Molecular epidemiology of tuberculosis in Cambodian children.

SUMMARY We analysed Mycobacterium tuberculosis strains from children, hospitalized from January 2004 to July 2008 in the largest paediatric hospital complex in Cambodia. Specimens were tested for drug susceptibility and genotypes. From the 260 children, 161 strains were available. The East African-Indian genotype family was the most common (59.0%), increasing in frequency with distance from the Phnom Penh area, while the frequency of the Beijing genotype family strains decreased. The drug resistance pattern showed a similar geographical gradient: lowest in the northwest (4.6%), intermediate in the central (17.1%), and highest in the southeastern (30.8%) parts of the country. Three children (1.9%) had multidrug-resistant tuberculosis. The Beijing genotype and streptomycin resistance were significantly associated (P < 0.001). As tuberculosis in children reflects recent transmission patterns in the community, multidrug resistance levels inform about the current quality of the tuberculosis programme.

Two clustered cases of confirmed influenza A(H5N1) virus infection, Cambodia, 2011.

In February 2011, a mother and her child from Banteay Meanchey Province, Cambodia, were diagnosed, postmortem, with avian influenza A(H5N1) virus infection. A field investigation was conducted by teams from the Cambodian Ministry of Health, the World Health Organization and the Institut Pasteur in Cambodia. Nasopharyngeal, throat and serum specimens collected from 11 household or three neighbour contacts including two suspect cases tested negative by reverse transcriptase-polymerase chain reaction (RT-PCR) for A(H5N1). Follow-up sera from the 11 household contacts also tested negative for A(H5N1) antibodies. Twenty-six HCW who were exposed to the cases without taking adequate personal protective measures self-monitored and none developed symptoms within the two following weeks. An unknown number of passengers travelling with the cases on a minibus while they were symptomatic could not be traced but no clusters of severe respiratory illnesses were detected through the Cambodian surveillance systems in the two weeks after that. The likely cause of the fatal infection in the mother and the child was common-source exposure in Preah Sdach District, Prey Veng Province. Human-to-human transmission of A(H5N1) virus was unlikely but genetic susceptibility is suspected. Clusters of A(H5N1) virus infection should be systematically investigated to rule out any human-to-human transmission.

Laboratory diagnosis of tuberculosis in a large pediatric hospital in Cambodia.

SETTING: Tuberculosis laboratory in the Jayavarman VII Children's Hospital in Siem Reap, part of the Kantha Bopha Hospitals, the largest pediatric hospital complex in Cambodia. OBJECTIVE: To determine the efficiency of on-site microscopy and rRNA amplification in children with a clinical diagnosis of tuberculosis (TB) and specimen sampling for culture. RESULTS: From 1 July 2005 to 31 March 2006, 52,400 children were admitted to the hospital. Among these, 405 children had tuberculosis, including 91 (22.5%) laboratory-confirmed cases, or respectively 7.7 and 1.7 per 1000 admissions. Among cases confirmed by microscopy or rRNA assay, rRNA identified 91.2%. Among all culture-confirmed cases, rRNA identified 90.5%. Culture alone contributed 7.1% to all laboratory confirmed cases. The yield of culture from preserved specimens was not affected by shipment delay. For 97.4% of the children, the maximum turnaround time for the on-site laboratory result was 48 h. CONCLUSION: Implementation of a mycobacteriology service in a referral hospital is feasible, as the molecular technique is highly efficient. Storage of specimen aliquots allows subsequent culture without loss of viability due to shipment delay.

Short-term vs long-term dexamethasone treatment: effects on rat diaphragm structure and function.

The effects of dexamethasone treatment duration (2.5 vs 10 weeks) on diaphragm myosin heavy chain isoforms, fiber types, and contractile characteristics were studied in male rats. Compared with ad libitum-fed and pair-fed controls, dexamethasone significantly decreased body weight, costal diaphragm weight, and the relative expression of myosin heavy chain isoform MHC-2B. Compared with pair-fed controls, the effect on MHC-2B expression was greater after 10 weeks than after 2.5 weeks. Type I and type II costal diaphragm fiber atrophy occurred, and type II fiber atrophy was greater after 10 weeks. Costal diaphragm-specific forces were not affected significantly by dexamethasone, regardless of the treatment duration or control group comparison. Fatigue resistance indexes were increased significantly after long term treatment compared with pair-fed controls and after both short-term and long-term treatment compared with ad libitum-fed controls. In conclusion, the effects of dexamethasone on MHC isoform phenotype expression, fiber type costal diaphragm atrophy, and fatigue resistance were dependent on treatment duration, with greater effects after long-term (10 weeks) treatment.

Spread of HIV-1 to children in Cambodia.

PIP: Beginning November 1, 1995, children under 5 years of age, who were admitted to Kantha Bopha Hospitals and who were suspected tuberculosis cases, were screened for human immunodeficiency virus 1 (HIV-1) using enzyme-linked immunosorbent assay (ELISA). By January 31, 1997, 9026 children, 83% of the under 5-year-olds admitted, had been tested; 290 (3.2%) were positive. Serum samples from 205 children of the 236 seropositive children under the age of 18 months were tested for p24 antigen; 51 (25%) were positive. Mothers of 173 of the seropositive children were tested for antibodies to HIV; 170 were positive, which suggests that the main mode of acquisition of HIV-1 in the children was vertical transmission. If HIV-1 infection occurred only in the 54 seropositive children older than 18 months and in the 51 children younger than 18 months with detectable p24 antigen, the calculated prevalence of HIV-1 in children under 5 years old who were suspected of having tuberculosis when admitted to Kantha Bopha Children's Hospitals would be 1.2%. If the 17% not included in the test were all negative, the prevalence would be 1%. This is an underestimate because some of the children not tested could be positive and because some of the children tested had indeterminate HIV status. HIV testing was extended to all children admitted to the hospital; 715 were younger than 5 years of age, 596 of whom were suspected of having tuberculosis, and 119 of whom were not. The seroprevalences for the 2 subgroups were 3.2% and 0.8%, respectively. None of the 369 older children was seropositive. In 1996, the World Health Organization estimated a seroprevalence of 1.97% in adults 15-49 years old in Cambodia, the highest among Asian countries. The blood bank at Kantha Bopha found 211 (6.6%) HIV-1 seropositives among 3197 donors in 1995 and 211 (7.5%) among 2834 donors in 1996. Similar figures were seen at the National Transfusion Centre in Phnom Penh. A 1996 survey in Cambodia found an HIV-1 seroprevalence of 40.9% in prostitutes and 1.7% in pregnant women. The vertical transmission of HIV-1 to children may increase because the virus appears to have been introduced recently to Cambodia; this is indicated by lack of seropositivity in children older than 5 years of age.^ieng

Gender-specific effects of dexamethasone treatment on rat diaphragm structure and function.

The effects of long-term dexamethasone treatment on diaphragm muscle were studied in female and male rats. Compared with pair-fed control animals, dexamethasone treatment did not significantly affect estrous cycling or peak serum estradiol levels; however, testosterone levels were significantly increased in females and decreased in males. Dexamethasone significantly reduced body and costal diaphragm weights, but to a lesser extent in females than in males. Reductions in diaphragm weight were proportional to reductions in body weight. In females and males, dexamethasone treatment significantly decreased diaphragm fiber (types I and II) cross-sectional area and the relative expression of myosin heavy chain isoform 2B. With the exception of type I fiber atrophy, these changes occurred to a lesser extent in females. Dexamethasone did not significantly affect specific forces. Dexamethasone significantly increased twitch one-half relaxation time and fatigue resistance indexes in males but not in females. In conclusion, the effects of long-term dexamethasone treatment were gender specific, with significantly fewer effects in females, and changes in serum testosterone levels were associated with these findings.

Effect of long-term undernutrition on male and female rat diaphragm contractility, fatigue, and fiber types.

The effects of long-term undernutrition (10 wk) on diaphragm contractility, fatigue, and fiber type proportions were studied in male and female rats. Contractility and fatigue resistance indexes were measured in an in vitro diaphragm costal strip preparation by using direct stimulation at 37 degrees C. Undernutrition allowed for continued growth in males and females but with substantial reductions in weight gain. Relative to control rats of the same sex, final weights were significantly lower in undernourished males (74 +/- 3%) than females (90 +/- 5%), but weight gain was not significantly different between undernourished males (58 +/- 5%) and females (60 +/- 3%). Only in males did undernutrition significantly reduce costal diaphragm weight (to 77 +/- 5% of control). Diaphragm forces, normalized for cross-sectional area, were not significantly different from male or female control values. Fatigue resistance indexes (fatigue/baseline force) were increased at all stimulation frequencies in undernourished males but not in undernourished females. Costal diaphragm atrophy, involving types I and II fibers, occurred in undernourished males but not in undernourished females. In conclusion, despite long-term undernutrition reducing weight gain to similar levels in males and females (relative to control), there was excellent preservation of diaphragm weight, function, and structure in females but, although diaphragm atrophy occurred, there was preserved contractility and increased fatigue resistance in males.

Effects of short-term and long-term androgen treatment on the diaphragm in male and female rats.

The effects of short-term (2.5 wk) and long-term (10 wk) testosterone propionate (2.5 mg/day; 5 days/wk) treatment on diaphragm contractility, fatigue resistance, and fiber type proportions were studied in male and female rats. Contractility and fatigue resistance indexes were measured in an in vitro diaphragm costal strip preparation by direct stimulation at 37 degrees C. The fatigue paradigm consisted of 30 trains/min at 5 Hz (50% duty cycle) for 10 min. Fatigue resistance indexes were calculated as postfatigue divided by baseline forces. In females but not males, testosterone treatment produced significant increases in body weight, costal diaphragm weight, and contractility and significant decreases in fatigue resistance indexes. The interaction between testosterone treatment and the duration of treatment was significant, with the increase in contractility (females) being significant after short-term but not long-term treatment. No significant difference in fiber type proportions or areas was observed, regardless of treatment duration or the preexperimental, basal circulating level of androgen.

Effects of long-term continuous respiratory resistive loading on rat diaphragm function and structure.

The effects of long-term (24- to 28-wk) continuous respiratory resistive loading on diaphragm mass, contractility, fatigue, and fiber types were studied in male rats. Increased respiratory resistance was produced by extratracheal banding, and results were compared with sham-operated pair-fed controls. At the time the animals were killed, banded tracheal segment internal diameter was reduced by 57% of control values. Diaphragm surface area and muscle mass (normalized for body mass) increased by 19% of control values. Isometric diaphragm contractility and fatigue resistance indexes were measured using an in vitro diaphragm costal strip preparation at 37 degrees C. Twitch and tetanic stimulations were evoked using direct stimulation. Compared with controls, baseline tensions (normalized for diaphragm cross-sectional area) were significantly decreased at low frequencies. Fatigue resistance (endurance) indexes were significantly increased at all frequencies. These findings were consistent with observed increases in number and cross-sectional area of type I (low-tension high-endurance) fibers. We conclude that the diaphragm adapts to chronic long-term resistive loads by sacrificing peak tensions for an increase in endurance capacity.

Temperature dependence of rat diaphragm muscle contractility and fatigue.

The diaphragm is a skeletal muscle of mixed fiber type that is unique in its requirement to maintain contractile function and fatigue resistance across a wide range of temperatures to sustain alveolar ventilation under conditions of hypo- or hyperthermia. The direct effect of temperature (15-41 degrees C) on rat diaphragm isometric contractility and fatigue was determined in vitro. As temperature decreased from 37 to 15 degrees C, contraction and relaxation times increased, and there was a left shift of the diaphragm's force-frequency curve, with decreased contractility at 41 and 15 degrees C. Fatigue was induced by 10 min of stimulation with 30 trains/min of 5 Hz at a train duration of 900 ms. Compared with 37 degrees C, fatigue resistance was enhanced at 25 degrees C, but no difference in fatigue indexes was evident at extreme hypothermia (15 degrees C) or hyperthermia (41 degrees C). Only when the fatigue program was adjusted to account for hypothermia-induced increases in tension-time indexes was fatigue resistance evident at 15 degrees C. These findings indicate that despite the diaphragm's unique location as a core structure, necessitating exposure to in vivo temperatures higher than found in limb muscle, the temperature dependence of rat diaphragm muscle contractility and fatigue is similar to that reported for limb muscle of mixed fiber type.

Mapping of the genes coding for the two major vaccinia virus core polypeptides.

We have mapped the genes coding for two major structural polypeptides of the vaccinia virus core by hybrid selection and transcriptional mapping. First, RNA was selected by hybridization to restriction fragments of the vaccinia virus genome, translated in vitro and the products were immunoprecipitated with antibodies against the two polypeptides. This approach allowed us to map the genes to the left hand end of the largest Hind III restriction fragment of 50 kilobase pairs. Second, transcriptional mapping of this region of the genome revealed the presence of the two expected RNAs. Both RNAs are transcribed from the leftward reading strand and the 5'-ends of the genes are separated by about 7.5 kilobase pairs of DNA. Thus, two genes encoding structural polypeptides with a similar location in the vaccinia virus particle are clustered at approximately 105 kilobase pairs from the left hand end of the 180 kilobase pair vaccinia virus genome.

Hearing impairment following therapy of Haemophilus influenzae meningitis.

From 97 children with bacteriologically confirmed Haemophilus influenzae meningitis, 39 were treated with chloramphenicol (before 1970) and 58 with ampicillin (since 1970). In 1977 all patients were followed up with history, clinical examination, and audiometry. Sensorineural hearing defect was found in 5 chloramphenicol patients and in 10 ampicillin patients. Of the 82 patients for whom treatment was begun within 48 h of onset of symptoms, only two showed hearing deficit, while 13 of the 15 patients in whom treatment was begun later suffered from hearing impairment. It appears that it is not the antibiotic, but the delay between onset of symptoms and start of therapy, that is decisive for the occurrence of inner ear impairment.