Mortality of breast cancer in Taiwan, 1971-2010: temporal changes and an age-period-cohort analysis.

The current paper describes the age, period and cohort effects on breast cancer mortality in Taiwan. Female breast cancer mortality data were collected from the Taiwan death registries for 1971-2010. The annual percentage changes, age- standardised mortality rates (ASMR) and age-period-cohort model were calculated. The mortality rates increased with advancing age groups when fixing the period. The percentage change in the breast cancer mortality rate increased from 54.79% at aged 20-44 years, to 149.78% in those aged 45-64 years (between 1971-75 and 2006-10). The mortality rates in the 45-64 age group increased steadily from 1971 to 1975 and 2006-10. The 1951 birth cohorts (actual birth cohort; 1947-55) showed peak mortalities in both the 50-54 and 45-49 age groups. We found that the 1951 birth cohorts had the greatest mortality risk from breast cancer. This might be attributed to the DDT that was used in large amounts to prevent deaths from malaria in Taiwan. However, future researches require DDT data to evaluate the association between breast cancer and DDT use.

Deep Learning for Synthetic CT from Bone MRI in the Head and Neck.

BACKGROUND AND PURPOSE: Bone MR imaging techniques enable visualization of cortical bone without the need for ionizing radiation. Automated conversion of bone MR imaging to synthetic CT is highly desirable for downstream image processing and eventual clinical adoption. Given the complex anatomy and pathology of the head and neck, deep learning models are ideally suited for learning such mapping. MATERIALS AND METHODS: This was a retrospective study of 39 pediatric and adult patients with bone MR imaging and CT examinations of the head and neck. For each patient, MR imaging and CT data sets were spatially coregistered using multiple-point affine transformation. Paired MR imaging and CT slices were generated for model training, using 4-fold cross-validation. We trained 3 different encoder-decoder models: Light_U-Net (2 million parameters) and VGG-16 U-Net (29 million parameters) without and with transfer learning. Loss functions included mean absolute error, mean squared error, and a weighted average. Performance metrics included Pearson R, mean absolute error, mean squared error, bone precision, and bone recall. We investigated model generalizability by training and validating across different conditions. RESULTS: The Light_U-Net architecture quantitatively outperformed VGG-16 models. Mean absolute error loss resulted in higher bone precision, while mean squared error yielded higher bone recall. Performance metrics decreased when using training data captured only in a different environment but increased when local training data were augmented with those from different hospitals, vendors, or MR imaging techniques. CONCLUSIONS: We have optimized a robust deep learning model for conversion of bone MR imaging to synthetic CT, which shows good performance and generalizability when trained on different hospitals, vendors, and MR imaging techniques. This approach shows promise for facilitating downstream image processing and adoption into clinical practice.

The remarkable influence of M2delta to thienyl pi conjugation in oligothiophenes incorporating MM quadruple bonds.

Oligothiophenes incorporating MM quadruple bonds have been prepared from the reactions between Mo(2)(TiPB)(4) (TiPB = 2,4,6-triisopropyl benzoate) and 3',4'-dihexyl-2,2'-:5',2''-terthiophene-5,5''-dicarboxylic acid. The oligomers of empirical formula Mo(2)(TiPB)(2)(O(2)C(Th)-C(4)(n-hexyl)(2)S-(Th)CO(2)) are soluble in THF and form thin films with spin-coating (Th = thiophene). The reactions between Mo(2)(TiPB)(4) and 2-thienylcarboxylic acid (Th-H), 2,2'-bithiophene-5-carboxylic acid (BTh-H), and (2,2':5',2''-terthiophene)-5-carboxylic acid (TTh-H) yield compounds of formula trans-Mo(2)(TiPB)(2)L(2), where L = Th, BTh, and TTh (the corresponding thienylcarboxylate), and these compounds are considered as models for the aforementioned oligomers. In all cases, the thienyl groups are substituted or coupled at the 2,5 positions. Based on the x-ray analysis, the molecular structure of trans-Mo(2)(TiPB)(2)(BTh)(2) reveals an extended Lpi-M(2)delta-Lpi conjugation. Calculations of the electronic structures on model compounds, in which the TiPB are substituted by formate ligands, reveal that the HOMO is mainly attributed to the M(2)delta orbital, which is stabilized by back-bonding to one of the thienylcarboxylate pi* combinations, and the LUMO is an in-phase combination of the thienylcarboxylate pi* orbitals. The compounds and the oligomers are intensely colored due to M(2)delta-thienyl carboxylate pi* charge transfer transitions that fall in the visible region of the spectrum. For the molybdenum complexes and their oligomers, the photophysical properties have been studied by steady-state absorption spectroscopy and emission spectroscopy, together with time-resolved emission and transient absorption for the determination of relaxation dynamics. Remarkably, THF solutions the molybdenum complexes show room-temperature dual emission, fluorescence and phosphorescence, originating mainly from (1)MLCT and (3)MM(deltadelta*) states, respectively. With increasing number of thienyl rings from 1 to 3, the observed lifetimes of the (1)MLCT state increase from 4 to 12 ps, while the phosphorescence lifetimes are approximately 80 micros. The oligomers show similar photophysical properties as the corresponding monomers in THF but have notably longer-lived triplet states, approximately 200 micros in thin films. These results, when compared with metallated oligothiophenes of the later transition elements, reveal that M(2)delta-thienyl pi conjugation leads to a very small energy gap between the (1)MLCT and (3)MLCT states of <0.6 eV.

Simvastatin increases osteoblasts and osteogenic proteins in ovariectomized rats.

BACKGROUND: Previous reports have indicated that statins could prevent bone loss in ovariectomized (OVX) rats and increase the expressions of osteogenic genes in cultured osteoblasts. In this study, we hypothesized that simvastatin might increase osteoblast number and protein expressions of osteogenic markers localized in bones in concomitance with the prevention of bone loss in OVX rats. MATERIALS AND METHODS: Fifty-four 3-month-old OVX and sham-operated (SHAM) female Sprague-Dawley rats were used. Simvastatin (10-20 mg kg(-1) day(-1)) was administrated orally for 6 weeks. Trabecular volume, osteoblast number and osteogenic proteins including BMP2, collagen type I and osteocalcin on bone sections obtained from lumbar vertebral body, distal femur and proximal tibia were measured. RESULTS: The results showed that SHAM rats had significantly less trabecular bone volume and osteoblast number than that of OVX rats 6 weeks after operation. Oral simvastatin treatment (10-20 mg kg(-1) day(-1)) increased bone volume and osteoblast number in the distal femurs, proximal tibiae and vertebrae of OVX rats. Furthermore, the osteoblastic cells with immuno-stained BMP2, collagen type I and osteocalcin in vertebral bones were significantly increased by simvastatin treatment (20 mg kg(-1) day(-1)) in OVX rats. CONCLUSIONS: This study demonstrates that simvastatin enhances the production of osteogenic proteins in bone and this effect may contribute to the prevention of bone loss in OVX rats.

Zero TE MRI for Craniofacial Bone Imaging.

Zero TE MR imaging is a novel technique that achieves a near-zero time interval between radiofrequency excitation and data acquisition, enabling visualization of short-T2 materials such as cortical bone. Zero TE offers a promising radiation-free alternative to CT with rapid, high-resolution, silent, and artifact-resistant imaging, as well as the potential for "pseudoCT" reconstructions. In this report, we will discuss our preliminary experience with zero TE, including technical principles and a clinical case series demonstrating emerging applications in neuroradiology.

Reducing off target viral delivery in ovarian cancer gene therapy using a protease-activated AAV2 vector platform.

Gene therapy is a promising strategy for treating metastatic epithelial ovarian cancer (EOC). However, efficient vector targeting to tumors is difficult and off-target effects can be severely detrimental. Most vector targeting approaches rely on surface receptors overexpressed on some subpopulation of cancer cells. Unfortunately, there is no universally expressed cell surface biomarker for tumor cells. As an alternative, we developed an adeno-associated virus (AAV) based "Provector" whose cellular transduction can be activated by extracellular proteases, such as matrix metalloproteinases (MMP) that are overexpressed in the tumor microenvironments of the most aggressive forms of EOC. In a non-tumor bearing mouse model, the Provector demonstrates efficient de-targeting of healthy tissues, especially the liver, where viral delivery is <1% of AAV2. In an orthotopic HeyA8 tumor model of EOC, the Provector maintains decreased off-target delivery in the liver and other tissues but with no loss in tumor delivery. Notably, approximately 10% of the injected Provector is still detected in the blood at 24 h while >99% of injected AAV2 has been cleared from the blood by 1 h. Furthermore, mouse serum raised against the Provector is 16-fold less able to neutralize Provector transduction compared to AAV2 serum neutralizing AAV2 transduction (1:200 vs 1:3200 serum dilution, respectively). Thus, the Provector appears to generate less neutralizing antibodies than AAV2. Importantly, serum against AAV2 does not neutralize the Provector as well as AAV2, suggesting that pre-existing antibodies against AAV2 would not negate the clinical application of Provectors. Taken together, we present an EOC gene delivery vector platform based on AAV with decreased off-target delivery without loss of on-target specificity, and greater immunological stealth over the traditional AAV2 gene delivery vector.

Spectrum of Third Window Abnormalities: Semicircular Canal Dehiscence and Beyond.

Third window abnormalities are defects in the integrity of the bony structure of the inner ear, classically producing sound-/pressure-induced vertigo (Tullio and Hennebert signs) and/or a low-frequency air-bone gap by audiometry. Specific anatomic defects include semicircular canal dehiscence, perilabyrinthine fistula, enlarged vestibular aqueduct, dehiscence of the scala vestibuli side of the cochlea, X-linked stapes gusher, and bone dyscrasias. We discuss these various entities and provide key examples from our institutional teaching file with a discussion of symptomatology, temporal bone CT, audiometry, and vestibular-evoked myogenic potentials.

Role of Tetra Amino Acid Motif Properties on the Function of Protease-Activatable Viral Vectors.

Protease-activatable viruses (PAV) based on adeno-associated virus have previously been generated for gene delivery to pathological sites characterized by elevated extracellular proteases. "Peptide locks", composed of a tetra-aspartic acid motif flanked by protease cleavage sequences, were inserted into the virus capsid to inhibit virus-host cell receptor binding and transduction. In the presence of proteases, the peptide locks are cleaved off the capsid, restoring the virus' ability to bind cells and deliver cargo. Although promising, questions remained regarding how the peptide locks prevented cell binding. In particular, it was unclear if the tetra-amino acid (4AA) motif blocks receptor binding via electrostatic repulsion or steric obstruction. To explore this question, we generated a panel of PAVs with lock designs incorporating altered 4AA motifs, each wielding various chemical properties (negative, positive, uncharged polar, and hydrophobic) and characterized the resultant PAV candidates. Notably, all mutants display reduced receptor binding and decreased transduction effciency in the absence of proteases, suggesting simple electrostatics between heparin and the D4 motif do not play an exclusive role in obstructing virus-receptor binding. Even small hydrophobic (A4) and uncharged polar (SGGS) motifs confer a reduction in heparin binding compared to the wild type. Furthermore, both uncharged polar N4 and Q4 mutants (comparable in size to the D4 and E4 motifs respectively, but lacking the negative charge) demonstrate partial ablation of heparin binding. Collectively, these results support a possible dual mechanism of PAV lock operation, where steric hindrance and electrostatics make nonredundant contributions to the disruption of virus-receptor interactions. Finally, because of high virus titer production and superior capsid stability, only the negatively charged 4AA motifs remain viable design choices for PAV construction. Future studies probing the structure-function relationship of PAVs will further expand its promise as a gene delivery vector able to target diseased tissues exhibiting elevated extracellular proteases.

Regional brain metabolic changes in patients with major depression treated with either paroxetine or interpersonal therapy: preliminary findings.

BACKGROUND: In functional brain imaging studies of major depressive disorder (MDD), regional abnormalities have been most commonly found in prefrontal cortex, anterior cingulate gyrus, and temporal lobe. We examined baseline regional metabolic abnormalities and metabolic changes from pretreatment to posttreatment in subjects with MDD. We also performed a preliminary comparison of regional changes with 2 distinct forms of treatment (paroxetine and interpersonal psychotherapy). METHODS: Twenty-four subjects with unipolar MDD and 16 normal control subjects underwent resting F 18 ((18)F) fluorodeoxyglucose positron emission tomography scanning before and after 12 weeks. Between scans, subjects with MDD were treated with either paroxetine or interpersonal psychotherapy (based on patient preference), while controls underwent no treatment. RESULTS: At baseline, subjects with MDD had higher normalized metabolism than controls in the prefrontal cortex (and caudate and thalamus), and lower metabolism in the temporal lobe. With treatment, subjects with MDD had metabolic changes in the direction of normalization in these regions. After treatment, paroxetine-treated subjects had a greater mean decrease in Hamilton Depression Rating Scale score (61.4%) than did subjects treated with interpersonal psychotherapy (38.0%), but both subgroups showed decreases in normalized prefrontal cortex (paroxetine-treated bilaterally and interpersonal psychotherapy-treated on the right) and left anterior cingulate gyrus metabolism, and increases in normalized left temporal lobe metabolism. CONCLUSIONS: Subjects with MDD had regional brain metabolic abnormalities at baseline that tended to normalize with treatment. Regional metabolic changes appeared similar with the 2 forms of treatment. These results should be interpreted with caution because of study limitations (small sample size, lack of random assignment to treatment groups, and differential treatment response between treatment subgroups).

Brain metabolic changes associated with symptom factor improvement in major depressive disorder.

BACKGROUND: Symptoms of major depressive disorder (MDD) have been linked to regional brain function through imaging studies of symptom provocation in normal control subjects and baseline studies of subjects with MDD. We examined associations between change in depressive symptom factors and change in regional brain metabolism from before to after treatment of MDD. METHODS: Thirty-nine outpatients with MDD underwent 18F-fluorodeoxyglucose positron emission tomography scanning before and after treatment with either paroxetine or interpersonal psychotherapy. Associations were determined between changes in regional brain metabolism and changes in four Hamilton Depression Rating Scale factors (anxiety/somatization [ANX], psychomotor retardation [PR], cognitive disturbance [COGN], and sleep disturbance) and two corresponding Profile of Mood States subscales (tension [TENS] and fatigue [FATIG]). RESULTS: Improvement in ANX, PR, TENS, and FATIG factors was associated with decreasing ventral frontal lobe metabolism. Improvement in ANX and TENS was also associated with decreasing ventral anterior cingulate gyrus (AC) and anterior insula activity, whereas improvement in PR was associated with increasing dorsal AC activity. COGN improvement was associated with increasing dorsolateral prefrontal cortex metabolism. CONCLUSIONS: Brain regions that show significant relationships with symptom provocation in normal control subjects have similar relationships with MDD symptoms as they improve with treatment.

Cerebral metabolism in major depression and obsessive-compulsive disorder occurring separately and concurrently.

BACKGROUND: The frequent comorbidity of major depressive disorder (MDD) and obsessive-compulsive disorder (OCD) suggests a fundamental relationship between them. We sought to determine whether MDD and OCD have unique cerebral metabolic patterns that remain the same when they coexist as when they occur independently. METHODS: [18F]-fluorodeoxyglucose positron emission tomography (PET) brain scans were obtained on 27 subjects with OCD alone, 27 with MDD alone, 17 with concurrent OCD+MDD, and 17 normal control subjects, all in the untreated state. Regional cerebral glucose metabolism was compared between groups. RESULTS: Left hippocampal metabolism was significantly lower in subjects with MDD alone and in subjects with concurrent OCD+MDD than in control subjects or subjects with OCD alone. Hippocampal metabolism was negatively correlated with depression severity across all subjects. Thalamic metabolism was significantly elevated in OCD alone and in MDD alone. Subjects with concurrent OCD+MDD had significantly lower metabolism in thalamus, caudate, and hippocampus than subjects with OCD alone. CONCLUSIONS: Left hippocampal dysfunction was associated with major depressive episodes, regardless of primary diagnosis. Other cerebral metabolic abnormalities found in OCD and MDD occurring separately were not seen when the disorders coexisted. Depressive episodes occurring in OCD patients may be mediated by different basal ganglia-thalamic abnormalities than in primary MDD patients.

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.

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.

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.

Trial on timing of introduction to solids and food type on infant growth.

OBJECTIVE: The optimal time and choice of solid foods to introduce to an infant's diet is unknown. The aim of this randomized trial was to determine whether early versus late introduction of solid foods and commercially prepared versus parent's choice of solid foods affects growth or body composition in the first year. METHODS: White infants (n = 165) were recruited before 3 months of age and were randomized to receive: 1) commercially prepared solid foods (commercial) from 3 to 12 months, 2) commercially prepared solid foods from 6 to 12 months, 3) parent's choice of solid foods (choice) from 3 to 12 months, or 4) parent's choice of solid foods from 6 to 12 months. Anthropometrics and body composition, using dual energy x-ray absorptiometry, were determined at 3, 6, and 12 months. Three-day diet diaries were completed at 3, 6, 9, and 12 months. RESULTS: There were no differences in growth or body composition between infants in early versus late introduction groups or commercial versus choice groups at any age. The total energy intake was not different among infants in the early compared with the late group at any age. Infants in the commercial group consumed less protein calories at 9 months (80 +/- 3 kcal/d vs 88 +/- 3 kcal/d) and 12 months 101 +/- 5 kcal/d vs 148 +/- 5 kcal/d), less fat calories at 12 months (263 +/- 10 kcal/d vs 343 +/- 10 kcal/d), and less total calories at 12 months (884 +/- 24 kcal/d vs 1022 +/- 25 kcal/d) compared with the choice group. CONCLUSION: The early introduction of solid foods to an infant's diet does not alter growth or body composition during the first year of life and results in a displacement of energy intake from formula. Infants consuming commercially prepared foods have a decreased caloric intake from protein and fat; however, despite this difference, there is no effect on growth or body composition.

Effects of nonsteroidal anti-inflammatory drugs and prostaglandins on osteoblastic functions.

It has been reported that nonsteroidal anti-inflammatory drugs (NSAIDs) suppress bone repair and bone remodeling but only mildly inhibit bone mineralization at the earlier stage of the repair process. We proposed that the proliferation and/or the earlier stage of differentiation of osteoblasts may be affected by NSAIDs. This study was designed to investigate whether NSAIDs affect the proliferation and/or differentiation of osteoblasts and whether these effects are prostaglandin (PG) mediated. The effects of PGE1 and PGE2, indomethacin, and ketorolac on thymidine incorporation, cell count, intracellular alkaline phosphatase (ALP) activity, and Type I collagen content in osteoblast-enriched cultures derived from fetal calvaria were evaluated. The results showed that both PGs and NSAIDs inhibited DNA synthesis and cell mitosis in a time- and concentration-dependent manner. However, intracellular ALP activity and Type I collagen content were stimulated at an earlier stage of differentiation in osteoblasts. These results suggested that (i) the inhibitory effect of ketorolac on osteoblastic proliferation contributes to its suppressive effects on bone repair and remodeling in vivo; (ii) PGEs and NSAIDs may be involved in matrix maturation and biologic bone mineralization in the earlier stage of osteoblast differentiation; and (iii) the effects of ketorolac and indomethacin on cell proliferation and differentiation may not be through the inhibition of the synthesis of PGE1 or PGE2.

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.

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.

PIP: Between June and December 1990, 806 prostitutes registered with the STD program in Singapore for regular screening for sexually transmitted diseases (STDs) 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 iv drug use (0.9%) were rare. The overall STD incidence rate was 47.7/100. None was human immunodeficiency virus (HIV) positive. The crude and age-adjusted risk of STDs 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 the majority of clients (85.5%) who did not use condoms spontaneously, they were successful with only about 1/2 of them (54.4%). Health education should be aimed at those clients on the protective effects of condom use and at the prostitutes on skills in negotiating condom use.

Evidence for multiple satellite cell populations and a non-myogenic cell type that is regulated differently in regenerating and growing skeletal muscle.

We have performed studies to determine if different populations of satellite cells provide nuclei to growing and regenerating skeletal muscle fibers. Satellite cells were isolated from regenerating or growing anterior tibialis muscles, and their phenotypic properties were compared in vitro. Isolates from regenerating muscle contained 31% satellite cells, and those from control muscle contained 66% satellite cells, as determined by their expression of desmin. Among the desmin-positive satellite cells present from each preparation, two distinct populations of satellite cells were evident. Approximately 28% of satellite cell colonies were composed of only large cells, contained less than 50 cells/colony, and were designated as type 1 colonies. The remainder of satellite cell colonies isolated from either regenerating or control muscles were primarily composed of small cells, contained from 60 to 150 cells/colony, and were designated as type 2 colonies. Despite dramatic differences in the ratio of myogenic to non-myogenic cell types, satellite cells from regenerating and control muscles formed myotubes and expressed myosin heavy chain at similar levels. Treatment of regenerating cultures with dexamethasone resulted in a 16% increase in the number of desmin-positive colonies and dramatically decreased the proliferation of non-myogenic cells. These results suggest that at least two distinct populations of satellite cells can be isolated from regenerating and control skeletal muscles, and that non-myogenic cells are differentially regulated in regenerating versus non-regenerating environments.

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.