometry, and tracer-tracee data were analyzed by compartmental modeling. Activities of the zinc-dependent enzymes, alkaline phosphatase and 5'nucleotidase, were unchanged during the study. There were no significant changes in EZP masses or kinetic parameters. A three-compartment model indicated that the masses of plasma zinc and total EZP averaged 3.25 +/- 0.58 and 147.8 +/- 33.2 mg, respectively, at the four time points studied. Plasma zinc mass turned over at an average of 5.3 times per hour. There was an 11% reduction (P = 0.06) in plasma zinc flux 3 wk after the start of the low zinc diet period, but it returned to baseline values after 10 wk of zinc restriction. The results suggest that total EZP mass is maintained when dietary zinc is reduced to 4.6 mg/d over a 10-wk period.

Adult↗
PubMed2001

Prevalence of denervation in paraspinal and foot intrinsic musculature.

OBJECTIVE: The primary purpose of this investigation was to determine the prevalence of abnormal spontaneous activity (positive sharp waves (PSWs) and fibrillation potentials (FPs)) in selected lumbosacral paraspinal and foot intrinsic muscles in an asymptomatic healthy population. DESIGN: This was a prospective assessment of 50 individuals without history or physical findings suggestive of peripheral neuromuscular disease whereby a monopolar needle electrode was located in the unilateral L4 and L5 paraspinal as well as abductor hallucis and extensor digitorum brevis muscles. These muscles were extensively evaluated for the presence of PSWs, FPs, and fasciculation potentials. RESULTS: Ten subjects per decade from 20-59 yr and ten subjects from 60-80 yr comprised the 50 participants (28 women), resulting in a mean age of 45+/-15.9 (range, 20-76) yr. A single individual (prevalence, 2%) demonstrated fibrillation potentials in the extensor digitorum brevis, and FPs and PSWs were detected in two subjects' (4% prevalence) L4/L5 paraspinal muscles. Ninety-four percent of the subjects had fasciculation potentials in the abductor hallucis, whereas 60% had these waveforms in the extensor digitorum brevis. Only 6% of subjects had fasciculation potentials in the L4 but not L5 paraspinal muscles. All subjects demonstrated both prototypical and "atypical" appearing endplate spikes in all of the muscles examined. CONCLUSIONS: We failed to confirm the previously reported prevalence of FPs and PSWs in both the paraspinal and foot intrinsic musculature. Atypical appearing endplate spikes, however, display configurations similar to FPs and PSWs and were present in all subjects. Failure to pay close attention to the discharge rate and rhythm of endplate spikes can lead to misinterpreting these waveforms as FPs and PSWs. It is likely that the previously reported high prevalence of spontaneous activity in healthy persons resulted from not fully appreciating the similarity between innervated and denervated spontaneous single muscle fiber discharge configurations.

Action Potentials↗
PubMed2001

Isolated sural neuropathy presenting as lateral ankle pain.

A case of job-related, unilateral traumatic sural neuropathy causing severe lateral ankle pain and impaired work performance for a 26-yr-old female grocery clerk is reported. This diagnosis is made both clinically and electrophysiologically. We review the pertinent electrophysiologic features, anatomy, and clinical findings in our patient with an isolated sural neuropathy. A review of the literature demonstrates that trauma is the most common cause of this unusual isolated neuropathy. Despite its rare occurrence, it should be considered in patients who present with lateral ankle pain and concomitant loss of sensation in the sural nerve distribution. The establishment of a neuropathic origin assists with management strategies that will differ from the more common musculoskeletal causes of lateral ankle pain. After an appropriate diagnosis and treatment, an excellent outcome resulted for our patient.

Accidents, Occupational↗
PubMed2001

Safety, vaccine virus shedding and immunogenicity of trivalent, cold-adapted, live attenuated influenza vaccine administered to human immunodeficiency virus-infected and noninfected children.

OBJECTIVE: To assess the safety of live, attenuated influenza vaccine (LAIV) administered to relatively asymptomatic or mildly symptomatic HIV-infected children and non-HIV-infected children. METHODS: Twenty-five non-HIV and 24 HIV-infected children (CDC Class N or A1,2) were enrolled into this double blind, placebo-controlled study. Children were randomized within each HIV status group to one of two dosing regimens: Regimen 1, Dose 1 = LAIV, Dose 2 = placebo, Dose 3 = LAIV; or Regimen 2, Dose 1 = placebo, Dose 2 = LAIV, Dose 3 = LAIV. Study doses were separated by 28 to 35 days. Reactogenicity events within 10 days and adverse events within 28 to 35 days after each study dose were recorded. Blood HIV RNA concentrations, CD4 counts and CD4% were measured throughout the study on HIV-infected children. Quantitative influenza cultures were performed on nasal aspirates collected periodically from all children up to 28 to 35 days after each study dose. Influenza isolates were assessed for retention of the temperature-sensitive phenotype. Serum influenza HAI antibodies were measured before and after each LAIV vaccination. RESULTS: No significant differences were found in rates of reactogenicity events and vaccine-related adverse events after placebo or the first dose of LAIV within each HIV status group, nor were differences found between HIV-infected and HIV-uninfected children after each dose of LAIV. Overall none of the HIV-infected children experienced a significant LAIV-related serious adverse event or influenza-like illness, making the one sided 95% CI of such a serious event occurring after LAIV 0 to 12%. No significant changes in geometric mean HIV RNA concentrations, CD4 counts or CD4% or prolonged or increased quantity of LAIV virus shedding occurred in HIV-infected children after receiving either dose of LAIV. All recovered influenza isolates retained the temperature-sensitive phenotype. After two doses of LAIV, 83% of the non-HIV-infected and 77% of the HIV-infected children had a > or = 4-fold rise in influenza antibody to at least one of the three LAIV strains. CONCLUSION: If relatively healthy HIV-infected children become exposed to LAIV inadvertently, then serious adverse outcomes would not be expected to occur frequently.

Child↗
PubMed2001

Perinatal exposure to low doses of bisphenol A affects body weight, patterns of estrous cyclicity, and plasma LH levels.

The nonsteroidal estrogenic compound bisphenol A (BPA) is a monomer used in the manufacture of polycarbonate plastics and resins. BPA may be ingested by humans as it reportedly leaches from the lining of tin cans into foods, from dental sealants into saliva, and from polycarbonate bottles into their contents. Because BPA is weakly estrogenic--approximately 10,000-fold less potent than 17beta-estradiol--current environmental exposure levels have been considered orders of magnitude below the dose required for adverse effects on health. Herein we demonstrate measurable effects on the offspring of Sprague-Dawley female rats that were exposed, via their drinking water, to approximately 0.1 mg BPA/kg body weight (bw)/day (low dose) or 1.2 mg BPA/kg bw/day (high dose) from day 6 of pregnancy through the period of lactation. Offspring exposed to BPA exhibited an increase in body weight that was apparent soon after birth and continued into adulthood. In addition, female offspring exposed perinatally to the high dose of BPA exhibited altered patterns of estrous cyclicity and decreased levels of plasma luteinizing hormone (LH) in adulthood. Administration of neither the doses of BPA that caused effects during perinatal exposure nor a 10-fold higher dose was able to evoke a uterotropic response in ovariectomized postpubertal females. These data indicate an increased sensitivity to BPA during the perinatal period and suggest the need for careful evaluation of the current levels of exposure to this compound.

Administration, Oral↗
PubMed2001

Carpal tunnel syndrome and the Riche-Cannieu anastomosis: electrophysiologic findings.

Two cases of carpal tunnel syndrome with Riche-Cannieu anomalies are reported. Despite complete absence of a median nerve evoked compound muscle action potential from the thenar eminence, these patients had significant preservation of function and minimal muscle atrophy. Activation of the ulnar nerve at both the wrist and elbow generated easily obtainable compound muscle action potentials from the thenar eminence with initial negative onset. This observed preservation of function and electrophysiologic responses are best explained by the presence of a Riche-Cannieu anastomosis innervating the thenar eminence through branches from ulnar nerve. To our knowledge there has not been a report of similar cases in patients with profound carpal tunnel syndrome and a Riche-Cannieu anomaly. We review the clinical findings, the electrodiagnostic data, and the impact of a Riche-Cannieu anastomosis on advanced carpal tunnel syndrome.

Adult↗
PubMed2000

Group-specific antibody levels surrounding invasive pneumococcal illness in children infected with human immunodeficiency virus.

Pneumococcal antibody levels surrounding systemic pneumococcal illness (SPI) were measured in children infected with human immunodeficiency virus (HIV). Archived serum samples were collected from 28 HIV-infected children who had 34 cases of SPI, caused by pneumococcal groups 4, 6, 9, 14, 19, and 23. Serum samples collected within 23 weeks before and 13 weeks after the SPI were assayed by ELISA for antipneumococcal polysaccharide (PnPs) IgG antibody to 6 representative pneumococcal serotypes. There was a wide range (0. 16-30.80 microg/mL) of pre-SPI anti-PnPs antibody levels to the presumed infecting serotypes, with a geometric mean level of 0.83 microg/mL (n=34). Seventy-six percent of the antibody values were <2.0 microg/mL, and 95% were <5.0 microg/mL. Homologous seroresponses (>/=4-fold rise in anti-PnPs antibody) were detected in only 4 (27%) of 15 paired serum samples. Heterologous, noninfecting group seroresponses were detected frequently (72%) in the paired serum samples from these 4 homologous group seroresponders.

AIDS-Related Opportunistic Infections↗
PubMed2000

Cells containing immunoreactive estrogen receptor-alpha in the human basal forebrain.

The distribution of estrogen receptor protein-alpha (ER-alpha)-containing cells in the human hypothalamus and adjacent regions was studied using a monoclonal antibody (H222) raised against ER-alpha derived from MCF-7 human breast cancer cells. Reaction product was found in restricted populations of neurons and astrocyte-like cells. Neurons immunoreactive for ER-alpha were diffusely distributed within the basal forebrain and preoptic area, infundibular region, central hypothalamus, basal ganglia and amygdala. Immunoreactive astrocyte-like cells were noted within specific brain regions, including the lamina terminalis and subependymal peri-third-ventricular region. These data are consistent with the location of estrogen receptors in the basal forebrain of other species and the known effects of estrogens on the cellular functions of both neurons and supporting elements within the human hypothalamus and basal forebrain.

Amygdala↗
PubMed2000

Hybrid fibrillation potentials and positive sharp waves.

Fibrillation potential configurations are characterized as initially positive triphasic waveforms, whereas positive sharp waves appear biphasic with an initial positive deflection. Careful observation of single muscle fiber discharges in denervated muscle, however, can reveal many different-appearing and stable firing waveforms that resemble a bifid positive sharp wave or some form of combined fibrillation potential and positive sharp wave. In this investigation, a number of atypical-appearing single muscle fiber discharges are hypothesized to arise from particular interactions between the muscle fiber and recording electrode. Single muscle fiber potentials are modeled as originating from a single denervated muscle fiber's former endplate and midfiber region as well as from the fiber's tendinous termination for both a compressed and sealed end effect. The modeled waveforms' appearance corresponds well to those obtained clinically and the necessary interpotential summated templates' temporal domains are feasible for action potential termination at the electrode with subsequent reinitiation beyond the proposed peri-electrode compressed region. It is hypothesized that the majority of hybrid waveforms are the result of a single muscle fiber action potential terminating at a recording electrode while also initiating a "skipped" activation of the muscle fiber past the electrode resulting in the summation of two distinct time-locked waveforms.

Action Potentials↗