The tuberculosis pandemic today: routes of transmission and new target groups

Tuberculosis, a disease that has been with us since the dawn of time, shows little sign of disappearing. Declines in death rates observed for several centuries prior to 1960 have been reversed in recent decades. This is in spite of the fact that efficient means of controlling the disease have been available during this period. This article reviews experience in 3 communities: among the Inuit, who live in the region of the North Pole; in the Beijing Municipality in the People's Republic of China; and in a socially isolated community in South Africa. In the first 2 communities, dramatic declines in the burden of disease have been observed: in the Inuit community, this occurred after substantial intervention; in the Beijing Municipality it was done with limited resources. The third community in South Africa illustrates an alarming trend, with tuberculosis being seen in a variety of locations but in the absence of external agents such as HIV infection. Clearly we need to refocus our efforts to control this disease, making use of the new tools that are rapidly becoming available. This must be done without delay, before influences such as HIV infection put the possibility of control completely out of reach.

Dermal exposure to cinnamaldehyde alters lymphocyte subpopulations, number of interferon-gamma-producing cells, and expression of B7 costimulatory molecules and cytokine messenger RNAs in auricular lymph nodes of B6C3F1 mice

BACKGROUND

Although the Murine Local Lymph Node Assay (LLNA) is efficient in identifying chemicals with sensitizing potential, there is increasing need for alternative end points. Cinnamaldehyde (CIN) was chosen for evaluation based on its moderate potency and extensive use in fragrance materials.

OBJECTIVES

The purpose of the present studies is to incorporate some alternative end points, such as phenotypic analysis and cytokine production, into a modified LLNA/irritancy assay (IA) to evaluate the sensitization of female B6C3F1 mice to CIN.

METHODS

Several nontraditional end points, including the analysis of lymphocyte subpopulations, B7 costimulatory molecule and cytokine messenger RNA (mRNA) expression, and intracellular interferon-gamma (IFN-gamma) levels, were incorporated into a modified murine local lymph node (LLNA)/irritancy assay (IA) to evaluate the sensitization of female B6C3F1 mice to cinnamaldehyde (CIN).

RESULTS

The alternate end points used in these studies support the classification of CIN as a moderately potent sensitizer. Dermal treatment with CIN resulted in an increase in the percentage of B cells in the auricular lymph nodes (ALNs) and expression of the costimulatory molecule, B7-2, on B cells. Lymph node cells also showed increased transforming growth factor-beta1, migration-inhibition factor, and mild increases in IFN-gamma and interleukin-2 cytokine mRNA expression. Although the increase in IFN-gamma mRNA expression did not translate into increased intracellular IFN-gamma levels, the absolute number of T cells producing IFN-gamma in the ALNs increased. Conversely, the MEST did not classify CIN as a contact allergen.

CONCLUSION

The nontraditional end points used in the LLNA/IA were not as sensitive as the traditional radioisotope method used to assess cell proliferation. However, they may help identify compounds inappropriately classified as sensitizers or nonsensitizers by the LLNA and MEST.

[Study on diagnosis and treatment of infections multiple organ dysfunction syndrome by integrated traditional Chinese and Western medicine]

OBJECTIVE

To explore the diagnostic and therapeutic approach of integrated traditional Chinese and western medicine (TCM-WM) on infectious multiple organ dysfunction syndrome/multiple system and organ failure (MODS/MSOF) for elevating the successful rate of rescuing the patients.

METHODS

Diagnosis with western medicine and Syndrome Differentiation of TCM in 225 in-patients of acute infectious disease complicated with MODS/MSOF were conducted, and TCM treatment, based on western medical comprehensive treatment, was given to observe the effect and explore the mechanism of the TCM-WM therapy.

RESULTS

Up to the end of 1998, 161 cases of the 225 cases were successfully cured and 64 died, the mortality being 28.4%. Among them, 58 out of 140 cases of MSOF died, the mortality was accounted for 41.4%. In 106 cases conformed to the diagnostic criteria of MSOF proposed by Professor Knaus WA, USA, 52 cases were cured successfully and 54 died, the mortality being 50.9%.

CONCLUSION

TCM-WM treatment could elevate the therapeutic effect in treating MODS, the mechanism might be through improving the hemodynamic and hemorrheologic condition of patients to relieve nail-fold microcirculation disorder; influencing the levels of cytokine and inflammatory mediator, so as to alleviate the systemic inflammatory reaction, it might also abate the inhibited condition of gastro-intestinal motility, alleviate the intestinal flora imbalance, prevent intestinal bacteria and endotoxin malposition, and protect cells from peroxidation.

Cost effectiveness of DOTS and non-DOTS strategies for smear-positive pulmonary tuberculosis in Beijing

The cost-effectiveness of DOTS (Directly Observed Treatment, short course) and non-DOTS strategies for smear-positive pulmonary tuberculosis in Beijing was evaluated. Cost calculation was based on the expenses of drugs, chest X-ray films, sputum smears and cultures for the patients. Effectiveness of the intervention was assessed in two aspects: direct benefits to the patients treated and indirect benefits to the others through reduced transmission of tuberculosis; disability adjusted life of year (DALY) was used as an index. The results showed that one DALY could be saved with 45.7 Yuan by DOTS and 471.4 Yuan by non-DOTS. DOTS is a good control strategy for smear-positive tuberculosis.

Cloning, expression and characterization of a cDNA (6A8) encoding a novel human alpha-mannosidase

A 3300-bp cDNA (6A8) has been isolated from a human tonsil cell lambdagt11 cDNA library (GenBank accession number: AF044414). The 6A8 gene is localized on human chromosome 13q31-32. Its cDNA has an open reading frame from position 57 bp to 3243 bp, encoding a 1062 amino-acid polypeptide. The sequence of the polypeptide has 89% identity to rat liver ER alpha-mannosidase. Homogenates of COS-7 cells transfected with 6A8 cDNA showed an enhanced enzymatic activity with p-nitro-phenyl-alpha-D-mannopyranoside, which was not inhibited by swainsonine. These data suggest that 6A8 alpha-mannosidase belongs to the class II alpha-mannosidase. Western blot analysis showed a band for 6A8 cDNA encoded protein of approximately 120 kDa. Northern blot analysis revealed two 6A8 mRNA transcripts with different tissue distribution. Enhanced concanavalin A (ConA) binding to CNE-2L2 cells transfected with a reverse 6A8 DNA was observed, indicating that the 6A8 protein is an important cellular alpha-mannosidase.

The impact of directly-observed treatment on the epidemiology of tuberculosis in Beijing

SETTING

Fully supervised chemotherapy, or directly observed treatment (DOT), for newly detected smear-positive cases in Beijing, has been successfully implemented for two decades.

OBJECTIVE

To evaluate the progress made in tuberculosis control, and in particular to evaluate the impact of DOT on tuberculosis epidemiology in Beijing.

DESIGN

Epidemiological parameters on tuberculosis, consisting of mortality, prevalence, notification rate, tuberculous meningitis in children and initial drug resistance rate, were collected and analysed. Their trends were evaluated and compared with DOT implemented for new smear-positive cases in Beijing from 1978 to 1996.

RESULTS

The coverage of DOT for new smear-positive pulmonary tuberculosis cases has increased from 10% in 1978 to more than 90% since 1990. Since DOT was introduced in 1978, mortality from tuberculosis has declined by an average of more than 7% per year. The reduction rate of 17.2%, and the rates of chronic cases and tuberculous meningitis in children decreased dramatically. The rate of newly registered smear-positive cases decreased from 18.9/100000 in 1986 to 7.3/100000 in 1996, giving an average annual reduction rate of 9.1 during this period. Initial resistance to isoniazid and streptomycin decreased from respectively 13.9% and 12.3% in 1978-1979 to 4.2% and 5.8% by 1996. The level of multidrug resistance was low and stable, at 0.8% in 1996.

CONCLUSION

The experience of the Beijing tuberculosis control programme convincingly demonstrates that it is possible to improve the epidemiological situation rapidly in a low-income country, at very low cost and in a manner that is self-sufficient and sustainable.

Risk of tuberculosis infection and tuberculous meningitis after discontinuation of Bacillus Calmette-Guerin in Beijing

In Beijing, the notification rate of smear-positive tuberculosis (TB) has been below 20 per 100,000 since 1986, and continues to decline. To accurately measure the risk of TB infection in a population in which the results of tuberculin skin testing were not confounded by vaccination with Bacillus Calmette-Guerin (BCG), BCG vaccination at birth was discontinued from 1988 in Shun-yi County. In 1995, the prevalence of TB infection among 12,836 primary school children aged 6 to 7 yr and without BCG scars was 1.4%, giving an estimated annual risk of infection of 0.19% (95% confidence interval: 0.16 to 0.22%). The prevalence of TB infection in children aged 5 to 9 yr in Beijing in 1950 was 46%. The number of cases of tuberculous meningitis did not increase after discontinuation of BCG. We conclude that discontinuation of BCG had no detectable harmful effects, and that control of TB in Beijing has markedly reduced the prevalence of TB infection since 1950.

Behavior of lanthanides in countercurrent chromatography using dihexyl-N,N-diethylcarbamoyl methylene phosphonate as stationary phase

Counter-current chromatography is a real liquid-liquid chromatography. The retention volume of the solute can be calculated from the batch distribution ratio in organic separations. In the separations of metal ion, there are several complex and dissociation reactions involved in the two phases, and the retention volume cannot be always predicted from the batch distribution ratio. A mass transfer model is proposed in this paper and an expression of V(R) is derived. The retention volume of metal ion is determined not only by the batch distribution ratio but also by the mechanism of the extraction reaction. When 25% dihexyl-N,N-diethylcarbamoyl methylenephosphonate in cyclohexane is used as stationary phase and 2.91 mol/l HNO3 as mobile phase, the dynamic distribution ratios obtained from the chromatogram are not equal to but proportional to the batch distribution coefficients. These results are in agreement with the theoretical expression.

Estimation of burden of disease for smear-positive pulmonary TB and its infectivity

The study investigated the burden of smear-positive pulmonary TB and its infectivity, using DALY (Disability-Adjusted Life Year) as an indicator. An assumed cohort of 2000 cases was set up based on the age-specific incidence of 794 newly registered smear positive cases of TB in Beijing in 1994. Prognostic trees and model diagrams of infectivity under natural history and DOTS (Direct Observed Treatment, Short-course) strategy were established according to the epidemiological evidence. The results show that 29.6% of DALYs would be neglected if the burden caused by the infectivity was not considered. The results also show that DOTS strategy may reduce 97.3% of the number of potential cases infected, 92.9% of DALYs related to TB-patients themselves, and 99.9% of DALYs caused by TB's infectivity as well.

Molecular cloning of human Hic-5, a potential regulator involved in signal transduction and cellular senescence

By using differential display, we cloned the human counterpart of the murine gene Hic-5 from senescent human keratinocytes. The full-length cDNA contained a short GC-stretch proceeding a consensus Kozak sequence followed by a single open reading frame of 1338 bp encoding a 461-amino acid protein with a predicted molecular weight of 50 kDa. The expression of this gene was prominent in cells of epithelial origin but low or absent in lymphoid tissues and hematopoietic cells. The deduced protein contained four LIM domains at the carboxyl-terminal end and four LD motifs at the amino-terminal half, sharing high similarities with the focal adhesion protein paxillin. Hic-5 may therefore function, like paxillin, as a potential adapter for the recruitment of structural and signaling molecules to certain subcellular sites or in focal adhesions. Isolation of the genomic sequence revealed that the gene covered a segment of 6 kb and spanned 11 exons from the translation initiation site ATG to the termination signal TGA. Fluorescent in situ hybridization by using a human Hic-5 specific probe localized the gene to human chromosome 16p11.

[Antagonistic effects of melatonin on glutamate-induced neurotoxicity in rat hippocampal neurons]

The effects of glutamate (Glu) and melatonin (MEL) on the evoked populaion spike (PS) following stimulation of the schaffer collateral fiber were studied by extracellular recording technique in perfused slices of rat hippocampus: 5.0 mmol/L Glu decreased the PS peak values to 4.1% of control. This effect of Glu (5.0 mmol/L) on PS peak values was changed to 14.7%, 105.2% and 24.3% of control by 0.4, 0.5, 0.6 mumol/L of MEL. But when the interaction between MEL (0.5 mumol/L) and Glu (5.0 mmol/L) was entirely suppressed by CDP (0.5 mumol/L), the PS values reduced to zero. These results suggest that the inhibitory action of MEL on Glu-induced neurotoxicity may be mediated by 5-HT receptors.

Neural plasticity and emotional memory

Posttraumatic stress disorder is the pathological replay of emotional memory formed in response to painful, life-threatening, or horrifying events. In contrast, depression is often precipitated by more social context-related stressors. New data suggest that different types of life experiences can differentially impact biochemistry, physiology, anatomy, and behavior at the level of changes in gene expression. Repeated separation of neonatal rat pups from their mother results in many long-lasting alterations in biology and behavior paralleling that in depression, including hypercortisolism. The role of the amygdala in modulating emotional memory is highlighted, as well as some of its unique properties such as metaplasticity (i.e., the differential direction of long-term adaptation, either potentiation or depression) in response to the same input as a function of the prior history of stimulation. The implications of these emerging data on the physiological and molecular mechanisms underlying emotional memory emphasize the particular importance of prevention and early intervention.

Apoptosis of hippocampal neurons after amygdala kindled seizures

Seizure-induced neuronal damage may involve both excitotoxic and apoptotic (programmed cell death) mechanisms. In the present study, we used an amygdala kindled seizure model to study whether apoptotic cell death occurs. To evaluate apoptosis, we counted the numbers of cells that had DNA fragments labeled at the 3' end with digoxigenin using terminal transferase (ApopTag, Oncor). Additionally, the expression of Bax and Bcl-2, two genes associated with apoptotic cell death, was also measured following kindled seizures. We found that the number of ApopTag-positive cells in the hippocampus increased 30.4% after one kindled seizure and 82.5% after 20 seizures compared to sham controls. The ApopTag-labeled cells could be mainly interneurons of the hippocampal formation, although additional studies are required. Preferential vulnerability of inhibitory interneurons is consistent with previous studies on seizure-induced cell loss. These results, coupled with our findings that the ratio of Bax/Bcl-2 expression is increased in the hippocampus by seizures, suggest that apoptosis of hippocampal interneurons may lead to dysinhibition in the hippocampus and increased seizure susceptibility.

In situ investigation of Fas/FasL expression in chronic hepatitis B infection and related liver diseases

To evaluate Fas/FasL expression in hepatitis B virus-related chronic liver disease, liver biopsies from 44 such cases were studied immunohistochemically. FasL was detected in the infiltrating lymphocytes and both FasL and Fas were found in the hepatocytes. The Fas and FasL-positive cells were mostly found at the advancing edges of interphase hepatitis, and Fas/FasL expression was closely correlated with the inflammatory activity. Unexpectedly, FasL was also expressed in liver cirrhotic nodules, particularly in those with hepatocellular carcinoma with or without inflammation. These results suggest that the factors which induce hepatocyte transformation might also trigger FasL expression and promote FasL/Fas-mediated apoptosis.

Autolytic site mutant R105C of rat trypsin

The autolytic site Arg105 of rat trypsin was replaced with Cys by DNA site-directed mutagenesis method. Comparison of expression and purification of R105C trypsin along with the wild type and some other Arg105 mutants indicates that R105C trypsin could be expressed as well but with a lower expression level. It is unexpected that R105C trypsin has no detectable activity toward trypsin substrate TAME, quite different from the wild type and other Arg105 mutants. Native gel electrophoresis analysis indicates that R105C trypsin has a similar mobility rate to that of wild type trypsin. FPLC also gives similar retaining time. The loss of activity of R105C trypsin may result from the conformational change around active site, but not the dimer formation.

Anterograde transport of endogenous brain-derived neurotrophic factor in hippocampal mossy fibers

Neurotrophic factors such as brain-derived neurotrophic factor (BDNF) are assumed to provide trophic support via a target-derived, retrograde mechanism of action. However, recent studies suggest that neurotrophic factors can act in an autocrine fashion and perhaps even in an anterograde direction similar to neurotransmitters. To further explore this hypothesis, we compared the neuroanatomical pattern of BDNF mRNA and protein in response to electroconvulsive seizures (ECS) or kainic acid-induced seizure activity. Using in situ hybridization, we found that chronic ECS induced BDNF mRNA predominantly in the granule neurons of the dentate gyrus. However, immunohistochemistry with an anti-BDNF antibody revealed that ECS increased endogenous BDNF protein in the mossy fibers, which are composed of axons projecting from the granule neurons of the dentate gyrus to the CA3 pyramidal layer of the hippocampus. Kainic acid administration (10 mg/kg, i.p., once) was used to lesion CA3 neurons selectively, as these are a possible retrograde source of BDNF protein in mossy fibers. Three weeks later, a prolonged elevation of BDNF mRNA in granule neurons, but not elsewhere in hippocampus, was accompanied by an increase in BDNF protein in the mossy fibers. These results suggest that BDNF was transcribed and translated in granule neuron cell bodies but transported in an anterograde direction to provide trophic support of CA3 pyramidal neurons.

Effect of tripterine on collagen-induced arthritis in rats

AIM

To study the therapeutic effect of tripterine (Tri) on collagen-induced arthritis (CIA).

METHODS

Collagen type II (Col) 1.5 mg was injected intradermally to induce CIA in rats. Hind paw volumes of rats were measured with a water displacement method. The serum anti-collagen antibody was measured by an enzyme-linked immunosorbent assay. Delayed hypersensitivity was reflected by skin response to Col. Interleukin-1 (IL-1) and interleukin-2 (IL-2) activities were evaluated by [3H]TdR uptake. Joint was evaluated histologically.

RESULTS

Tri 15 and 30 mg.kg-1.d-1 given i.g. to rats 3 d after the first sign of arthritis reduced inflammatory swelling, suppressed humoral and skin response to Col, inhibited IL-2 and IL-1 production, reduced pathological progression of joint.

CONCLUSION

Tri has a therapeutic effect on CIA.

Cloning of the human orphan receptor germ cell nuclear factor/retinoid receptor-related testis-associated receptor and its differential regulation during embryonal carcinoma cell differentiation

We have cloned a cDNA encoding the full-length coding region of the human homologue of the germ cell nuclear factor (GCNF)/retinoid receptor-related testis-associated receptor (RTR), from a human testis cDNA library. The amino acid sequence of human GCNF/RTR is highly homologous to that of the mouse GCNF/RTR. The largest difference between the two homologues is a 15 amino acid deletion in the human GCNF/RTR at amino acid 47. The GCNF/RTR gene was localized on human chromosome 9. Northern blot analysis using poly(A)+ RNA from different human tissues showed that GCNF/RTR mRNA is most abundantly expressed in the testis. GCNF/RTR was also highly expressed in embryonic stem cells and embryonal carcinoma cells but repressed in its differentiated derivatives. Induction of differentiation of mouse embryonal carcinoma F9 cells and human embryonal carcinoma NTERA-2 clone D1 (NT2/D1) cells by all-trans retinoic acid was accompanied by a down-regulation of GCNF/RTR. Our observations suggest that GCNF/RTR plays a role in the control of gene expression in early embryogenesis and during spermatogenesis.

Lipofectin-facilitated transfer of cholecystokinin gene corrects behavioral abnormalities of rats with audiogenic seizures

To evaluate the potential for lipofectin-mediated central nervous system gene transfer, the plasmid coding for cholecystokinin was administered intracerebroventricularly to rats, which have congenital audiogenic seizures and high responses to peripheral electric stimulation-induced analgesia. Previous studies had shown that low brain cholecystokinin levels may be the neurochemical variable of rat's audiogenic seizure and high responses to the analgesia because cholecystokinin is an anticonvulsant and anti-opioid neuropeptide. Gene transfer of cholecystokinin corrected the increased susceptibility to audiogenic seizures and the high responses to analgesia for about one week. Similar administration of plasmid expressing beta-galactosidase indicated that the vector mainly transfected ependymal cells lining the ventricle and pia mater cells. The increased cholecystokinin messenger RNA and immunoreactivity in the hippocampus following stereotactic intrahippocampal administration of cholecystokinin plasmid was also demonstrated with in situ hybridization and immunohistochemistry techniques. These results suggest that lipofectin-mediated gene transfer will be useful for studies of brain function, the modification of behavior and gene therapy for central nervous system disorders.

Rats with decreased brain cholecystokinin levels show increased responsiveness to peripheral electrical stimulation-induced analgesia

Using the P77PMC strain of rat, which is genetically prone to audiogenic seizures, and also has decreased levels of cholecystokinin (CCK), we examined the analgesic response to peripheral electrical stimulation, which is, in part, opiate-mediated. A number of studies have suggested that CCK may function as an antagonist to endogenous opiate effects. Therefore, we hypothesized that the P77PMC animals would show an enhanced analgesic response based on their decreased CCK levels producing a diminished endogenous opiate antagonism. We found that the analgesic effect on tail flick latency produced by 100 Hz peripheral electrical stimulation was more potent and longer lasting in P77PMC rats than in control rats. Moreover, the potency of the stimulation-produced analgesia correlated with the vulnerability to audiogenic seizures in these rats. We were able to block the peripheral electrical stimulation-induced analgesia (PSIA) using a cholecystokinin octapeptide (CCK-8) administered parenterally. Radioimmunoassay showed that the content of CCK-8 in cerebral cortex, hippocampus and periaqueductal gray was much lower in P77PMC rat than in controls. These results suggest that low CCK-8 content in the central nervous system of the P77PMC rats may be related to the high analgesic response to peripheral electrical stimulation, and further support the notion that CCK may be endogenous opiate antagonist.

Amygdala-kindled seizures increase the expression of corticotropin-releasing factor (CRF) and CRF-binding protein in GABAergic interneurons of the dentate hilus

Kindling, a model of temporal lobe epilepsy, induces a number of neuropeptides including corticotropin-releasing factor (CRF). CRF itself can produce limbic seizures which resemble kindling in some aspects. However, tolerance to the convulsant effects of CRF develops rapidly. Hypothetically, this could be explained should seizures also induce the CRF-binding protein (CRF-BP), which has been postulated to restrict the actions of CRF. Therefore, in the present study, we used in situ hybridization to examine the effects of amygdala-kindled seizures on the mRNA levels of CRF and CRF-BP. Kindled seizures markedly elevated CRF and CRF-BP in the dentate gyrus of rats. CRF and CRF-BP were induced almost exclusively in GABAergic interneurons of the dentate hilus. The CRF and CRF-BP interneurons also expressed neuropeptide Y but not cholecystokinin. CRF appeared to have an excitatory role in the dentate gyrus as it decreased the afterhyperpolarization of dentate granule neurons. These results suggest that CRF may contribute to the development of amygdala kindling. However, the compensatory induction of CRF-BP may serve to limit the excitatory effects of CRF in the dentate gyrus.