A robust backpropagation learning algorithm for function approximation

The backpropagation (BP) algorithm allows multilayer feedforward neural networks to learn input-output mappings from training samples. Due to the nonlinear modeling power of such networks, the learned mapping may interpolate all the training points. When erroneous training data are employed, the learned mapping can oscillate badly between data points. In this paper we derive a robust BP learning algorithm that is resistant to the noise effects and is capable of rejecting gross errors during the approximation process. The spirit of this algorithm comes from the pioneering work in robust statistics by Huber and Hampel. Our work is different from that of M-estimators in two aspects: 1) the shape of the objective function changes with the iteration time; and 2) the parametric form of the functional approximator is a nonlinear cascade of affine transformations. In contrast to the conventional BP algorithm, three advantages of the robust BP algorithm are: 1) it approximates an underlying mapping rather than interpolating training samples; 2) it is robust against gross errors; and 3) its rate of convergence is improved since the influence of incorrect samples is gracefully suppressed.

Primary hydatid cyst in the soft tissue of the face: an exceptional occurrence

To emphasize that solitary hydatid cyst can be localized in the soft tissue and present as a soft tissue mass even in an unusual site like face, we report the case of a 42-year-old male patient presenting with a slowly growing mass in right temporal region. Computed tomography (CT) scan showed an encapsulated mass with multiple cysts. Histopathological examination revealed the characteristic findings, which were consistent with soft-tissue hydatid disease. In the absence of visceral organ involvement, this is the first reported case of a primary subcutaneous hydatid cyst in the skin of face in India. In the English literature, only one case of this kind has been reported till date. When imaging methods confirm cystic nature of a swelling, even in unusual sites, one should always keep a possibility of hydatid cyst and manage accordingly during surgery to avoid precipitation of acute anaphylaxis.

Adherence to tuberculosis treatment: lessons from the urban setting of Delhi, India

The Revised National Tuberculosis Control Programme (RNTCP), which incorporated the WHO DOTS strategy was introduced in India in the mid-1990s. An operational research project was conducted between 1996 and 1998 to assess the needs and perspectives of patients and providers in two chest clinics in Delhi, Moti Nagar and Nehru Nagar, during the introduction of the new strategy. This paper reports on the findings of the project, concentrating on information collected from 40 in-depth interviews with patient defaulters and from non-participant observations in clinics and directly observed treatment centres. In Moti Nagar chest clinic, 117 of 1786 (6.5%) patients and 195 of 1890 (10%) patients in Nehru Nagar left care before their treatment was complete. It was argued that the reasons for default stem from a poor correlation between patient and programme needs and priorities, and from particular characteristics of the disease and its treatment. Patient needs that were not met by the health system included convenient clinic timings, arrangements for the provision for treatment in the event of a family emergency and provision for complicated cases like alcoholics. The problems facing the provider were poor interpersonal communication with the health staff, lack of attention and support at the clinic, difficulty for patients to re-enter the system if they missed treatment and, in certain areas, long distances to the clinic. Problems related to diseases were inability of the staff to deal with drug side-effects, and patients' conception of equating well-being with cure. Simple, practical measures could improve the provision of tuberculosis (TB) treatment: more flexible hours, allowances for poor patients to reach the clinics and training health care staff for respectful communication and monitoring drug side-effects. The findings indicate a need to rethink the label of 'defaulter' often given to the patients. The important areas for future operational research is also highlighted.

TB control, poverty, and vulnerability in Delhi, India

The Revised National Tuberculosis Control Programme (RNTCP), based on the World Health Organization's DOTS strategy,* was introduced in India in the mid-1990s. This paper reports the findings from operational research studies in two pilot sites in New Delhi from 1996 to 1998. A variety of operational research methods were used, including semi-structured interviews, focus group discussions, non-participant observations and collection of data from the tuberculosis registers. The cure rates for the clinics were 71 and 75% with a default rate of 6 and 11%, respectively. An important finding was that health workers screened patients to determine their ability to conform to the direct observation of treatment element of the RNTCP. If the health worker was confident that the patient would comply and/or be easy to trace in the community in the event of 'default', they were provided with short-course treatment under the RNTCP. Other patients, largely those who were in absolute poverty, socially marginalized, itinerant labourers, poorly integrated in the city, were put on standard tuberculosis (TB) treatment as for the previous National TB Programme. The programme was evidently excluding the most vulnerable from the best available care. These findings demonstrate the potential dangers of target-driven programmes where there is an absence of support to both frontline health workers and patients. The paper also highlights the importance of operations research in helping to identify problems within TB programmes.

Experimental studies on waste paper pulp biodegradation

In continuation of their studies on Biodegradation of cellulosic waste materials, the authors have presented their experimental data on biodegradation on waste paper pulp. Greater efficiency in the cow dung and M3 culture experimental setups have been pointed out and discussed. Necessity of detailed data evaluation of temperature, pH, dry weight, cellulose, protein, carbohydrate, Nitrate, Phosphate & Potassium levels is suggested. Derivation of %, absolute and increase/decrease % of BOO, COD and VS have been pointed out for the first time in solid waste Biodegradation. Further data evaluation and derivation of critical reaction rate kinetics have been recommended for further studies in solid waste-degradation to achieve quicker Bioconversion of cellulosic wastes into compost.

Cold reactive lymphocytotoxic antibodies in pulmonary tuberculosis: correlation with disease activity and HLA

Cold reactive lymphocytotoxic antibodies (LCA) are more reactive in cold than at 37 degrees C and occur following infection, immunization or vaccination and in various autoimmune diseases. In the present study, LCA activity against T and B-lymphocytes has been investigated in patients with pulmonary tuberculosis (PTB), their various clinical sub-groups and consanguineous relatives. Further, the relevance of HLA factors in LCA activity was analyzed. The sera from 144 PTB patients, 52 family contacts and 52 healthy individuals were tested for presence of LCAs by a modified two-stage NIH microlymphocytotoxicity assay. A significant increase in LCA activity against both T (32.6% vs 5.7%, P < 0.0001) and B (59.7% vs 13.4%, P < 0.0000001) cells was observed in PTB patients as compared to healthy controls. There was no correlation between serum LCA activity and sputum acid-fast bacilli status. However, only B cell LCAs revealed significant increase in parallel to disease advancement as assessed by X-ray chest examination. Further, LCA activity was more pronounced in drug responders than drug failure group of patients. No significant difference in the distribution of HLA class I and class II antigens was observed between LCA positive and LCA negative patients. However, panel cells carrying HLA-A1, -A11 and -DR3 were often found reactive in LCA positive patient sera. In household family contacts, LCAs were significantly increased only against B cells as compared to healthy controls (38.4% vs 13.4%, P < 0.01). This study suggests that Mycobacterium tuberculosis infection/exposure could account for the occurrence of LCAs in pulmonary tuberculosis and the strength of these antibodies is related to disease severity and the extent of lung involvement.

Knowledge, attitudes and practices of newly diagnosed sputum positive cases of pulmonary tuberculosis

Lack of awareness of risk posed to the community by a sputum positive case of Pulmonary Tuberculosis (PTB) is an impediment in the control of Tuberculosis. A study involving 212 newly diagnosed sputum positive patients aged 15 years or more, revealed that only 9% of the patients knew correctly the cause of PTB. Knowledge about mode of spread of the disease was not known to 49% of patients. Awareness regarding the investigations like chest X-ray and sputum examination was high as 70% but utility of sputum examination was known to only 29% of the patients. Awareness of harmful sequelae of inadequate and incomplete treatment was as high as 93% but knowledge per se of adequate duration of treatment was poor in a half (50%) of the subjects. Attitude towards domiciliary treatment was generally positive (88%) Practices regarding safe sputum disposal and preventive measures practised in the families were poor in nearly two third's of patients. Health education efforts need to be strengthened to create better awareness of these important aspects of tuberculosis diagnosis, treatment and control.

Awareness about tuberculosis among nurses working in a tuberculosis hospital and in a general hospital in Delhi, India

SETTING

A tuberculosis institute and a general hospital in Delhi, India.

OBJECTIVE

To investigate the awareness of nurses about tuberculosis and to evaluate the differences in awareness, if any, between nurses working in tuberculosis and those in a general hospital.

DESIGN

A pretested questionnaire survey was performed on 213 nurses.

RESULTS

The present study showed that a substantial number of nurses have inadequate knowledge regarding causative factors, the importance of sputum examination, correct doses of routinely used short-course chemotherapy drugs, the minimum duration of short-course chemotherapy, instructions at discharge, and health education for patients and family members. If responding correctly to 75% of the questions asked is taken as the criterion for satisfactory awareness, only 40.2% of tuberculosis nurses and 10.7% of general hospital nurses had a satisfactory level of awareness. There was no effect of increasing age or years of experience on the level of awareness.

CONCLUSIONS

There is a general lack of knowledge regarding various aspects of tuberculosis among nurses. Active interventions are required to improve awareness for a better implementation of the revised national tuberculosis control programme in India.

Survey of knowledge, attitudes and practices for tuberculosis among general practitioners in Delhi, India

SETTING

Random survey of knowledge, attitudes and practices (KAP) for tuberculosis among private practitioners (PPs) in Delhi, India, in 1995.

OBJECTIVE

To investigate the KAP of private practitioners for tuberculosis in Delhi where the Revised National Tuberculosis Programme (RNTP) is being field tested.

DESIGN

A pre-tested questionnaire survey was performed among 204 doctors attending updates/seminars on tuberculosis in various parts of Delhi.

RESULTS

In a suspected case of tuberculosis, sputum examination was advised by only 12% of the PPs, while 89.5% would recommend chest X-ray. For treating tuberculosis 187 PPs were using 102 different regimens, and only 29.4% PPs were using the regimen recommended by the RNTP; 51.3% PPs were over-treating their patients. Only 23.5% of PPs requested sputum examination before the end of treatment, while 35.5% depended on X-ray clearance with clinical improvement. Only 19.5% of PPs emphasized the importance of regular treatment for their patients.

CONCLUSION

Among PPs there is marked reliance on X-ray; sputum examination is being neglected for initial diagnosis, treatment monitoring and as a criterion for stopping treatment. The majority of PPs are not aware of, or are not prescribing, the treatment regimen recommended by the RNTP, and the majority of patients are being over-treated. There is a lack of emphasis on proper health education. PPs need more training, and more collaborative efforts are required between public health facilities and practising doctors for national control of tuberculosis.

Genotypic detection of mutations in rifampicin resistant clinical isolates ofMycobacterium tuberculosis

The resistance of majority ofM. tuberculosis strains to rifampicin a key drug in the tuberculosis therapy, has been cause of major alarm world-wide. Such an association of strain with the drug takes a long time i.e. 2-3 months. We have modified a method for rapid detection of rifampicin resistant strains by screening them through PCR-SSCP.We have identified mutations in rpo, β region of the gene encoding, β sub-unit of RNA polymerase in rifampicin resistant 67 clinical isolates ofM. tuberculosis. Mutations were screened in these isolates by single strand confirmation polymorphism (SSCP). When DNA sequencing data was compared with the result of SSCP analysis, direct PCR sequencing results were more easily interpreted and contatined more sequence dependent information. These findings provide the basis for rapid detection of rifampicin esistance, a marker of multidrug resistance.

HLA class I profile in Asian Indian patients with pulmonary tuberculosis

HLA class I antigen profile was studied in 153 unrelated patients with pulmonary tuberculosis (PTB), 40 family contacts and 289 healthy individuals by the NIH microlymphocytotoxicity test to find out the role of HLA-A, -B, -C alleles in influencing susceptibility to PTB and its various clinical groups. HLA-A2 was found to be significantly increased in the total patient group as compared to controls (38.6% vs 26.3%, p < 0.01, RR = 1.76). The increase of HLA-A2 was more pronounced in the sputum negative patients (59.4%, pc < 0.001, RR = 4.1) suggesting its possible role in the mediation of CD8+ suppressor T cell activity against Mycobacterium tuberculosis, resulting in the development of limited disease in these patients. Further, HLA-B18 was found to be decreased in patients as compared to controls (2.6% vs 7.3%, p < 0.05, RR = 0.34). None of the class I antigens was associated with the dynamics of chemotherapy or disease severity as assessed by the extent of lung involvement on chest X-ray examination.

Anti-IgG autoantibodies and possible immune regulatory mechanisms in patients with pulmonary tuberculosis

SETTING

Anti-Ig antibodies are known to have important clinical and biological implications.

OBJECTIVES

To determine naturally occurring anti-F(ab')2 gamma and anti-Fc gamma antibodies in patients with pulmonary tuberculosis (PTB) in relation to various clinical manifestations and human leukocyte antigen (HLA).

DESIGN

Antibodies to F(ab')2 and Fc portions of IgG were detected in the sera of normal healthy individuals (n = 41), patients with pulmonary tuberculosis (n = 50) and their household family contacts (n = 20) using an enzyme immuno assay (EIA) system.

RESULTS

As compared to controls (0.110 +/- 0.01 optical density [OD]), the levels of anti-F(ab')2 gamma were significantly increased in PTB patients (0.998 +/- 0.08 OD, P < 0.0001) and in their contacts (0.486 +/- 0.04 OD, P < 0.001) suggesting that the occurrence of these autoantibodies is related to infection/exposure to Mycobacterium tuberculosis. Anti-F(ab')2 gamma antibodies were significantly increased in both sputum positive and negative patients (P < 0.0001) and no deviation was observed between these two groups. The levels of these antibodies were positively correlated with disease severity assessed by chest X-ray. The drug failure patients had higher activity of anti-F(ab')2 gamma than drug responders and no impact of anti-tuberculosis chemotherapy was observed. A statistically significant increase of anti-F(ab')2 gamma levels (1.25 +/- 0.21 OD) was observed in HLA-DR2 positive patients as compared to the DR2 negative groups (1.02 +/- 0.09 OD), P < 0.01. No deviation was observed in the levels of anti-Fc gamma levels between controls and any group of PTB patients.

CONCLUSION

The present data suggests that the elevated levels of anti-F(ab')2 gamma antibodies in PTB patients represent an anti-idiotypic antibody response to anti-M. tuberculosis antibody caused by an immune imbalance following M. tuberculosis infection.

Correlation of serum interleukin-2 receptor-alpha levels with clinical manifestations in pulmonary tuberculosis

SETTING

The analysis of serum levels of soluble interleukin-2 receptor alpha (sIL-2R-alpha) is an indirect method of studying the in vivo state of immune activation, particularly in patients with pulmonary tuberculosis (PTB) where the disease is associated with cellular immune reactions.

OBJECTIVE

To quantitate the serum sIL-2R-alpha in patients and correlate with disease activity.

DESIGN

The levels of sIL-2R-alpha were determined using ELISA in serum samples from untreated patients with PTB (n = 107), 30 of whom were later tested during treatment, household family contacts (n = 38), and healthy controls (n = 22).

RESULTS

Concentrations of sIL-2R-alpha were significantly higher in PTB patients than in controls (2845 +/- 187 vs 1217 +/- 80 pg/mL, P < 0.0001), and were even more pronounced in the sputum positive (3200 +/- 148 pg/mL) and treatment failure (3335 +/- 196 pg/mL) groups of patients. However, in household family contacts, the sIL-2R-alpha levels were found to be similar to those of healthy controls. The sIL-2R-alpha levels correlated positively with disease activity as assessed by roentgenographic findings. In six of the 16 responder patients, the sIL-2R-alpha levels fell from 3228 +/- 144 pg/mL to 1497 +/- 131 pg/mL (P < 0.0001) after 3 months of successful treatment with anti-tuberculosis drugs. However, no significant change was observed in the treatment failure patients even after one year of chemotherapy with second-line drugs.

CONCLUSION

These studies indicate that determination of serum concentrations of sIL-2R-alpha is a sensitive and specific method for monitoring disease activity in terms of T cell activation in pulmonary tuberculosis.

Polymerase chain reaction--based sequence-specific oligonucleotide hybridization analysis of HLA class II antigens in pulmonary tuberculosis: relevance to chemotherapy and disease severity

HLA antigens were studied by serology and polymerase chain reaction-based sequence-specific oligonucleotide hybridization techniques in 153 patients with pulmonary tuberculosis (PTB) and 289 healthy controls. HLA-DR2 was present more frequently in PTB patients than in controls (51% vs. 36.3%; corrected P[Pc]=.029, relative risk [RR] = 1.8). The DR2 association was stronger in patients in the drug-failure group (n=56; Pc=.000012, RR=3.7) than in healthy controls and in patients in the drug-responder group. No significant deviation was observed in HLA allelic frequencies in various patient groups, as determined by radiographs of lung lesions. Molecular subtyping of DR2 revealed that the bulk of the allele was DRB1*1501 and DRB1*1502 in patients and controls. There was no skewing of the frequency of these molecular subtypes of DR2 in patients, suggesting that the whole DR2 molecule or its closely linked gene(s) may be involved in governing patient susceptibility to PTB and, particularly, development of the severe drug-resistant form of the disease.

Epididymal histoplasmosis diagnosed by isolation of Histoplasma capsulatum from semen

An autochthonous case of epididymal histoplasmosis masquerading as tuberculosis in a 55-year-old male patient is reported from India. It was diagnosed by culture of Histoplasma capsulatum from semen and by demonstration of the fungus upon re-examination of epididymal biopsy sections previously misinterpreted as tuberculous granuloma. The patient's main complaints were painful epididymal swelling, occasional fever and cough. He was treated successfully by excision of epididymis and vas deferens combined with amphotericin B therapy. This is believed to be the first case of epididymal histoplasmosis to be reported outside the American continent and the fourth of its type reported in the English literature. The case is also noteworthy in that H. capsulatum was isolated for the first time from semen, and it underlines the importance of mycological culture of semen specimens for diagnosis of genitourinary infections of obscure etiology.

Endemicity of cholera among rural areas of Loni, Ahmednagar district of Maharashtra

A total of 130 Vibrio cholerae strains isolated during November 1989 to December 1992 from the rural population of Loni areas--Ahmednagar district of Maharashtra were characterised. Of these isolates, 124 were El tor vibrios serotype Ogawa, and 6 were El tor vibrios serotype Inaba. One hundred twenty two strains belonging to T4 phage, while 8 strains of El tor vibrio serotype Ogawa were untypable. All the strains isolated, showing haemolytic and non-haemolytic colony variants of El tor V. cholerae, and had resistance of one or more antibiotics. Maximum incidence was observed in November-December, the illness had a mild onset and no fatality was reported.

G-6PD deficiency in malaria endemic areas of Udaipur District in Rajasthan

Nine thousand four hundred thirty three pyrexial cases were screened for the evidence of Malaria and Glucose-6-phosphate dehydrogenase deficiency among the rural tribal population of seven primary health centres in the malarial endemic areas of Udaipur District in Southern Rajasthan. One thousand four hundred five (P. Falciparum 831 and P. Vivax 574) cases were positive for malaria and 170 for G-6PD deficiency. Incidence of G-6PD deficiency in malaria, when compared to the non-malarial cases revealed statistically insignificant alterations (X2 is calculated to 0.1299 which for 1 degree of freedom gives P > 0.05).

Prevalence of hepatitis surface antigen among rural population of Loni area in Ahmednagar district of Western Maharashtra

Three hundred and fifty three subjects among the rural population of Loni area admitted in the hospital, and 188 medical staff members working in the Rural Medical College and Hospital, Loni, were screened for the presence of HBsAg. Reveresed passive haemagglutination assay was used for screening; it showed an HBsAg positivity rate of 21.8% and 15.8% among hepatitis and non hepatitis cases respectively, and 1.2%, 0% and 4.2% among medical students, doctors and nursing staff respectively. A high HBsAg positivity rate has been observed in the rural population of Loni area.

Complement activation in pulmonary tuberculosis

The alterations in serum/plasma levels of total haemolytic complement activity (CH50), complement components C3 and C3d, and circulating immune complexes (CICs) in patients with pulmonary tuberculosis were analysed in relation to the severity of disease and treatment status. The mean levels of CH50, C3, C3d and CICs were significantly higher in untreated than treated patients and in normal controls. In the untreated group, the level of each of these four parameters except C3d was significantly higher in patients with far advanced disease than in those with moderately advanced disease, whereas the difference between treated patients and normal controls was not statistically significant for any of the four parameters tested. There were statistically significant correlations between levels of CICs and both C3 and C3d in the untreated tuberculosis patients. However, the correlations for the same parameters were not significant when treated patients were considered. The CH50 levels in tuberculosis patients suggest a functional classical complement pathway, which is essential for immune complex solubilisation. High C3d level in untreated patients is indicative of increased complement activation, which in turn shows significant correlation with levels of CICs. It appears that the intact and elevated complement proteins and their proper activation by CICs prevents tuberculosis from becoming a typical immune complex disease.

Restriction endonuclease analysis of DNA in sickle cell lesions among tribals of Bihar, Madhya Pradesh, Gujarat & Rajasthan

Restriction endonuclease analysis of DNA was undertaken in blood samples from individuals who were normal (110), had sickle cell trait (44) and homozygous sickle cell disease (6) from the tribal populations of Bihar, Madhya Pradesh, Gujarat and southern Rajasthan. DNA was prepared from all the blood samples and processed for restriction enzyme digestion, agarose electrophoresis, prehybridization, Nick-translation hybridization and autoradiography. A polymorphic HpaI restriction endonuclease recognition site on the 3' side of the beta-globin gene was used to analyse to determine the beta-globin gene mutant S. It was found that mutation has resulted within the normal 7.6 Kb HpaI fragment among the tribal populations studied. On comparing the results with those from Middle East and East Africa it appears that the sickle gene mutation in India, Saudi Arabia and Kenya arose separately from that in West Africa.

Benzo(a)pyrene hydroxylase activity in human bronchial mucus

Sputum collected from patients with respiratory diseases were examined for presence of benzo(a)pyrene hydroxylase (BPH) activity. The human bronchial mucus used in these studies had significant capability to metabolize benzo(a)pyrene. Clarification of the sputum by agents such as N-acetylcysteine or pancreatin in presence of antibiotics was found to be essential for the detection of BPH activity. In vitro incubation of the clarified human bronchial mucus with benzoflavone caused inhibition, while 7,8-dimethyl-benzanthracene induced BPH enzyme activity.

Sickle cell and thalassaemic genes in Libya

An electrophoretic study of haemolysates from 1350 subjects from the indigenous population of Libya was carried out to find the incidence of abnormal haemoglobins and thalassaemia. Sickle cell disease was detected in five (0.37%), sickle cell trait in 61 (4.51%), sickle cell thalassaemia in three (0.21%), homozygous betathalassaemia in 16 (1.20%), heterozygous delta-beta thalassaemia in 25 (1.85%) and heterozygous beta-thalassaemia in 105 (7.77%). The incidence of the sickle cell gene is low, but that of the thalassaemic gene appears to be high in the Libyan population which is racially mixed, containing Arab, Mediterranean and Negroid types.