Search PubMed⌕ Search

Biomedical subjects

R Gold

Publications and source records attributed to R Gold.

At least 271 records · Page 15Linked to original sources
PubMed1979

Diffusion of ions in myelinated nerve fibers.

The diffusion of ions towards or away from the inner side of the nodal membrane in preparations, the cut ends of which are placed in various media, was investigated. The ion concentration changes were calculated by numerical solution of the unidimensional electrodiffusion equation under a variety of media compositions, axoplasmic diffusion coefficients, and internal anionic compositions. The potassium and cesium ion diffusion along the axon towards the node was determined experimentally by two different electrophysiological methods. On the basis of comparison between the experimental data and the computational predictions the axoplasmic potassium ion diffusion coefficient was determined to be almost equal to that in free aqueous solution, while that of cesium ion was close to one half of that in aqueous solution. Utilizing the values of diffusion parameters thus determined, we solved the electrodiffusion equation for a number of common experimental procedures. We found that in short fibers, cut 0.1-0.2 cm at each side of the node, the concentration approached values close to the new steady-state values within 5-30 min. In long fibers (over 1 cm long) steady-state concentrations were obtained only after a few hours. Under some conditions the internal concentrations transiently overshot the steady-state values. The diffusion potentials generated in the system were also evaluated. The ion concentration changes and generation of diffusion potential cannot be prevented by using side pools with cation content identical to that of the axoplasm.

Animals↗
PubMed1979

Polysaccharide meningococcal vaccines--current status.

Two separate periods of intensive research, with a 25-year hiatus after the advent of the sulfonamides, have resulted in two good, but imperfect, antimeningococcal vaccines--against serogroups A and C. Neither is recommended for routine use, but both have been effective in halting epidemics. Lack of an effective group B immunogen remains the major obstacle to the control of meningococcal disease.

Adult↗
PubMed1979

Kinetics of antibody production to group A and group C meningococcal polysaccharide vaccines administered during the first six years of life: prospects for routine immunization of infants and children.

A cohort of infants, previously immunized once or twice between three and 12 months of age with vaccines containing polysaccharide of groups A and C Neisseria meningitidis, received boosters at two and five and one-half years of age with bivalent A/C vaccine. Antibody concentrations were measured by a radioactive antigen-binding assay. Concentrations of antibody to groups A and C N. meningitidis were 5.59 and 2.86 microgram/ml, respectively, by four years of age. After booster immunization at five and one-half years of age, concentrations of antibody to groups A and C N. meningitidis increased to 15.67 and 7.59 microgram/ml, respectively. Protective levels of antibody to group A meningococci may be achievable throughout early childhood by routine immunization with the A vaccine. Although the group C vaccine is effective in control of epidemics, the rapid decline in the concentration of antibody to group C meningococci following immunization of young children suggests that protection may not be long-lasting.

Aging↗
PubMed1979

Meningococcal group Y pneumonia in an adolescent female.

Neisseria meningitidis group Y has been considered to be an uncommon pathogen. Meningococcal group Y disease has recently been reported with increased frequency in military training camps coincident with the routine use of meningococcal group C vaccine. Pneumonia produced by the group Y organism may mimic disease caused by common respiratory tract pathogens, and isolation by routine methods may be difficult. A 16-year-old asthmatic female developed lobar pneumonia secondary to N meningitidis group Y while on alternate day steroids. We speculate that neither steroid therapy nor an isolated serum IgA deficiency in the presence of secretory IgA discovered after her recovery predisposed her to sinopulmonary disease. The true incidence of group Y disease is unknown. Awareness of its potential pathogenicity may have clinical significance with the availability of a group Y vaccine.

Adolescent↗
PubMed1978

Carriage of Neisseria meningitidis and Neisseria lactamica in infants and children.

Asymptomatic carriage of Neisseria meningitidis and Neisseria lactamica was studied in a total of 2,969 healthy infants and children in Danbury, Conn., between October 1971 and June 1975. The prevalence of N. meningitidis averaged 0.71% during the first four years of life and increased to 5.4% by 14--17 years. Rates of carriage of N. lactamica increased from 3.8% in three-month-old infants to a peak of 21.0% at 18 months and then declined to 1.8% by 14--17 years of age. Of the children who acquired N. lactamica, 66% developed fourfold or greater rises in titers of IgG antibody to groups A, B, and/or C meningococci as determined by immunofluorescence compared with only 5% of control children. Of new carriers of N. lactamica, 40% developed increased titers of bactericidal antibody to groups A, B, and/or C meningococci as compared with 7% of noncarriers. Carriage of N. lactamica may assist in the development of natural immunity to N. meningitidis by induction of cross-reactive antibodies.

Aging↗
PubMed1978

Antibody responses of human infants to three doses of group A Neisseria meningitidis polysaccharide vaccine administered at two, four, and six months of age.

Infants were immunized with group A Neisseria meningitidis polysaccharide vaccine at two, four, and six months of age. Two lots of group A vaccine that differed in molecular weight were used; lot no. 1980A was of significantly larger molecular size than lot no. A-7. No significant adverse reactions occurred. The geometric mean concentration of serum antibody to group A N. meningitidis one month after the third dose of lot no. 1980A was 0.89 microgram/ml, nearly twice the concentration induced by lot no. A-7 (0.48 microgram/ml). When the infants were 12 months of age, concentrations of antibody in both groups had declined to similar levels, which were still greater than the mean concentration of antibody in unimmunized children. By 18 months of age, the antibody levels of immunized and unimmunized infants were the same. The three-dose schedule resulted in significantly lower concentrations of antibody than previously studied schedules of two doses given three to four months apart.

Age Factors↗
PubMed1977

Evaluation of a two-dose regimen of influenza A/New Jersey/76 subunit virus vaccine in three- to 10-year-old children.

Fifty-one Caucasian, middle-class children (aged three to 10 years) from the suburbs of Hartford, Connecticut, were immunized with two subcutaneous doses each of 200 chick cell-agglutinating units of influenza A/New Jersey/76 subunit virus vaccine/0.5 ml. The reactivity of the vaccine was negligible, and there was no increase in reactivity with a second dose. Administration of a single dose resulted in seroconversion in one-third of the subjects. Two weeks following the second dose, 84% of the children had reciprocal titers of hemagglutination-inhibiting antibody of greater than or equal to 10, and the geometric mean titer was 51. There was no significant difference in antibody response according to age. We concluded that inoculation of two doses of subunit virus vaccine is a safe and effective means of inducing a significant antibody response. The levels of antibody required for protection and for duration of antibody response are not known.

Antibodies, Viral↗
PubMed1977

Persistence of antibody following immunization of children with groups A and C meningococcal polysaccharide vaccines.

Persistence of antibody following immunization with groups A and C meningococcal polysaccharides was studied in two groups of children. Cohort 1 (20 children, 2 to 11 years of age) received two doses of A vaccine three years apart; cohort 2 (1,345 children, 6 to 8 years of age) received A or C vaccine initially and the heterologous vaccine one year later. No significant reactions were observed. Geometric mean anti-A concentrations one month after primary and booster immunization in cohort 1 were 8.77 and 13.08 microgram/ml, respectively. Mean anti-A concentration declined 32% one year after booster immunization, but then stabilized. Mean anti-A and anti-C concentrations in cohort 2 were 9.35 and 9.12 microgram/ml, respectively, one month after primary immunization. Mean anti-A concentration declined to 5.54 and 3.62 microgram/ml while anti-C levels fell to 2.35 and 1.47 microgram/ml one and four years after immunization. The proportion of children in cohort 2 with greater than or equal to 2.0 microgram/ml of anti-A and anti-C four years after immunization were 80% and 40%, respectively. An antibody concentration greater than or equal to 2.0 microgram/ml has been associated with protection against meningococcal disease. The results suggest that routine immunization of young infants with group A vaccine may result in long-lasting immunity. The usefulness of the presently available group C vaccine appears to be limited to the control of epidemics.

Antibodies, Bacterial↗
PubMed1976

Conformational relevance of the beta6Glu replaced by Val mutation in the beta subunits and in the beta(1-55) and beta(1-30) peptides of hemoglobin S.

The beta subunits of hemoglobin S showed a higher ellipticity than the beta subunits of the hemoglobin A, both in the Soret and near-ultraviolet regions. The apoderivatives of the beta subunits of hemoglobin S showed a lower helical content and a larger amount of beta conformation than the apoderivatives of the beta subunits of hemoglobin A. The beta(1-55) peptides and beta(1-30) peptides from the beta subunits of hemoglobin A and S have been separated and analyzed. The betaS(1-55) peptide showed a higher content of beta conformation and lower amount of alpha helix when compared to the betaA(1-55) peptide. This difference was present also in different concentrations of methanol. The apoderivative from the beta subunits of hemoglobin S and the betaS(1-55) peptide aggregated with increasing ionic strength. The CD measurement showed that their secondary structure did not change upon a 10-fold dilution of the sample. Very little secondary structure was present in the betaS(1-30) peptide, and the CD spectrum was very similar to that of the betaA(1-30) peptide. No significant difference in aggregation was found between the betaS(1-30) and betaA(1-30) peptides.

Amino Acid Sequence↗
PubMed1976

Clinical and radiological survey of the incidence of osteoarthrosis among obese patients.

Twenty-five grossly obese males were investigated for evidence of osteoarthrosis. A roentgenological survey of multiple joints obtained from 22 of these patients showed few significant degenerative changes. 6 patients (20%) had previously incurred traumatic rents in their menisci necessitating meniscectomy. Our results refute previous claims that obesity is a factor in the genesis of osteoarthrosis but do indicate that obese individuals are more predisposed to traumatic injury of the knee.

Adult↗
PubMed1976

The pathology of the joint tissues and its clinical relevance in prosthesis failure.

Thirty-four hip and knee total arthroplasty failures due to infection, loosening, intractable pain and dislocation were examined for synovial and capsular tissue debris. Simiquantitative assessments were made for metal polyethylene, acrylic and cellular debris and inflammation. The most important finding was that in the amounts normally shed into joints, debris particles do not appear to stimulate a polymorphonuclear response. The magnitude of this response correlates best with clinical and/or bacteriological evidence of infection. The quantity of acrylic particles could be correlated with clinical evidence of loosening. Since the correlation between infection and polymorphonuclear leukocytes, debris particles, and the reasons for failure is high, frozen section may aid the surgeon in determining the methods and timing of revision operations.

Acrylates↗