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Biomedical subjects

H W Hsu

Publications and source records attributed to H W Hsu.

At least 37 records · Page 2Linked to original sources
PubMed1994

Neonatal serologic screening and early treatment for congenital Toxoplasma gondii infection. The New England Regional Toxoplasma Working Group.

BACKGROUND: Most infants with congenital Toxoplasma gondii infection have no symptoms at birth, but many will have retinal disease or neurologic abnormalities later in life. Early detection and treatment of congenital toxoplasmosis may reduce these sequelae. METHODS: In Massachusetts since January 1986, and in New Hampshire since July 1988, newborns have been screened for intrauterine infection with T. gondii by means of an IgM capture immunoassay of blood specimens routinely collected for screening for metabolic disorders. Congenital infection is confirmed by assays for specific IgG and IgM antibodies in serum from infants and their mothers. For this study, infants with serologic evidence of infection underwent extensive clinical evaluation and received one year of treatment. RESULTS: Through June 1992, 100 of 635,000 infants tested had positive screening tests. Congenital infection was confirmed in 52 infants, 50 of whom were identified only through neonatal screening and not through initial clinical examination. However, after the serologic results became available, more detailed examinations revealed abnormalities of either the central nervous system or the retina in 19 of 48 infants evaluated (40 percent). After treatment, only 1 of 46 children had a neurologic deficit (hemiplegia attributable to a cerebral lesion present at birth). Thirty-nine treated children had follow-up ophthalmologic examinations when one to six years old; four (10 percent) had eye lesions that may have developed postnatally (a macular lesion in one child and minor retinal scars in three). CONCLUSIONS: Routine neonatal screening for toxoplasmosis identifies congenital infections that are subclinical, and early treatment may reduce the severe long-term sequelae.

Antibodies, Protozoan↗
PubMed1994

Inaccurate noninvasive mitral valve area calculation during pregnancy.

OBJECTIVE: To compare two different Doppler echocardiographic techniques for the assessment of the transmitral area in pregnant patients with native mitral valve stenosis or prosthetic mitral valves. METHODS: Eight consecutive gravid women with prosthetic mitral valves or obstructive native mitral valve disease were evaluated using both the pressure half-time and the continuity equation Doppler echocardiographic methods. Heart rate, cardiac output, and transmitral valve gradient and area were calculated. These studies were repeated postpartum in five women. Differences between the two methods were assessed by characterizing the absolute differences between the mean and standard deviation and by paired t tests. Linear regression analysis was also applied. RESULTS: For the five women who also had postpartum studies, antepartum data were similar to those of the full set of eight patients. Postpartum heart rate, cardiac output, and transvalvular gradient were lower than antepartum measurements. Calculations using the continuity equation yielded comparable antepartum and postpartum estimates of transmitral areas (1.31 +/- 0.41 versus 1.32 +/- 0.44 cm2, respectively, r = 0.96). These estimates were also consistent with the initial clinical presentation. In contrast, antepartum transmitral valve areas calculated using the pressure half-time technique (2.67 +/- 0.61 cm2) were markedly higher than postpartum (1.94 +/- 0.58 cm2). The correlation between the estimates of antepartum valve area given by the two methods was not statistically significant (r = 0.02). In contrast, there was excellent postpartum correlation of transmitral area between the methods (r = 0.99), despite a significant difference (P < .001) in the transmitral area calculated with each technique. CONCLUSIONS: The results indicate that Doppler echocardiographic estimates of the transvalvular area using the continuity equation technique during pregnancy are valid. In contrast, estimates of area using the pressure half-time technique in pregnant patients are dubious and could result in life-threatening consequences.

Adult↗
PubMed1994

Propofol modifies recovery from isoflurane-nitrous oxide anesthesia.

A randomized, prospective study was performed to evaluate the hemodynamic changes and recovery characteristics in 60 ASA physical status class I-II unpremedicated patients undergoing gynecological laparotomies with either isoflurane anesthesia only (ISO group) or isoflurane anesthesia followed by propofol infusion (ISO-PRO group). All patients received isoflurane 0.5-1.5% and nitrous oxide (N2O) 66% in oxygen after tracheal intubation. ISO-PRO group (n = 30) received 6 mg kg-1 hr-1 propofol infusion in substitution for isoflurane 25 minutes before the end of surgery. Propofol in ISO-PRO group and isoflurane in ISO group (n = 30) were discontinued 5 minutes before the end of surgery. In both groups, N2O was administered throughout the operation until skin was closed. Hemodynamic measurements were similar between the two groups except at extubation when heart rate and blood pressure were lower in ISO-PRO group. The maximal blood pressure was also lower in ISO-PRO group. In ISO-PRO group, the time required to responsiveness to verbal commands and to orientation were significantly shorter. ISO-PRO group had better Steward's score on arrival at the recovery room and was earlier to get a full score of six. The two groups experienced similar rates of emesis and excitement either two hours or 24 hours postoperatively. We conclude that in relatively long intra-abdominal operations, replacement of isoflurane by propofol infusion 25 minutes before the end of surgery may provide stable maintenance of anesthesia and a faster recovery.

Adult↗
PubMed1993

Identifying human immunodeficiency virus infection at birth: application of polymerase chain reaction to Guthrie cards.

Guthrie cards containing dried blood spots from 67 children now known to be infected with human immunodeficiency virus (HIV) and 63 children now classified as having had seroreversion were retrieved from the newborn infant archives from 1986 through 1991 to determine whether the polymerase chain reaction (PCR) could predict the infection at birth. The PCR assays operating at a sensitivity capable of detecting 2 to 10 copies of HIV proviral DNA per microgram were able to detect HIV proviral DNA in 52% (35/67) of the infected neonatal blood specimens. Longer storage times did not decrease PCR positivity rates, an advantage over assays for HIV antibody. Children whose clinical progression has been aggressive had high rates of PCR positivity in neonatal specimens, 50% (7/14) in those with low CD4 cell counts during the first year of life, 71% (10/14) in those with Pneumocystis pneumonia or disseminated cytomegalovirus infection by age 1 year, 62% (18/29) in those with onset of acquired immunodeficiency syndrome by 18 months, and 66% (14/21) in those who died of the disease by 36 months of age. No evidence of HIV proviral DNA was found in any of the 63 specimens from children with seroreversion. We conclude that PCR, using routinely available dried blood spots from neonates, has applications in early diagnosis and in epidemiologic projections going beyond current seroprevalence studies.

AIDS Serodiagnosis↗
PubMed1992

Newborn screening for congenital Toxoplasma infection: five years experience in Massachusetts, USA.

Since 1986, all Massachusetts newborn filter paper blood specimens, and some from New Hampshire, have been screened for the presence of IgM antibodies to Toxoplasma gondii using an enzyme-linked IgM capture assay. Among approximately 530,000 infants screened, 40 had serologically confirmed congenital toxoplasma infection, and 4 additional infants had borderline serologies, for an overall identification and treatment rate of 1:12,000. False positive results from the newborn's filter paper specimen occurred in 22 infants (1/24,000); these were clarified by tests for IgM and IgG in serum specimens obtained 2-3 weeks later from the infant and mother. The screening program would have failed to detect 3 infants with severe infection who were diagnosed on clinical grounds prenatally or at birth and lacked IgM. No infants with a later diagnosis of congenital toxoplasmosis that was missed by screening are known to our statewide network of pediatric infectious disease consultants. Follow-up studies are in progress to evaluate more completely the sensitivity of the IgM assay in newborns and the efficacy of treatment.

Antibodies, Protozoan↗
PubMed1992

[Clinical analysis of adenocarcinoma of the stomach in patients with duodenal ulcer].

In 332 patients of adenocarcinoma of the stomach and 7095 patients with duodenal ulcer collected in 5-year period, 21 cases were found to have both disease entities. With regard to clinical manifestations, gross morphology, microscopic differentiation and management of adenocarcinoma of the stomach, the patients with duodenal ulcer showed no significant difference from those without duodenal ulcer. The activities of the duodenal ulcers could be in acute active stage or present as chronic scar only. The ulcer history varied from several years to more than 15 years. We concluded that the frequency of adenocarcinoma of the stomach developed in patients with duodenal ulcer is not so rare, presentation of epigastric discomfort or signs of UGI bleeding in patients with duodenal ulcer history not always indicated recurrence of ulcer disease.

Adenocarcinoma↗
PubMed1992

Biologic, foster, and adoptive parents: care givers of children exposed perinatally to human immunodeficiency virus in the United States. The Pediatric Spectrum of Disease Clinical Consortium.

Children born to human immunodeficiency virus (HIV)-infected mothers often do not live with a biologic parent because of drug use, illness, or death of the mother. Public health officials need to know the number and proportion of children who will require care by someone other than a biologic parent (alternative care giver). The Pediatric Spectrum of Disease project, conducted in six different geographic regions in the United States, assesses issues specific to HIV in children. Among the information being collected in this study are data regarding the primary care giver. Of 1683 children born to HIV-infected mothers and enrolled through 1990, 55% (937) were living with a biologic parent, 10% (169) with another relative, 28% (455) were in foster care, 3% (55) had been adopted, and 4% (67) lived in group settings or with other care givers. In all locations and for all racial/ethnic groups, children of mothers who used intravenous drugs were more likely to be living with an alternative care giver than were children of mothers who had not used intravenous drugs (odds ratio 4.15). However, there were striking variations by study location (odds ratio range 1.4 to 7.2). The data suggest that maternal drug use may be the most important factor determining whether a child lives with a biologic parent and that there are also regional differences in alternative care placement.

Adoption↗
PubMed1992

Perinatally acquired human immunodeficiency virus infection: extent of clinical recognition in a population-based cohort. Massachusetts Pediatric HIV Surveillance Working Group.

To evaluate factors that may affect the timely diagnosis of children with human immunodeficiency virus (HIV) infection, we compared data derived from two population-based pediatric HIV studies. Data from anonymous newborn HIV serosurveys were used to estimate the number of children born to HIV-seropositive mothers. A statewide active surveillance project determined the number of HIV-exposed children who had been clinically recognized. Of 88,732 Massachusetts newborn specimens tested anonymously for HIV antibodies during a 12-month period (November, 1987, to October, 1988), 223 were positive. As of October, 1991, 78 of these children (35%) had been identified by a statewide network of infectious disease physicians. HIV-exposed children born in inner city hospitals were more likely to have come to medical attention than those born in suburban hospitals (47% vs. 17%). Among the 29 children with confirmed HIV infection (13% of 223), the initial evaluation for HIV occurred at an earlier age among children born in inner city hospitals than among children born in other areas. HIV testing practices that rely heavily on risk assessment may result in delayed diagnosis of HIV infection in children whose mothers are not perceived to be at risk.

AIDS Serodiagnosis↗
PubMed1989

Power spectrum analysis of myometrial electromyogram and intrauterine pressure changes in the pregnant rhesus monkey in late gestation.

Various methods have been used to quantify myometrial activity in the pregnant rhesus monkey during the last third of gestation. A precise definition of activity must retain the characteristics of epoch duration, amplitude, and the repetitive frequencies of active epochs. We used Fast Fourier Transform and power spectrum analysis to determine whether the patterns of myometrial contractility consist predominantly of contractions or contractures. This analysis allows quantification of activity represented by each of these patterns of activity. We applied these methods to myometrial electromyogram and intrauterine pressure recordings in pregnant rhesus monkeys to characterize the changes in myometrial activity that occur after surgery, after intravenous indomethacin administration, and when food is withdrawn for 48 hours. We conclude that changes in the frequency pattern of myometrial activity provide important information in relation to labor and delivery contractions.

Animals↗
PubMed1985

Point mutations in the P30 domain of the gag gene of Moloney murine leukemia virus.

A series of point mutations in the P30 domain of the Moloney murine leukemia virus gag gene was generated by bisulfite treatment of heteroduplex DNAs containing a single-stranded region in the gag gene. One virus bearing such a mutation exhibited a coordinate defect in gag and pol function, and was similar to previously described deletion mutants with alterations in this gene. One mutant virus displayed a different phenotype: it could assemble virion particles and provide pol function, but the particles were defective in the early stages of infection. The continued concordance of the mutants' failure or ability to both assemble virions and provide pol lends further support to the proposal that similar parts of the gag gene are required for these two processes.

Amino Acid Sequence↗
PubMed1983

Immobilization of Clostridium thermocellum cells on bituminous coal particles.

The immobilization isotherms of Clostridium thermocellum cells on bituminous coal particles of approximately 0.15- to 0.18-mm diameter were experimentally measured at 60, 45, and 30 degrees C with a pH value of 7.0 and with pH values of 6.0 and 5.0 at 60 degrees C. The immobilization data were correlated into Langmuir forms and their characteristic coefficients were obtained. A method to obtain thermodynamic quantities delta G, delta H, and delta S for the immobilization is also demonstrated.

Adsorption↗
PubMed1981

Three different human tumor cell lines contain different oncogenes.

We have obtained foci of transformed mouse cells after transfection of human DNA from colon and bladder carcinoma cell lines and a promyelocytic leukemia cell line. These foci can be shown to contain a large number of human DNA sequences by use of highly repetitive human DNA sequence probes. Cell DNA from primary foci can be used in a subsequent cycle of transfection resulting in secondary foci that contain relatively little human DNA. Secondary foci appear to contain only the human sequences proximal to those responsible for the transformed phenotype. A set of characteristic DNA restriction fragments is found in common among secondary foci derived from each tumor cell line DNA. Comparison of the common DNA fragments found in secondary foci derived from three different human tumor cell lines indicates that these three cell lines contain three different transforming genes.

Animals↗
PubMed1978

Immobilization of immunoglobulins on polystyrene latex beads: characterization by density gradient centrifugation.

Isopycnic banding by density gradient centrifugation was used to measure density changes in complexes formed by the immobilization of each of four different immunoglobulins (IgG) (bovine, dog, rabbit, and sheep) on polystyrene latex beads (0.109 +/- 0.0025 micrometer diameter). Subtractive measurements of density changes allowed calculation of the mass of immobilized IgG under varying experimental conditions. The immobilization data were correlated with adsorption isotherms which incorporated charge repulsion forces. The effects of pH and NaCl concentration on the immobilization were studied for the latex-bovine IgG system. It was found that the mass of immobilized immunoglobulins was increased from 10 to 20% by removing the IgG from its isoelectric range.

Animals↗
PubMed1978

Interaction of antibody with antigen immobilized on polystyrene latex beads: characterization by density gradient centrifugation.

Isopycnic banding by density gradient centrifugation was used to measure density changes in complexes formed by the interaction between antigen and antibody immobilized on polystyrene latex beads (diameter, 0.109 +/- 0.0025 micron). Measurements of density changes allowed calculation of the interacting masses under the given experimental conditions. Interaction equilibrium constants and free energy change for two sets of reactions, bovine IgG and anti-bovine IgG (rabbit) IgG and rabbit IgG and anti-rabbit IgG (goat) IgG systems, were calculated from isopycnic banding density gradient centrifugation runs. The procedure demonstrates a new method of obtaining quantitative information on antigen-antibody interactions.

Animals↗
PubMed1976

Amino acid metabolism of myeloma cells in culture.

The growth of myeloma cells in Leibovitz medium supplemented with 20% serum was limited by the depletion of glutamine. A simple modification of the Leibovitz medium by increasing the concentrations of glutamine, lysine, isoleucine, leucine, sodium pyruvate, galactose, and vitamins resulted in over 100% increase in cell growth yield. The total myeloma protein produced by the cells was increased by approximately 90% in modified Leibovitz media. Analysis of spent culture media for 19 amino acids showed that the concentrations of 8 amino acids were reduced; those of 5 amino acids were increased and the other 6 did not change significantly.

Amino Acids↗