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Biomedical subjects

M L Ho

Publications and source records attributed to M L Ho.

52 records · Page 3Linked to original sources
PubMed1992

Improvement of sexual behavior in aged rats by p-chlorophenylalanine and methysergide.

The effects of methysergide, a serotonin antagonist, and p-chlorophenylalanine (PCPA), a serotonin synthesis blocker on the sexual behavior of intact old male rats at 19-23 months of age and female rats at 17-18 months of age were studied. Female rats with prolonged vaginal cornification and a lordosis quotient (LQ) of less than 50%, and male rats displaying no ejaculation were selected as experimental animals. The receptivity of aged female rats, but not the approach behavior to males nor proceptivity was improved by PCPA or methysergide. The LQ of intact aged female rats in non-exit tests was improved by the i.p. administration of 50 mg/kg B.W. of PCPA 2 to 4 hours prior to the sexual behavior test or 3 mg/kg B.W. of methysergide 4 hours prior to the test. Total mount frequency and mount latency of intact aged male rats were improved by the administration of methysergide (3 mg/kg B.W.), while total mount frequency and intromission latency were improved by the administration of PCPA (20 mg/kg B.W. for 4 days). The present results together with the finding from our previous study suggest that the increase of serotonin (5-HT) activity per se plays an important role in the decline of receptivity of aged female rats and the copulatory activity of aged male rats.

Aging↗
PubMed1991

Low serum calcium and high parathyroid hormone levels in neonates fed 'humanized' cow's milk-based formula.

We previously suggested that "late" neonatal hypocalcemia is related to a low calcium-phosphorus ratio of current cow's milk-based formula compared with human milk. However, there are no longitudinal studies of ionized calcium and parathyroid hormone concentrations in neonates receiving formulas with varying Ca/P ratios. Sixty-nine term neonates were studied through 2 weeks of age, and formula-fed neonates were randomized at birth to receive formula with molar ratios of 0.9, 1.2, or 1.4. Serum phosphate concentrations on days 2 and 6 of age were higher, and ionized calcium levels lower on days 6 and 14, in formula-fed vs human milk-fed neonates. Serum intact parathyroid hormone level increased between days 2 and 6 in formula-fed neonates compared with a decrease in human milk-fed neonates. Serum parathyroid hormone level on day 6 correlated with phosphorus intake among formula-fed neonates. No differences were noted in serum mineral or hormone levels among formula-fed groups. We speculate that the lowering of serum ionized calcium concentrations in neonates fed a modern "humanized" cow's milk formula may be a factor in late neonatal hypocalcemia.

Analysis of Variance↗
PubMed1991

Vitamin B-12 status in a macrobiotic community.

Vitamin B-12 status was assessed in a group of 110 adults and 42 children from a macrobiotic community in New England. Dietary and anthropometric information also was obtained. Fifty-one percent of the adults had low concentrations of serum vitamin B-12, which inversely correlated with duration of macrobiotic diet practice. Urinary methylmalonic acid (MMA) excretion was inversely correlated with serum vitamin B-12, and 30% of adults sampled had high urinary MMA. Fifty-five percent of children had high urinary MMA, and MMA was higher in the group that consumed a macrobiotic diet during their entire lifetime. Children were relatively short in stature and weight, and decreased stature was associated with high urinary MMA. In both adults and children vitamin B-12 status was better with more consumption of dairy products or with higher tertile of reported frequencies of vitamin B-12 consumption of various animal products. Vitamin B-12 status appeared to be unrelated to consumption of several vegetarian foods.

Adult↗
PubMed1991

Changes in calcium homeostasis over the first year postpartum: effect of lactation and weaning.

There is little information on the effect of lactation on maternal mineral and calcitropic hormone status. Therefore, we prospectively compared 26 lactating women with 32 nonlactating postpartum controls over the first year postpartum. Nineteen of the 26 women breast-fed their infants for fewer than 12 months and seven breast-fed for at least 12 months. During the first 6 months postpartum, serum phosphorus and parathyroid hormone (PTH) concentrations decreased with increasing time (P = .04 and P = .003, respectively) and were higher in lactating compared with nonlactating women (P less than .001 and P = .06, respectively). Mean serum phosphorus concentrations at 1, 3, and 6 months postpartum were 4.45, 4.75, and 4.34 mg/dL, respectively, in lactating women, versus 4.01, 3.64, and 3.44 mg/dL in controls. Mean PTH concentrations were 1.58, 1.48, and 1.36 ng/mL in lactating women, compared with 1.45, 1.20, and 1.16 ng/mL, respectively, in controls. At 12 months, women who were weaning had significantly higher mean serum calcium (10.11 mg/dL) and magnesium (2.36 mg/dL) concentrations than those who had weaned (8.79 and 2.03 mg/dL, respectively) or who had never lactated (8.90 and 1.95 mg/dL, respectively). Serum phosphorus, PTH, and 1,25-dihydroxyvitamin D were similar among women who were weaning (4.02 mg/dL, 1.46 ng/mL, and 54 pg/mL, respectively) and those who had weaned (3.94 mg/dL, 1.68 ng/mL, and 55 pg/mL), and were significantly higher than concentrations in women who had never lactated (3.25 mg/dL, 0.92 ng/mL, and 39 pg/mL). Our findings during lactation and the persistent differences observed during and after weaning are consistent with bone mobilization during lactation and a recovery of bone mass during and after weaning.

Calcium↗
PubMed1990

Urinary methylmalonic acid excretion in infants fed formula or human milk.

Serum vitamin B-12 and urinary methylmalonic acid (MMA) concentrations were determined in 62 healthy infants aged 1-6 mo. Urinary MMA was inversely correlated with serum vitamin B-12 concentrations (r = -0.550, p less than 0.001); serum vitamin B-12 was higher (p less than 0.001) and urinary MMA concentrations were lower (p less than 0.001) in formula-fed infants than in infants fed human milk (from the breast). Human-milk-fed infants who had received supplemental formula had higher serum vitamin B-12 concentrations than did infants exclusively fed human milk. It is not clear whether the serum vitamin B-12 and urinary MMA concentrations in infants fed human milk reflect biochemical deficiency of vitamin B-12, and the clinical significance of these findings needs to be investigated.

Female↗
PubMed1990

Normal boron excretion levels and borates related gastroenteritis cases in Singapore.

Urinary borates calculated as boric acid were found to span 0 to 54 microgramme per ml urine for both Singaporean adults (population size: 507) and children (population size: 162). The normal dietary boron intake could account for the urinary boric acid levels observed. Of the hundred and fifty-three children who suffered from gastroenteritis in Singapore over the period from Jan to May 1989, two were found to have urinary boric acid exceeding 54 micrograms per ml urine. One of them was said to have consumed fish balls, bean curds and noodles prior to the onset of illness. These food items were among those likely to have added borates. Unfortunately, the dietary intake prior to the onset of illness of the other child was not recorded. Of the hundred and twelve adults affected by gastroenteritis in Dec 1988 in the Tiong Bahru area, one was found to have boric acid level of 117 micrograms per ml urine, indicative of added borates in the diet. The present study showed that borates related gastroenteritis incidents in Singapore over the time-period of our study at least, were few and far in between. With the on-going surveillance for the presence of added borates in both locally manufactured and imported food and the continued tight control over the importation and sale of borates, future incidents are likely to be minimal.

Adult↗
PubMed1990

A psychosocial study of high risk subjects for AIDS.

A psychosocial study of 5 high risk groups for AIDS (50 homosexuals, 50 drug addicts, 23 male to female transsexuals, 45 male patients at a sexually transmitted disease clinic, and 43 female prostitutes) and 5 matched control groups showed that the majority of the subjects were mostly single, with a secondary level of education and lived with family members. Although all had a high risk of AIDS, condom use was not prevalent. The subjects were less knowledgeable about AIDS than controls, were more anxious about getting AIDS and had a more hopeless and pessimistic outlook to life; however they appeared to be as altruistic and responsible as the controls.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Bone mineral content in black and white children 1 to 6 years of age. Early appearance of race and sex differences.

Bone mineral content was determined in 131 children, 1 to 6 years of age, in a prospectively designed cross-sectional study. Using multiple linear regression analysis to control for individual factors, bone mineral content was higher in black children compared with white children, was lower among female children compared with male children, increased with age, and increased with weight.

Absorptiometry, Photon↗
PubMed1989

Characterization of cDNAs of spliced HPV-11 E2 mRNA and other HPV mRNAs recovered via retrovirus-mediated gene transfer.

Human papillomaviruses (HPVs) are associated with hyperproliferations of cutaneous or mucosal epithelium. These viruses cannot be propagated in any cell culture system. Because cloning cDNA copies of HPV mRNAs recovered from human lesions has met with only very limited success, the characterization of HPV mRNAs has been problematic. Using the Moloney murine leukemia virus vector system (C.L. Cepko, B.E. Roberts, and R.C. Mulligan, 1984, Cell 37, 1053-1062), we have recovered cDNAs of spliced E2 mRNAs of human papillomavirus type 11 and additional mRNAs of type 11 and type 18 and determined the utilization of open reading frames (ORFs) in the DNA sequences. The recovery of cDNA copies of messages with splice sites identical to those previously described strongly suggests that the newly characterized splice donors and acceptors are also authentic. The HPV-11 E2 cDNA contains the intact E6 and E7 ORFs and the beginning of the E1 ORF in the first exon, which is then spliced from nt 847 to the second exon at nt 2622, 100 nucleotides upstream from the initiation codon for the E2 ORF. The initiation codon in the E1 ORF is followed by four additional in-frame AUG triplets and an in-frame termination codon positioned 30 nucleotides upstream from the initiation codon for the E2 protein. The authenticity of this putative E2 cDNA was shown by its ability to provide enhancer transactivating activity in chloramphenicol acetyltransferase (CAT) assays in several cell lines. A mutation in the genomic DNA at this splice acceptor site eliminates its activity, demonstrating that the splice is essential for the expression of the E2 protein. We conclude that the translation of the HPV-11 E2 protein requires internal initiation.

Base Sequence↗
PubMed1989

The hepatitis B immunization programme in Singapore.

A voluntary immunization programme to prevent perinatal transmission of hepatitis B virus (HBV) infection in Singapore was implemented on 1 October 1985 as an integral component of the national childhood immunization programme. Up to April 1988, a total of 68,845 mothers who attended government maternal and child health clinics were screened for the disease. Of these, 2432 (3.5%) were positive for hepatitis B surface antigen (HBsAg) and 904 (1.3%) for hepatitis B e antigen (HBeAg). Virtually all the babies born to carrier mothers completed the full immunization schedule; and in addition, those of HBeAg-positive mothers were given a dose of hepatitis B immunoglobulin at birth. The hepatitis B immunization programme was extended on 1 September 1987 to cover all newborns. About 90% of the 15,943 babies delivered in government institutions from September 1987 to April 1988 were immunized at birth, with the subsequent doses being administered at maternal and child health clinics at 4-6 weeks and 5 months later. More than 85% of the children given the full course of plasma-derived and yeast-derived hepatitis B vaccine from birth continued to have protective antibody to HBV two years after immunization. The programme is being closely monitored to assess the duration of immunity and the need for booster doses, while seronegative adults are also being encouraged to be vaccinated.

Adolescent↗
PubMed1984

Production and characterization of monoclonal antibodies to Mycobacterium tuberculosis, M. bovis (BCG) and M. leprae.

Thirty-two monoclonal antibodies (MoAb) to Mycobacterium tuberculosis H37Rv, M. bovis BCG and M. leprae were produced. The spleen cells of BALB/c mice immunized with sonicated or intact bacilli were fused with Sp2/0-Ag-14 myeloma cells. Many more antibody producing hybridomas were found when M. tuberculosis, rather than M. leprae, was used as the immunogen. The MoAb were characterized by an enzyme immunoassay and immunofluorescence on 16 mycobacterial species. The sodium dodecylsulphate polyacrylamide gel electrophoresis immunoperoxidase assay was used to determine the molecular weight of the antigens detected by the MoAb. Antigens of high, low and intermediate molecular weight were found. Some of the antigens were proteinaceous, others of a glycolipid nature. The immunofluorescence assay proved to be essential for the selection of MoAb since some MoAb reacted only in this assay and not in the enzyme immunoassay. The most specific clones were found in the fusions with spleen cells of mice immunized with intact rather than sonicated bacteria. One MoAb (F29-29) reacted only with M. tuberculosis H37Rv; one (F41-3) only with M. leprae and another (F29-45) reacted with M. tuberculosis and M. gastrii. Several MoAb only reacted with three mycobacterial species: M. tuberculosis, M. kansasii and M. gastrii. Others showed unique patterns of reactivity by enzyme immuno- and immunofluorescence assay. The potential use of the MoAb for the identification of mycobacteria and mycobacterial antigens is discussed.

Animals↗
PubMed1981

Serotoninergic mechanisms of the hypothermia induced by clerodenron fragrans (Ventenaceae) in the rat.

The effects of the Chinese herb Chou-Mou-Li, clerodenron fragrans (Ventenaceae) on metabolic, respiratory and vasomotor activities as well as body temperature were assessed in conscious rats at three different ambient temperatures (Ta) of 8, 22 and 30 degrees C. Intraperitoneal administration of Chou-Mou-li produced dose-dependent hypothermia in rats at both 8 and 22 degrees C Ta- At 8 degrees C Ta the hypothermia in response to Chou-Mou-Li was due to decreased metabolism, while at 22 degrees C Ta the hypothermia was due to both decreased metabolism and cutaneous vasodilatation. There was no change in respiratory evaporative heat loss. Furthermore, the hypothermia induced by Chou-Mou-Li was greatly antagonized by pretreatment of animals with p-chlorophenylalanine (a selective depletor of brain serotonin), but not by either atropine sulfate (a selective blocker of cholinergic receptors), regitine (a selective blocker of alpha-adrenergic receptors) or DL-propranolol (a selective blocker of beta-adrenergic receptors). However, at 30 degrees C Ta, systemic administration of Chou-Mou-Li produced no change in rectal temperature or other thermoregulatory responses. On the other hand, direct administration of serotonin into the lateral cerebral ventricle of conscious rats also produced dose-dependent hypothermia at 8 and 22 degrees C Ta. Again, the hypothermia in response to serotonin was due to decreased metabolism at 8 degrees C Ta and was due to both decreased metabolism and cutaneous vasodilatation at 22 degrees C Ta. At 30 degrees C Ta administration of serotonin also produced no change in thermoregulatory functions. The data indicate that Chou-Mou-Li produces hypothermia by increasing sensible heat loss and decreasing metabolic heat production, probably via the release of endogenous serotonin within brain.

Animals↗
PubMedDate not supplied

Production of monoclonal antibodies against Mycobacterium leprae and armadillo-derived mycobacteria.

Six monoclonal antibodies to Mycobacterium leprae and armadillo-derived mycobacteria were produced. The monoclonal antibodies were characterized by an immunofluorescence assay using 22 mycobacterial strains. One monoclonal antibody, F47-21-3, reacted only with M. leprae; two, F45-9 and F45-15, reacted only with two armadillo-derived mycobacterial strains. These six monoclonal antibodies can be used for the identification of M. leprae and armadillo-derived mycobacteria.

Animals↗
PubMedDate not supplied

Factors associated with sexually transmitted diseases among prostitutes in Singapore.

From June to December 1990, 806 prostitutes registered with the STD programme in Singapore for regular screening for sexually transmitted diseases (STD) were investigated for factors associated with STD incidence in the preceding year. The majority were foreigners (92.7% Malaysians and 3.1% Thais). Anal sex (0.4%) and intravenous drug use (0.9%) were rare. The overall STD incidence rate was 47.7 per 100. None was human immunodeficiency virus (HIV) positive. The crude and age-adjusted risk of STD was found to increase significantly with client load. An inverse relationship between condom use and STD risk was also observed. Mean condom use among clients was reported as 56.1% for spontaneous use and estimated as 75.4% following negotiation for condom use by prostitutes. Although the prostitutes negotiated for condom use with majority of the clients (85.5%) who did not use condoms spontaneously, they were successful with only about half of them (54.4%). Health education should be targeted at clients on the protective effects of condom use and at the prostitutes on skills in negotiating condom use.

Adult↗
PubMedDate not supplied

Relationship of serum lactate dehydrogenase, creatine kinase, aspartate aminotransferase concentrations and severe intraventricular hemorrhage/leukomalacia in very low birth body weight preterm neonates.

Estimations of serum enzyme values are widely employed as valuable diagnostic aids in diseases. Most commonly employed enzymes include Aspartate aminotransferase (AST), Lactate dehydrogenase (LDH), and Creatine kinase (CK). The study was designed to determine the relationship of elevated postnatal serum LDH, CK, and AST concentrations within the first day of life and the risk of suffering severe intraventricular hemorrhage (IVH) and/or periventricular leukomalacia (PVL) in VLBW preterm newborns. 81 preterm neonates whose birth body weight < 1500 gm were enrolled. Serums were obtained for measurement within the first postnatal day. Cranial ultrasound scans were performed twice per week after birth until their body weight was above 2300 gm or postconceptional age above 40 weeks. Significant difference was noted in serum LDH and CK concentrations in severe IVH/PVL infants (p < 0.05). No difference was found in serum AST values. Compared with the cut-off values of 1933 IU/L of LDH concentration and 652 IU/L of CK, the predictive values revealed a sensitivity, specificity, negative predictive value and positive predictive value of 76.9%, 89.7%, 95.3% and 58.8%, respectively. In conclusion, higher serum LDH and/or CK concentrations within the first day of life were associated with risk for development of severe IVH/PVL.

Aspartate Aminotransferases↗