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Biomedical subjects

A M Samuel

Publications and source records attributed to A M Samuel.

At least 55 records · Page 3Linked to original sources
PubMed1993

T lymphocytes in pulmonary tuberculosis.

T cells and their sub-populations were evaluated with respect to reactive, intermediate and unreactive forms of tuberculosis as classified by Lenzini. Significant CD4 lymphopenia and a reduction of CD4/CD8 ratios were found in patients with reactive tuberculosis. It was observed that there was a B lymphocytosis, CD8 lymphocytosis and a reduction of CD4/CD8 ratio in patients with intermediate and unreactive forms of tuberculosis. The T lymphocytes and CD4 subset were unchanged. There was no significant difference in the lymphocytes and sub-populations among the intermediate and unreactive groups.

Adult↗
PubMed1993

Bone scans in neuroblastoma.

Eighty-Six patients of neuroblastoma ranging in age from four months to 15 years were studied with 99m Tc-MDP for total skeletal survey over a period of seven years (1983-1990). The diagnosis of neuroblastoma was based on bone marrow examination, FNAC, lymph node biopsy, histopathology. Bone imaging was performed three hrs. after intravenous administration of 99m Tc-MDP. Out of 86 patients, 45 patients had positive bone scan showing osseous concentration in 122 sites and extraosseous concentration in 34 sites. Seven patients had liver metastases. None of these liver metastases showed concentration of MDP. Fourteen patients underwent surgery for the primary tumour at the time of bone scanning. Ten patients were studied at the time of follow up, of which four patients showed good response as bony metastases were not demonstrated on bone scintigraphy and X-rays. In conclusion, bone scan is an useful test in neuroblastoma in delineating the bony metastases and also in assessing the efficacy of chemotherapy in these patients.

Abdominal Neoplasms↗
PubMed1992

Radioimmunoscintigraphic approach for the in vivo detection of tuberculomas--a preliminary study in a rabbit model.

Radioimmunoscintigraphic approach could provide a viable non-invasive alternative for the diagnosis of deeply situated tuberculomas. We have evaluated this in a rabbit model constructed to give a characteristic localized tubercular lesion, with complimentary morphological, histological and antigenic profiles. 131I-anti Myobacterium bovis (BCG) antibody was shown to localize at the lesion, where as 131I-bovine serum albumin and 99mTc-red blood cell scans were negative. The clearance of intradermally-injected tuberculous antigen could be traced into ascending lymph nodes using 131I-anti M. bovis (BCG) antibody.

Animals↗
PubMed1992

A study of tubercular antigen and antibody in childhood tuberculosis.

A radioimmunoassay for the detection of tubercular (TB) antigen (Ag) and antitubercular antibody (Ab) was evaluated for the serodiagnosis of childhood tuberculosis. Children with primary complex, progressive primary complex, miliary tuberculosis, and calcified lung lesions without clinical evidence of active tuberculosis were studied. Significantly elevated levels of TB Ag and TB Ab isolated from the circulating immune complexes were obtained in primary, progressive primary, and miliary tuberculosis patients as compared to controls (P less than 0.01). The majority of patients with calcified lung lesions and without active tuberculosis demonstrated high levels of antibody. It was observed that elevated levels of TB Ag and/or antibodies were present in 54 per cent of patients with primary complex, 94 per cent of patients with progressive disease and 69 per cent of patients with miliary tuberculosis. It is possible that is suspected patients with the above mentioned diseases, a diagnosis can be established by using these techniques.

Antibodies, Bacterial↗
PubMed1992

Isotope angiography and blood pool imaging as a procedure for assessing radiation-induced injuries to the hands.

The authors discuss radioisotope angiography and blood pool imaging for assessing radiation-induced injuries to the hands and the deterioration or improvement in status during follow-up. Two industrial radiographers in two separate accidents were exposed to 22 Ci to 25 Ci of a Co-60 for 2 to 3 minutes each in February 1985. Subsequently, besides routine clinical examinations and other tests, they underwent a series of amputations and grafts in the digits of the hands. A first-pass study with Tc-99m sodium pertechnetate followed by delayed RBC labeled blood pool imaging was performed in September 1988 in both patients. Both had a reduced flow of tracer to the more affected hand and the affected digits. A repeat study performed in March 1989 revealed improvement in perfusion to the more affected hand in the first patient and no change in the second. Delayed blood pool imaging did not reveal any change. The improvement in flow also coincided with the reduction of pain in the affected digits of the first patient. The authors conclude that isotope angiography followed by delayed blood pool imaging is a simple, noninvasive procedure to assess radiation-induced damage to extremities and to evaluate deterioration or improvement during follow-up.

Accidents, Occupational↗
PubMed1991

Differentiated thyroid carcinomas in children and adolescents.

An analysis of differentiated thyroid carcinomas in children and adolescents revealed that the incidence was 3.05% of total number of patients with differentiated thyroid cancers in all age groups. There was a female preponderance. The incidence of papillary, follicular and papillary with follicular elements was equal. There were no papillary carcinomas observed in children younger than 10 years. The predominant mode of presentation was a solitary nodule of thyroid and some of them had associated cervical adenopathy. A considerable number presented with only cervical adenopathy. The incidence of nodal metastases was 50% at time of presentation and lung involvement was present in 15% of children at the time of diagnosis. Radioiodine treatment was given in 70% of children. Ablation was achieved in 86% of patients given two doses of radioiodine (200 millicuries). The more resistant cases were those with lung and nodal metastases. There was complete ablation in 100% with only residual thyroid tissue, 83% in those with associated nodal metastases, and 57% in those with lung involvement. Average duration of follow-up was 10.3 years (range, 2 to 19 years). Recurrence rate or relapse was observed in 8.5% and was in the regional nodes. There was no recorded mortality due to the disease.

Adenocarcinoma↗
PubMed1991

Regional distribution study of brain perfusion and metabolic agents in normal and tumour bearing rat brains using autoradiographic technique.

Regional distribution of brain perfusion imaging agents, [131I]N,N,N'-trimethyl-N'-[2-hydroxy-3-methyl-5-iodobenzyl]1,3 propanediamine (HIPDM) and [131I]-N-isopropyl-p-iodoamphetamine (IMP), was compared with the distribution of patterns of [14C]L-methionine and [14C]D-glucose in normal and tumour bearing rat brains using autoradiographic technique. There was higher concentration of the radiopharmaceutical in grey than white matter in normal rat brain. Autoradiographs of brain tumour sections showed very low uptake of [131I]HIPDM and [131I]IMP as compared to normal brain tissue. There was moderate concentration of [14C]D-glucose and avid uptake of [14C]L-methionine in tumours. Autoradiographic study is useful for evaluating distribution patterns of radiopharmaceuticals.

Amphetamines↗
PubMed1991

Total and free thyroid hormone levels in chronic renal failure.

The levels of serum total thyroxine (TT4), triiodothyronine (TT3), free T3, (FT3) free T4 (FT4) and thyrotropin (TSH) were measured in 127 clinically euthyroid patients with varying grades of chronic renal failure (CRF); and 97 healthy individuals. They were grouped as: Group I containing 93 patients on conservative management; Group II containing 34 patients on regular dialysis therapy; and Group III (normals). Group I patients showed significant decrease in TT3, TT4 and FT3 levels (p less than 0.001) as compared to Group III, whereas FT4 and TSH values in group I were not significantly altered. TT3, TT4 and FT3 levels reduced as the severity of renal damage increased. Variations in TT3, TT4, FT3, FT4 and TSH levels in Group II patients were similar to those in Group I, except for a decrease in TSH levels (p less than 0.05) as compared to normals. Several thyroid function tests are abnormal in CRF patients, however, finding of normal FT4 and TSH levels would indicate functional euthyroid status.

Humans↗
PubMed1991

Determination of free thyroxine in serum using column chromatography & radioimmunoassay.

A simple method for measurement of free thyroxine (FT4) levels in serum by adsorption chromatography and subsequent radioimmunoassay (RIA) is described. Assay sensitivity observed by this method was 1.2 pg/ml. Intra-assay variability was 11.2 per cent for FT4 concentrations of 7.9 pg/ml (n = 10), while interassay variability was 23.3, 9.7 and 12.9 per cent respectively for concentrations of 2.66, 12.06 and 23.96 pg/ml (n = 16). Serum FT4 concentration estimated by this method in 79 euthyroid patients was found to be 10.8 +/- 3.1 pg/ml. Values of FT4 obtained in hypothyroid and hyperthyroid patients were outside the normal range. FT4 values obtained by this method correlated well with the standard Liso-phase FT4 kit (r = 0.8) as well as free FT4 index (r = 0.93).

Chromatography↗
PubMed1989

Monumental masons: lead and other hazards of an old trade re-visited.

A survey of lead exposure amongst gravestone inscription writers was undertaken in 12 firms of monumental masons in London and one in the East Midlands. The mean blood lead concentration in the 25 men studied was 35 micrograms/dl, with six workers exceeding 40 micrograms/dl. The four highest levels were 49, 57, 78 and 89 micrograms/dl respectively, indicating that substantial occupational exposure to lead was occurring. The men were unaware of the risks of lead exposure and the importance of not smoking or eating in their workshops. The stonemasons understood the hazards of granite stone dust, but an unexpected and common finding was an unacceptably high exposure to marble dust.

Dust↗
PubMed1989

Etiology of childhood hypothyroidism.

This study prospective without any selection bias included 80 of the 152 hypothyroid infants and children seen over the past six years. The clinical diagnosis was confirmed by TSH and thyroid hormone (T3, T4) studies. Scanning for thyroid with TC99m pertechnetate was carried out in all except seven older children with grade II and III goiters where 131I uptake studies were done. Serum thyroglobulin (RIA) was estimated and antithyroglobulin and antimicrosomal antibodies were tested. Based on thyroid 131I scan or 131I uptake, 52.5% had no demonstrable thyroid tissue except one with hypoplasia (Group I, n = 42), 25% had ectopic thyroid (Group II, n = 20), and 22.5% had normal or enlarged thyroid gland (Group III, n = 18). One hypothyroid patient of Group III had thyroiditis with high antibody titre and one was proved to have iodine deficiency). The mean age at time of diagnosis was lowest in Group I (age in months--30.3 +/- 36.2; 60.6 +/- 53.9; 106.2 +/- 69.3 in Groups I, II and III respectively. The intergroup differences in age were significant. The mean serum Tg levels increased progressively from Groups I to III. In the present series thyroid dysgenesis led to hypothyroidism in 77.5%, with athyreosis in 52.5% and ectopia in 25%. Dyshormonogenesis was noted in 20% and thyroiditis in 1.5%.

Adolescent↗
PubMed1988

Biological monitoring of occupational exposure in the chromate pigment production industry.

A survey of occupational exposure to hexavalent chromium in chromate pigment production was undertaken in factories producing lead chromate (PbCrO4) and strontium chromate (SrCrO4). Sampling pre and post-shift in a factory where SrCrO4 production had just started showed the optimum strategy for biological monitoring is the measurement of urinary chromium, in urine samples taken at the end of Friday shift and pre-shift the following Monday. However, short-term uptake may be assessed under these circumstances by the increase in urinary chromium over a shift. Body burden, representing long-term chromate exposure is best assessed by measuring chromium in whole blood or pre-shift urinary chromium at the beginning of the working week. Exceptionally high levels of chromium in blood (387-4160 nmol l-1) and urine (41-1250 nmol nmol-1 creatinine) as well as skin and nasal lesions, were discovered amongst the workforce at the strontium chromate plant. These contrasted with occupationally unexposed levels of less than 20 nmol l-1 and less than 1 nmol nmol-1 creatinine, respectively, and led to the continuation of the biological monitoring programme. At the same time, improved working practices and respiratory protection equipment were introduced. A steady elimination of chromium from whole blood with a half-life of approximately 24 days was found. This elimination rate was confirmed over a 14 day period when the workforce were completely removed from exposure. The study confirms the usefulness of biological monitoring in assessing the uptake of hexavalent chromium and control of exposure.

Chromates↗
PubMed1988

Interactions of m-xylene and aspirin metabolism in man.

In a series of experiments to investigate interactions between industrial solvents and common medications the interaction between m-xylene and aspirin was studied. As both these substances are metabolised and excreted as glycine conjugates there would possibly be competition for this conjugation pathway. Five male volunteers were exposed on separate occasions to m-xylene by inhalation (100 ppm), aspirin (1500 mg) by mouth, and m-xylene and aspirin together under controlled conditions in an exposure chamber. Urine and blood samples were collected and analysed for m-xylene, aspirin, and their metabolites. The amounts of the major glycine conjugates produced from m-xylene (m-methylhippuric acid) and aspirin (salicyluric acid) were significantly reduced by about 50% when m-xylene and aspirin were coadministered. There appears to be a mutual inhibition on the formation of the respective glycine conjugates. It is suggested that the inhibition is due to competition for either the enzymes, acyl-CoA synthetase, or glycine N-acylase. These findings have implications in the biological monitoring of workers exposed to m-xylene.

Adult↗
PubMed1987

Behavioral changes during exposure to 1,1,1-trichloroethane: time-course and relationship to blood solvent levels.

We report the results of an exposure chamber study in which volunteers were exposed to 0, 950 mg.m-3 (175 ppm) and 1,990 mg.m-3 (350 ppm) of 1,1,1-trichloroethane for 3.5 hours. The time-course of the behavioral changes and the relationship to blood concentrations of 1,1,1-trichloroethane were investigated. A pattern of performance deficits consistent with earlier work was found for some of the tests of psychomotor performance. The time-course of these appeared to be rapid, occurring in some cases within 20 minutes of exposure. For those tasks shown to be sensitive to 1,1,1-trichloroethane exposure, the development of performance changes followed the time-course of blood solvent levels. Two behavioral tests not previously used in this type of work were also employed. One was concerned with the distractability of attention and concentration (the Stroop test), and the other was concerned with analysing grammatical statements (the syntactic reasoning test). Different effects were found. In the Stroop test, enhanced performance was observed following exposure; however, the syntactic reasoning test was found to be resistant to solvent effects. Measures of short-term subjective well-being were not affected by exposure. It is suggested that the observations of time-course effects in performance and their relationship to change in blood solvent levels have implications for psychological test selection and for study designs for examining field exposure.

Analysis of Variance↗
PubMed1987

A study of Mycobacterium tuberculosis antigen and antibody in cerebrospinal fluid and blood in tuberculous meningitis.

Radioimmunoassay (RIA) techniques have been evaluated to detect specific tubercular antigen (TB Ag) and antitubercular antibody (TB Ab) in CSF and serum of patients with tuberculous meningitis (TBM). A solid-phase RIA using H37RV sonicate antigen of Mycobacterium tuberculosis, anti-BCG antibody, and staphylococcal protein A was standardized. TB Ag and TB Ab levels were noted to be significantly elevated in cerebrospinal fluid (CSF) as well in circulating immune complexes (CIC) isolated from serum samples of TBM patients as compared to control group (P less than 0.01). Detectability of disease by demonstrating elevated TB Ag and/or TB Ab levels in either CSF or CIC or both was 95%. There was no correlation between individual levels of TB Ag and TB Ab in CSF and in circulation. A follow-up study in patient over a period of 4-12 weeks revealed that TB antigen and/or TB Ab persisted in the majority of the cases for several weeks despite chemotherapy.

Antibodies, Bacterial↗