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Biomedical subjects

M L Ho

Publications and source records attributed to M L Ho.

At least 37 records · Page 2Linked to original sources
PubMed1996

Normal serum indices of bone collagen biosynthesis and degradation in small for gestational age infants.

Serum carboxyterminal propeptide of type I procollagen (PICP) and cross-linked carboxyterminal telopeptide of type I collagen (ICTP), new markers of bone collagen type I biosynthesis and degradation, have not been studied in small for gestational age (SGA) infants. In an earlier study, we found a lower bone mineral content (BMC) and decreased serum osteocalcin in SGA than in appropriate for gestational age (AGA) infants, supporting the thesis that decreased fetal bone formation is a cause of lower BMC in SGA. In view of the role of insulin-like growth factor-I (IGF-I) in the regulation of collagen type I synthesis and degradation, and low serum IGF-I concentrations in SGA infants, we hypothesized that serum PICP would be lower and serum ICTP would be higher in SGA than in AGA infants, reflecting decreased bone collagen type I biosynthesis or enhancement of bone collagen type I degradation in SGA. We studied 19 term SGA and 38 term AGA infants that were matched specifically 1:2 by gestation and birth month. There were no differences between SGA and AGA infants in serum PICP nor ICTP concentrations. Serum ICTP was correlated with osteocalcin and with PICP in SGA infants but not in AGA infants. Thus, serum biochemical indices of bone collagen type I biosynthesis and degradation in term SGA infants are similar to those in term AGA infants. These findings are not consistent with the thesis of altered fetal bone collagen type I biosynthesis or degradation in SGA. We suggest that the reduced bone mineral content in SGA infants is predominantly related to a lower supply of minerals rather than defective regulation of bone collagen type I metabolism.

Biomarkers↗
PubMed1996

Effects of compressive loading on articular cartilage repair of knee joint in rats.

Effects of compressive loading on articular cartilage repair was studied. Thirty adolescent Long-Evans rats were used as experiment animals. A full-thickness defect of cartilage was created by drilling with a k-wire, 1.2 mm in diameter, into the weight bearing area of medial femoral condyle of each of bilateral knee joints. Free movement was permitted postoperatively. One leg of each rat received normal weight bearing on knee joint as experiment leg. The contralateral leg was used as the control. The control legs were paw resected to avoid weight bearing on joint cartilages but this did not interfere with the motion of knee joints. The articular cartilage repair was estimated by macroscopic examination and microscopic examination 6 weeks after surgery. Scoring systems were used to evaluate the quantity of repaired tissue in macroscopic examination and the quality of repaired tissue in microscopic examination. The differences of articular cartilage repair affected by compressive loading was analyzed statistically by paired t-test. We concluded that the effects of compressive loading on cartilage repair was to accelerate the metaplasia of repair tissue into hyaline cartilage but not to increase the quantity of repaired tissue.

Animals↗
PubMed1995

[Effect of pinealectomy on N-methyl-D-aspartate-facilitated receptivity in female rats].

The purpose of this study was to examine the effect of pinealectomy and the possible mechanism of the pineal gland on N-methyl-D-aspartate (NMDA)-associated receptivity in female rats. Monosodium L-glutamate (MSG) was used as a neurotoxin to induce hypogonadal status. Long-Evans rats were divided into four groups: (1) control (C), (2) pinealectomized (Px), (3) MSG-treated (MSG) and (4) pinealectomized MSG-treated (Px-MSG). Two injections of MSG were administered on the first and the third days postnatally with a dose of 4 mg/g body weight. Pinealectomy was performed at six weeks of age. In the first part of the experiment, all four groups of rats were ovariectomized at 3.5 months and implanted subcutaneously with a 2mm silastic capsule filled with 20% estradiol benzoate (EB). One week later, the sexual receptivity was estimated by lordosis quotient (LQ) before and ten minutes after 20 mg/kg B.W. NMDA administration. The result shows that NMDA caused a remarkable increase of LQ in control rats, but no significant effect on MSG-treated rats. There was no significant difference between control and Px rats before NMDA administration, but Px rats exhibited higher LQ than control rats after NMDA treatment. In the second part of the experiment, the effect of pinealectomy on releasability of LHRH neurons was examined indirectly by NMDA-evoked LH secretion. The dosage and sampling schedule were chosen by the dose-response and time course of LH response to NMDA, respectively. Serum samples were collected before and ten minutes after NMDA administration. Serum concentration of LH was measured by radioimmunoassay.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Antiinflammatory drug effects on bone repair and remodeling in rabbits.

Ketorolac and methylprednisolone effects on bone repair were studied. Demineralized bone matrix was used to graft the defects of rabbits' ulnae. Twenty-seven rabbits were divided into 4 groups: Group A (control group; no drug treatment), Group B (treated with ketorolac 2 mg/kg body weight daily), Group C (treated with ketorolac 4 mg/kg body weight daily), and Group D (treated with methylprednisolone 1 mg/kg body weight weekly). Drug treatment was continued for 6 weeks. The biomechanical results indicated methylprednisolone significantly deteriorated the mechanical properties of the grafted ulnae and the contralateral intact ulnae, although the effects were more pronounced in the grafted side. In Group B, there was minimum effect of ketorolac on the bone properties. In Group C, ketorolac significantly decreased the torsional stiffness and energy absorption of the grafted ulnae and also decreased the maximum torque in the intact and the grafted bones. It was concluded that the inhibitory effect of ketorolac on bone repair was dose dependent. In comparing the effects of ketorolac and methylprednisolone, the latter is more pronounced on torsional stiffness, but the effects on maximum torque and energy absorption were similar to ketorolac. The mechanism of the effects of ketorolac needs additional investigation.

Animals↗
PubMed1995

How sexually permissive are Singaporeans?

This paper presents data on two surveys done in 1989 and 1992 that indicated the attitudes of Singaporeans to sexuality. Both surveys revealed that Singaporeans have sexually conservative attitudes and those who have a lower education, are single, above the age of 40, are Malays/Muslims hold more conservative views.

Adolescent↗
PubMed1994

Calcium kinetics in lactating women with low and high calcium intakes.

Absorption of calcium and its mobilization from bone during lactation are important for delivery of calcium to breast-feeding infants; whether calcium intake offsets bone resorption is not known. We hypothesized that calcium absorption is increased in lactation and greater in women on low calcium diets, resulting in similar rates of bone resorption and accretion. Calcium absorption and kinetic indexes were calculated by using two stable isotopic tracers in 8 women; 6 were studied both during lactation and nonlactation. Women consumed low calcium diets, with half receiving supplemental calcium. Intestinal absorption was related to serum 1,25-dihydroxyvitamin D and did not increase during lactation. Despite decreased urinary calcium excretion during lactation, especially in women with low calcium intake, net balance tended to be lower during lactation. Mean residence time decreased and bone resorption exceeded accretion in almost all lactating women. Calcium need for milk production appears to be met by decreased urinary excretion and increased bone resorption, and not by increased intestinal absorption.

Adult↗
PubMed1994

Seasonal and geographical variations in the growth rate of infants in China receiving increasing dosages of vitamin D supplements.

In theory, sunshine exposure is sufficient to maintain normal vitamin D concentrations for the optimal growth of newborn infants. To determine whether season of birth, latitude (north v. south) and increasing dosages of vitamin D supplements would influence the growth rate for the first 6 months of life, 255 healthy fall-and spring-born infants from two northern and two southern cities in China were randomly assigned to receive either 100, 200, or 400 IU of vitamin D a day. The study showed that season of birth and dose of vitamin D did not affect the growth rate of infants born in the same latitude, but a significant difference was found in the gain in length over the 6-month period between infants from the north and infants from the south (P = 0.0001). Regional differences among the Chinese people, other than sunshine exposure, may have influenced the difference in length gain.

Anthropometry↗
PubMed1994

Low bone mineral content and high serum osteocalcin and 1,25-dihydroxyvitamin D in summer- versus winter-born newborn infants: an early fetal effect?

Seasonal differences in bone mineral indices have not been studied in newborn infants. In adults, indicators of bone metabolism may show seasonal variations. In postneonatal infants and possibly in adults, vitamin D metabolism shows seasonal variations. We hypothesized that in winter-born infants, the bone mineral content is low and serum osteocalcin is high, related to increased bone turnover and high serum 1,25-dihydroxyvitamin D [1,25(OH)2D]. We studied 246 healthy, term appropriate-for-gestation infants in winter (January through March; 140 children) and summer (July through September; 106 children). The bone mineral content (BMC) of the one-third distal radius was measured before 3 days of age by photon absorptiometry. Significant seasonal differences were found: summer-born infants had significantly lower BMC, higher serum osteocalcin and 1,25(OH)2D, and lower serum total calcium than winter-born infants. Seasonal differences in BMC remained significant after adjusting for race and sex. BMC was not correlated with serum biochemical measures. Thus, summer-born newborn infants have low BMC and high serum osteocalcin and 1,25(OH)2D than winter-born infants; these findings are the opposite of adult findings. We suggest that seasonal effects on fetal bone operate especially in early pregnancy (approximately 6 months before birth) resulting in a "phase effect" and opposite findings from later life.

Black People↗
PubMed1994

Long-term evaluation of immune status in leprosy patients undergoing multiple drug therapy.

A long-term survey of leprosy patients of all clinical types, starting at the time of diagnosis, was carried out to monitor clinical, bacteriological and immunological parameters at regular intervals during multiple drug therapy (MDT). The patients were assigned to two groups for treatment following WHO guidelines: paucibacillary (PB) and multibacillary (MB). Immunoglobulin levels, specific antibodies, skin-test responses to different soluble mycobacterial antigens (new tuberculins), and in vitro proliferative responses to mitogens and to antigens were measured during treatment, as were clinical changes, the bacterial index, and clinical improvement. No exact relations between disease activity and IgM antibody levels, both IgM immunoglobulin and specific IgM antibody to a species-specific antigen (ND-O-BSA), could be seen for MB patients. Changes in in vitro cell-mediated immunity and skin-test response seemed to be more directly related to the bacterial load and could reflect the improvement of bacteriological and clinical parameters during MDT.

Agglutination Tests↗
PubMed1993

Reduced serum osteocalcin and 1,25-dihydroxyvitamin D concentrations and low bone mineral content in small for gestational age infants: evidence of decreased bone formation rates.

In small for gestational age (SGA) infants, bone mineral content (BMC) is low but the reasons are unclear and the possible relationships between calcium-regulating hormones and BMC have not been studied. We hypothesized that BMC would be lower and concentrations of serum parathyroid hormone and 1,25-dihydroxyvitamin D would be higher at birth in SGA infants than in appropriate for gestational age (AGA) infants. Forty-two term SGA infants and 126 term AGA infants, matched 1:3 specifically by gestation (+/- 1 week) and birth month, were studied prospectively. The BMC of the distal one third of the radius was measured before 3 days of age by photon absorptiometry. The BMC was lower in SGA than in AGA infants. Both SGA and AGA infants had lower BMC in summer or spring than in winter; BMC differences between groups remained significant after adjustment for season (p = 0.0001). Cord serum osteocalcin and 1,25-dihydroxyvitamin D values were lower in SGA than in AGA infants. There were no differences between groups in cord serum levels of intact parathyroid hormone, 25-hydroxyvitamin D, calcium, phosphorus, and magnesium. Relationships were positive between BMC and birth weight and were inverse between BMC and intact parathyroid hormone values. We suggest that reduced uteroplacental blood flow in SGA infants may result in reduced fetal-placental production of 1,25-dihydroxyvitamin D, which results in low BMC and low serum osteocalcin values; fetal serum parathyroid hormone values may be relatively elevated because of reduced placental mineral supply.

Birth Weight↗
PubMed1993

The facilitatory effect of N-methyl-D-aspartate on sexual receptivity in female rats through GnRH release.

The purpose of this study was to examine whether N-methyl-D-aspartate affects the sexual receptivity of female rats. Monosodium L-glutamate was used as a neurotoxin to induce hypogonadal status. Matured normal and monosodium L-glutamate-treated rats were ovariectomized and implanted subcutaneously with estradiol capsules. One week later, lordosis responsiveness was observed before and 10 min after N-methyl-D-aspartate (40 mg/kg of BW, ip) administration. The results showed that N-methyl-D-aspartate caused a remarkable increase of lordosis quotient in control rats but not in monosodium L-glutamate-treated rats. Moreover, the possible action site of N-methyl-D-aspartate in the enhancement of receptivity was evaluated by the post-castrational LH rise, pituitary LH release in response to GnRH, and N-methyl-D-aspartate-evoked GnRH releasability. The results revealed that: (a) serum levels of LH in monosodium L-glutamate-treated rats were lower (p < 0.01) than those of control rats after ovariectomy; (b) there was no significant difference of pituitary LH release responsiveness to GnRH test between two groups; and (c) N-methyl-D-aspartate-evoked LH release in monosodium L-glutamate-treated rats was similar to that in the control rats. In conclusion, N-methyl-D-aspartate may facilitate the sexual receptivity through stimulating GnRH release. The failure of N-methyl-D-aspartate in enhancing receptivity in monosodium L-glutamate-treated rats is probably due to the cellular damage by monosodium L-glutamate on specific areas responsible for lordosis.

Animals↗
PubMed1993

[The mechanism of the pineal gland in inhibiting sexual receptivity of female rats treated with monosodium-L-glutamate: (III). Does it concern with the function of the pituitary gland?].

To elucidate whether pituitary function participates in the effect of the pineal gland on sexual receptivity, monosodium L-glutamate (MSG) was used as a neurotoxin to induce hypogonadal status. Long-Evans rats were divided into four groups: (1) normal control (C), (2) pinealectomized (Px), (3) MSG-treated (MSG) and (4) pinealectomized MSG-treated (Px-MSG). Pinealectomy was performed at six weeks of age. In the first part of the experiment, the sexual receptivity was estimated at the age of 2.5 months by lordosis quotient (LQ). The result indicates that the decline of receptivity by neonatal MSG treatment can be significantly improved by pinealectomy. In the second part of the experiment, the effect of pinealectomy on pituitary function was examined by two tests including (1) post-castrational LH rise and (2) pituitary response to LHRH. Ovariectomy was performed at the age of 2.5 months. Four weeks later three consecutive blood samples were collected at 10 minute intervals for LH radioimmunoassay. Then, three doses of LHRH (100 ng, 250 ng and 500 ng/100 g of body weight) were administered separately at two-week intervals, serum samples were taken before as well as 15 and 60 minutes after LHRH administration. The results showed that there was no significant difference in serum LH levels between Px and control rats after ovariectomy. The LHRH-evoked LH elevation in Px-MSG rats was just the same as that of the MSG rats, although the LH level in MSG rats was lower than in the control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[The effects of neonatal monosodium glutamate treatment on sex-odor attractivity and approach behavior in rats].

The neurotoxic effects of monosodium glutamate (MSG) on certain parts of the central nervous system (CNS) and endocrine functions are well documented. MSG-treated rats exhibit stunted growth, obesity and decrease in sexual behavior. The present study was designed to evaluate how neonatal administration of MSG affects sex-odor attractivity and approach behavior, and to investigate factors limiting copulation in MSG-treated rats. In this experiment, subcutaneous injections of MSG (400 mg MSG/ml normal saline/0.1 Kg B.W.) were given to Long-Evans pups on days 1 and 3 after birth, whereas the control groups received normal saline injections of equal volume (1 ml/0.1 kg B.W.). When the rats were 3 months old, sex-odor attractivity and approach behavior were tested. Two points were displayed by MSG-treated rats: (a) attenuated the attractivity of sex-odor. (b) decreased performance of sexual approach to partners. From our results and those of a previous study, we suggest that the deterioration of sex-odor attractivity and approach behavior to partners is attributed to a decline in sexual hormones. Furthermore, we concluded that this decrease in behaviors is to some extent responsible for reduced copulatory behavior.

Animals↗
PubMed1992

Prospective study of vitamin D supplementation and rickets in China.

To determine whether amounts of vitamin D lower than recommended doses are effective in preventing rickets, 256 term infants from two northern and two southern cities in China were studied in a randomized trial of vitamin D supplementation (100, 200, or 400 IU/day) during the first 6 months of life. Cord blood and 6-month blood samples were collected and radiographs were obtained at 3 to 5 days and at 6 months of age. Cord serum 25-hydroxyvitamin D concentrations were lower in the north than in the south (5 vs 14 ng/ml (12.5 vs 35.0 nmol/L); p less than 0.01). Wrist ossification centers were less likely to be present at birth in the northern children than in the southern children (p = 0.009) and were more likely to be present in infants born in the fall who had higher cord serum concentrations of 25-hydroxyvitamin D (p = 0.04). Serum 25-hydroxyvitamin D concentrations were lower in northern children 6 months of age than in southern children (p = 0.005) and were higher with an increasing supplemental dosage of vitamin D (p less than 0.001), particularly in infants in the north. None of the infants had rickets at 6 months of age. Because of the low serum 25-hydroxyvitamin D concentrations, especially among infants in the north, it may be prudent to supplement the diet with vitamin D at a dose of 400 IU/day.

China↗
PubMed1992

Low bone mineral content in summer-born compared with winter-born infants.

Possible seasonal differences in newborn bone mineral content (BMC) have not been studied. Adult studies show seasonal variations with lower BMC in winter versus summer. Assuming that BMC variations may relate in part to vitamin D status, we hypothesized that newborn BMC would be lower in winter than summer. BMC of one third distal radius was measured in 55 healthy term newborns using a single beam photon absorptiometer [coefficient of variation (CV) for phantom standard 2.1%]. Infants were enrolled during summer (July-September, 1988) and winter (January-March, 1989) for a longitudinal nutrition study. Contrary to our hypothesis, there was a 12% lower BMC in summer versus winter (mean +/- SD 75.94 +/- 17.42 vs. 86.55 +/- 17.54 mg/cm, respectively; p = 0.035). The difference remained significant after controlling for possible race and gender effects (p = 0.02). We conclude that BMC is lower in summer- compared with winter-born infants. Since any seasonal effects on fetal bone are presumably related to effects through the mother, we speculate that if maternal vitamin D status influences fetal bone mineralization, the effect (possible sunshine deprivation in winter) may operate especially in early pregnancy, thus resulting in lower BMC, evident at birth in summer.

Black People↗
PubMed1992

Ovarian and circulating levels of oxytocin and arginine vasopressin during the estrous cycle in the rat.

Ovarian extracts of Long-Evans rats separated using high performance liquid chromatography (HPLC) were measured by radioimmunoassays (RIAs) for the presence of oxytocin and arginine vasopressin (AVP). The results showed that the ovary contains both, and that they are indistinguishable from the respective standard synthetic peptides. During the estrous cycle, the ovarian content of oxytocin was 10-fold higher (p less than 0.01) in estrus than in the other phases, while AVP was 16- and 25-fold higher (p less than 0.01) in metestrus than in the other phases. In contrast, the plasma levels of oxytocin showed no significant difference among the various phases of the estrous cycle. However, the plasma level of AVP level was significantly higher (p less than 0.01) in diestrus than in other phases. The present study thus strongly supports the hypothesis that both oxytocin and AVP can be produced by the ovary itself in the rat. The possible roles of oxytocin and AVP in the reproductive cycle are discussed.

Animals↗
PubMed1992

A survey of sexual behaviour of Singaporeans.

In order to plan education programmes against sexually transmitted diseases (STDs) and HIV infection, a population-based survey on partner relations was conducted on 2,115 Singaporean men and women aged between 15 and 49 years. Of the 605 (60.1%) sexually experienced men and 647 (58.3%) sexually experienced women, 510 (84.3%) men and 644 (99.5%) women were married. Of the marrieds, 465 (76.9%) men and 638 (98.6%) women had their first sexual encounter with the person who was or later became their spouse. Of the sexually experienced men, 97 (16%) engaged in casual sex in the previous year, of which 76 (78.4%) were encounters with commercial sex workers. Of these encounters 55 (72.4%) were unprotected or partially protected by condoms. A history of casual sex in the previous four weeks was given by 18 men, of whom 14 (77.8%) were married. Nine (64.3%) of these married men had sex concurrently with both their wives and commercial workers. Persons at high risk were those who started sexual activity early, unmarried, sexually active men with no or low education, and persons who travelled. Of the sexually experienced respondents, 1,242 (99.2%) had heard about condoms, and 431 (34.4%) were currently using them as contraceptive devices. Attitudes towards condoms and willingness to use them to prevent STDs and HIV infection were favourable. Men were more permissive in their attitudes towards sex. The level of permissiveness in men and women was not corroborated by their reported behaviour, an indication of either under-reporting and/or a disparity between attitude and practice.

Adolescent↗