Search PubMed⌕ Search

Biomedical subjects

R Wong

Publications and source records attributed to R Wong.

At least 145 records · Page 8Linked to original sources
PubMed1992

In vivo skeletal muscle metabolism during dynamic exercise and recovery: assessment by nuclear magnetic resonance spectroscopy.

BACKGROUND: The purpose of this study was to define temporally phosphorus metabolism and pH in the gastrocnemius muscles of 21 normal adult subjects during rest, dynamic exercise to exhaustion, and early and late recovery. METHODS: In vivo nuclear magnetic resonance spectroscopy. RESULTS: At rest, the ratio of phosphocreatine to the alpha peak of ATP averaged 2.26 +/- 0.25, the inorganic phosphate to ATP ratio averaged 0.31 +/- 0.08 and pH averaged 7.10 +/- 0.04. The phosphorus metabolites exhibited immediate and progressive changes with exercise, reaching their minimum (phosphocreatine, 0.95 +/- 0.41) or maximum (inorganic phosphate, 1.95 +/- 0.75) values at exhaustion, after an average exercise of 11 +/- 4 mins. In contrast, pH changed slowly during early exercise, but fell abruptly thereafter and averaged 6.76 +/- 0.17 at exhaustion. Phosphocreatine and inorganic phosphate began to return rapidly towards preexercise values immediately on cessation of exercise. However, pH declined further in the period immediately following cessation of exercise, reaching a nadir of 6.56 +/- 0.24 an average of 2 mins into recovery. Exercise duration did not correlate highly with any metabolic variable. CONCLUSIONS: The data support the concept that the metabolic physiology underlying physical exhaustion of dynamic exercising muscle is multifactorial. The post exercise drop in pH also suggests that normal subjects have a greater contribution to high energy phosphate production from glycolysis, as opposed to oxidative metabolism, in early recovery.

Acid-Base Equilibrium↗
PubMed1991

T cell non-MHC-restricted antigen-binding molecules secreted or associated with the cell membrane are antigenically distinct.

Some T cells produce membrane-associated or soluble molecules which bind nominal antigen specifically (TABM) and effect immunoregulation or events similar to cell-mediated hypersensitivity. We have used polyclonal antisera raised against an azobenzene arsonate (ABA)-specific TABM secreted by an ABA-specific T cell hybrid or against TNP-specific polypeptides produced by immunoregulatory T cells to identify the expression of soluble (secreted) or membrane-associated TABM. Ascites fluid or culture medium containing a T cell hybrid or T cell lines, respectively, contain TABM recognized only by an antiserum specific for the secreted T cell hybrid (ABA-specific) derived TABM. Conversely, an antiserum that recognized the TNP-specific polypeptides detected cell-membrane associated TABM but did not bind TABM secreted by the T cell hybrid or cell lines.

Animals↗
PubMed1991

Does the retrocecal position of the vermiform appendix alter the clinical course of acute appendicitis? A prospective analysis.

Ninety-four adult patients undergoing appendectomy for acute appendicitis were prospectively studied during a 2-year period. Patients were divided into retrocecal (group 1; n = 27 [29%]) and anterior (group 2; n = 67 [71%]) groups according to the position of the appendix. There was no statistical difference between the two groups in duration of symptoms, presenting signs and symptoms, and initial white blood cell count. Furthermore, retrocecal appendicitis was not associated with a higher rate of perforation or increased morbidity. We conclude that the retrocecal position of the appendix does not alter the presentation of appendicitis.

Acute Disease↗
PubMed1991

Effects of naloxone on seizure latencies of black (a/a) Mongolian gerbils (Meriones unguiculatus).

The effects of the opiate antagonist, naloxone, on seizure tendencies of the black or nonagouti line of Mongolian gerbils (Meriones unguiculatus) carrying the a/a coat color allele was investigated. The animals were tested under the following conditions: mock infection; 0.9% NaCl injection; and naloxone at doses of 1, 2, 5, and 10 mg/kg body weight. The results indicated that when naloxone was at doses of 2 mg/kg body weight and higher, there was an increase in the animals' seizure latencies relative to that manifested under the basal condition.

Animals↗
PubMed1991

Value of lymph node biopsy in the treatment of patients with the human immunodeficiency virus.

The indications and value of lymph node biopsy in patients infected with the human immunodeficiency virus (HIV) are not clearly defined. We reviewed 29 consecutive lymph node biopsies performed on 24 patients with the HIV over a 4-year period. Indications for biopsy included: (1) new or worsening medical symptoms with no detectable etiology in patients with lymphadenopathy, (2) disproportionately larger or enlarging lymph node in patients with generalized adenopathy, and (3) exclusion of concomitant disease in patients with previously defined infectious or neoplastic processes. The biopsy samples exhibited a diversity of histologic appearances including atypical and reactive hyperplasia, malignancy, and infection. Nineteen biopsies (64%) resulted in the institution or alteration of treatment. The absolute number of T-helper cells prior to biopsy was significantly lower in patients with a diagnosis of malignancy or infection (p < 0.05), as well as in those who eventually died (p < 0.05). Four (14%) minor complications resulted from lymph node biopsy. Based on our results, we conclude that lymph node biopsy is indicated in the above three subsets of HIV-infected patients. Biopsy can be performed with minimal morbidity and significantly alters therapy in the majority of patients.

AIDS-Related Complex↗
PubMed1991

Immunophenotyping in the management of gastric lymphoma.

Primary gastric lymphoma is a rare tumor in which surgical resection plays a major role in improving the response rate and reducing the incidence of bleeding and perforation after chemotherapy. In 17 consecutive patients, the diagnosis of gastric lymphoma was made by immunophenotyping snap-frozen endoscopic biopsy specimens. All neoplasms were B-cell lymphomas. Pan B surface marker antigens were present in all patients. Levels of Ki-67, a nuclear marker of tumor proliferation, were greater than 45% in two of the four patients who died after progression of their lymphoma. All patients alive had Ki-67 levels of less than 30%. A lower proliferation index, as measured by Ki-67, appears to be associated with better prognosis. Ten of 11 patients treated by resection prior to chemotherapy had no complications. Immunophenotyping is the key in the differential diagnosis when considering malignant lymphoma with gastric carcinoma and benign conditions such as pseudolymphoma.

Adult↗
PubMed1991

Clinical implications of I-125 dosimetry of bone and bone-soft tissue interfaces.

The dose to bone from I-125 photon interactions is expected to be approximately five times greater than the dose to soft tissue for the same photon fluence because of the dominance of the photoelectric effect. However, adverse clinical effects are not observed for I-125 implants near bone. Both the strong absorption of I-125 photons in bone and the narrowness (about 10 mu) of the high dose transition zone at a bone-soft tissue interface act to limit the volume of radiation sensitive tissue in the high dose region. Examples of calculated implant dose distributions in bone and in soft tissue cavities in bone are presented. Radiobiological measurements are consistent with the theoretical interface calculations. Calculation of the macroscopic dose distribution uses a recently measured radial dose function, while at the bone-soft tissue interface an analytic theory of the transition zone that is applicable to regular shaped cavities is used. Radiobiological experiments comparing cell survival for cells irradiated with 70 kvP X rays at Al-water and polystyrene-water interfaces are consistent with the transition zone calculations.

Bone and Bones↗
PubMed1991

Atherosclerosis in diabetes and hypertension. A comparative morphometric study of their progression using an atherometric system.

The three major epicardial coronary arteries of a set of 472 autopsy cases divided into four groups: a) non-diabetics and non-hypertensive, 322 subjects; b) hypertensive, 75 subjects; c) diabetics, 57 subjects and d) hypertensive and diabetic, 17 subjects, were studied. Classical pathomorphological procedures and an atherometric system (AS), suitable to characterize the atherosclerotic lesions, was used searching for differences between the level of atherosclerosis into these four groups and its eventual progression according to the time of evolution of these diseases. Raw data processing was full automated and some univariate and multivariate statistical procedures (means, standard deviations, ANOVA, MANOVA and principal components analysis) were performed using two commercial statistical packages: "NCSS" and "SYSTAT". The most remarkable findings were the following: Diabetes and hypertension have both strong impact upon the rate at which the atherosclerotic process takes place in subjects affected by these diseases. The time of evolution of both diseases correlates positively and independently of age with the velocity of the atherosclerotic process at the three coronary arteries. The impact of diabetes seems to be stronger and is particularly expressed by the severe plaques (Z) while the effect of hypertension is specially observable at the fibrous plaques (Y). There seems to be no significant interaction (synergism) between the two risk factors upon the measurement of the atherosclerotic lesions, that is, they have an additive effect. Two simple underlying factors can be used to account for interindividual differences. These two factors are "dominated", respectively, by fibrous (Y) and severe plaques (Z).

Analysis of Variance↗
PubMed1991

Anticardiolipin antibodies and lupus anticoagulant in Chinese patients with systemic lupus erythematosus.

Ninety-one consecutive patients with systemic lupus erythematosus (SLE) were studied. Forty-two patients had positive anticardiolipin antibodies (aCl) 40 aCl-IgG (44.4%); 4 aCl-IgA (4.4%); 1 aCl-IgM (1.1%). One patient had both aCl-IgG and aCl-IgA and 1 patient had aCl-IgG, aCl-IgA and aCl-IgM. Ten patients (11.1%) had lupus anticoagulant (LA). Both aCl isotypes and LA had no statistical association with thrombosis or thrombocytopenia.

Adolescent↗
PubMed1991

Complications associated with needle localization biopsy of the breast.

A review of 144 consecutive needle localization biopsies of the breast (NLBB) was performed to assess complications associated with this procedure. Thirty-four complications occurred in 27 patients. There were 11 wound infections associated with NLBB. During this time period, there were 1,583 clean general surgical operations performed, other than biopsy of the breast, yielding an over-all wound infection rate of 1.2 per cent (p less than 0.001). A trend was noted, suggesting that use of drains may have contributed to wound infection versus no drainage (25 versus 5 per cent, respectively). Electrocautery burns requiring local wound care occurred during seven biopsies and four of these patients subsequently had a wound infection develop. Four lesions required more than one excision to remove the abnormal mammary tissue, and in four, there was a failure to remove the lesion at the first operation. Fifty-three localization procedures were performed using methylene blue. In this group, only one patient required more than one biopsy to remove the abnormal mammary tissue, and there were no failures with this technique. Also, a smaller mean volume of tissue was removed in this group versus the standard NLBB (30.2 +/- 3.0 versus 53.3 +/- 4.6 cubic millimeters, respectively) (p less than 0.01). Four cardiovascular complications occurred, requiring overnight admission. All of these patients were more than 65 years old and had the procedure performed while under general anesthesia. Patient age, type of anesthesia, resident versus attending surgeon and length of procedure had no independent effect on local complication rate.

Aged↗
PubMed1990

Changes in conserved region 2 of Escherichia coli sigma 70 affecting promoter recognition.

We describe a mutation in rpoD, the gene encoding the sigma 70 subunit of RNA polymerase, which alters the promoter specificity of the holoenzyme in vivo. The mutant sigma causes a substantial and specific increase in the activity of mutant ant and lac promoters with a T.A to C.G substitution at position -12, the first position of the -10 hexamer. The rpoD mutation is a single base-pair substitution causing a Gln----His change at position 437, which is in a domain of conserved region 2.4 that is predicted to form an alpha-helix. Gln437 would lie one turn of the alpha-helix away from Thr440, which was previously implicated in recognition of position -12. The rpoD-QH437 mutation described here lends further support to the model that region 2.4 of sigma is involved in recognition of the 5' end of the -10 hexamer. In addition, two rpoD mutations with non-specific effects on promoter recognition are described.

Amino Acid Sequence↗
PubMed1990

Modified behavioral and olfactory bulb responses to maternal odors in preweanling rats.

Rat pups acquire an attraction for maternal odors, which can vary with maternal diet. In the two experiments reported here, maternal diet was modified and both pup behavioral responses and pup olfactory bulb neural responses [( 14C]2-DG uptake) to maternal odors were examined. In experiment 1, pups were reared from birth to postnatal day 19 with either a dam fed normal rat chow or a dam fed a sucrose-based diet which suppressed her normal maternal odor. In experiment 2, pups were raised from birth to postnatal day 19 with either a dam fed the sucrose-based diet adulterated with peppermint, or the non-scented sucrose-based diet. Pups selectively expressed both a behavioral attraction and an enhanced olfactory bulb neural response to odors that they experienced in the nest.

Action Potentials↗
PubMed1990

Influence of coat color genes on seizure behavior in Mongolian gerbils.

Seizure tendencies of three separate lines of Mongolian gerbils Meriones unguiculatus carrying three different coat color alleles were investigated. These alleles were agouti (A/-), black or nonagouti (a/a), or sandy (pink-eyed dilution p/p). Each animal was stroked on the back and then placed in a novel cage for 5 min while its seizure activity was measured in terms of latency, duration, and severity (grade). The results indicate that gerbils which are homozygous recessive at the pink-eyed dilution locus (sandy) exhibit less severe and shorter seizures than others. However, gerbils which are homozygous recessive at the agouti gene locus (black) show a shorter latency to manifest seizures than the other animals. These results indicate that the genetic mechanism determining coat color in Mongolian gerbils may also influence the susceptibility of these animals to seizure arising from novel stimulation.

Animals↗
PubMed1990

Social preference of female gerbils (Meriones unguiculatus) as influenced by coat color of males.

Female gerbils (Meriones unguiculatus) of three distinct coat colors (agouti, black, and sandy or pink-eyed dilution) were tested in a Y-maze whose arms led to compartments containing unfamiliar male gerbils of varying coat colors. The stimulus animals were separated from the females by a Plexiglas door. The trials lasted for 2 min and each female was exposed to the following four combinations: two males of the same coloring as the female; one male of the same color and another of a different color from the female; both males of different color from the female. The number of crossings to the left and right arms was relayed by photocells to an IBM PC computer. The results indicate that agouti females preferred visiting the arm occupied by agouti males while those of the other coat colors showed no preference for the "wild-type" males. Instead, sandy and black female gerbils preferred to be in proximity with those of non-wild types.

Animals↗
PubMed1990

Methylprednisolone acetate does not cause inflammatory changes in the epidural space.

Few studies have examined the possible adverse effects that epidural injection of depot corticosteroid preparations may have on meningeal membranes and nervous tissue. Thirty-six healthy adult white rabbits received 0.3 ml/kg epidural injections of either lactated Ringer's solution (negative control group), 1% lidocaine containing methylprednisolone acetate (study group), or normal saline containing talc (positive control group). Animals were killed either 4 or 10 days after injection and stained sections of the spinal cord and meningeal membranes were examined by light microscopy. In all animals that received either lactated Ringer's solution or lidocaine with methylprednisolone acetate, microscopic examination of specimens taken from the L5-L6 interspace revealed no white cell infiltrates and no fibroblastic activity. All animals that received epidural injections of normal saline containing talc had marked infiltration of tissue macrophages in the epidural space. There was no thickening of the meningeal membranes or nerve roots in any animal. The complete lack of inflammatory changes and meningeal thickening demonstrated in this pilot study helps to confirm the safety of methylprednisolone acetate when injected into the epidural space.

Animals↗