Paediatric Anatomical Models in Radiotherapy Applications.

Anatomical models have key applications in radiotherapy, notably to help understand the relationship between radiation dose and risk of developing side effects. This review analyses whether age-specific computational phantoms, developed from healthy subjects and paediatric cancer patient data, are adequate to model a paediatric population. The phantoms used in the study were International Commission on Radiological Protection (ICRP), 4D extended cardiac torso (XCAT) and Radiotherapy Paediatric Atlas (RT-PAL), which were also compared to literature data. Organ volume data for 19 organs was collected for all phantoms and literature. ICRP was treated as the reference for comparison, and percentage difference (P.D) for the other phantoms were calculated relative to ICRP. Overall comparisons were made for each age category (1, 5, 10, 15) and each organ. Statistical analysis was performed using Microsoft Excel (version 16.59). The smallest P.D to ICRP was for Literature (-17.4%), closely followed by XCAT (26.6%). The largest was for RT-PAL (88.1%). The rectum had the largest average P.D (1,049.2%) and the large bowel had the smallest (2.0%). The P.D was 122.6% at age 1 but this decreased to 43.5% by age 15. Linear regression analysis showed a correlation between organ volume and age to be the strongest for ICRP (R2 = 0.943) and weakest for XCAT (R2 = 0.676). The phantoms are similar enough to ICRP for potential use in modelling paediatric populations. ICRP and XCAT could be used to model a healthy population, whereas RT-PAL could be used for a population undergoing/after radiotherapy.

POST MORTEM DIAGNOSIS OF EARLY MYOCARDIAL INFARCTION.

Acute Myocardial Infarction as a cause of death is diagnosed in many cases of sudden death based on the indirect evidence of critical narrrowing (75%) of one or more coronary arteries. Microscopic evidence of infarction is seen in H & E stained sections only if the person has survived for a minimum period of 6 hours after sustaining fatal ischaemic attack. In this study we have used two laboratory methods for visualisation of infarcts of lesser 'age', viz.-Triphenyl Tetrazolium Chloride (TTC) Macro Test and Acridine Orange Fluorescence Study. The former is a gross staining procedure which can reveal infarcts of 5-6 hours age, while the later is UV Fluorescent microscopic examination capable of detecting infarcts of 2 hours age. Although these procedures are well accepted ones, the aim of this article is to induce Forensic Pathologists to incorporate these tests in the study protocol of all sudden death cases with the aim of 'visualising' the infarct rather than basing the diagnosis on indirect evidence of critical narrowing of Coronaries.

AIDS-MEDICOLEGAL ASPECTS.

AIDS/HIV Positivity has been the most widely debated disease of this century. Reasons for this are manifold, viz-the non-availability of cure and consequent 100% mortality of a full blown case; its mode of transmission-homosexual and heterosexual activities; widespread occurrence amongst 'main liners'; and patients receiving blood and blood products etc. These aspects have created a dreaded halo around AIDS as well as social stigma. Even the medical community is not exempt from these problems. Unfortunately, legislatures around the world, more so in India, have lagged behind in clarifying many legal issues involved by not enacting specific laws pertaining to AIDS. Consequently many legal & ethical doubts arise in the minds of doctors when confronted with a case of AIDS either in a live patient or in a dead body. In addition, the disease being incurable & 100% fatal, makes it essential to adopt effective preventive measures which in turn need thorough knowledge of social aspects of the epidemic. Certain medicolegal, and ethical aspects of the problem of AIDS are recapitulated in this article for the benefit of the medical community.

Superficial siderosis of the nervous system.

A male patient had been operated in 1990 at a different hospital for a suprasellar mass lesion causing progressive blindness. At exploration, the mass was felt to be inflammatory in nature with arachnoiditis and hydrocephalus. Deep yellow staining of tissues round the mass was recorded at the time of first surgery. The patient was readmitted in 1996 for progressive visual failure, ataxia, mental changes and deafness. MRI confirmed persistence of suprasellar mass and showed the characteristic findings of superficial siderosis of CNS. On reexploration, the mass had multiple vessels over the walls and contained xanthochromic fluid. It was excised and histologically examined to be an epidermoid with a cyst. The patient developed chest infection, became drowsy and died. The MRI picture, the CSF finding and the yellow staining of tissue confirmed the diagnosis of superficial siderosis of the CNS, which was first thought of after seeing the diagnostic MRI. The cause of the superficial siderosis was recurrent bleeding from the tumour.

Fast inducible repair of microinjected UV-irradiated SV40 DNA in monkey kidney cells.

In monkey kidney cells (TC-7), microinjected with UV-irradiated (103-362 J/m2) SV40 DNA, the expression of viral antigens decreases in a UV-dose-dependent manner and the viral genes are not repaired constitutively. When the viral DNA is microinjected 4 h after UV-irradiation (40 J/m2) of host cells, the expression of viral antigens is restored in all cells. The time course of restoration of viral gene expression function shows that in UV-irradiated cells the repair is induced rapidly and fully within 2 h and the induced state is maintained for 24 h. Intact viral DNA molecules, microinjected during the period of induction of cellular UV repair, are expressed less efficiently than UV-irradiated viral genomes.

Tinidazole in the treatment of trichomoniasis, giardiasis and amoebiasis. Report of a multicentre study.

An open multicentre trial was undertaken in 8 countries to assess the efficacy and tolerance of short course treatment regimens of tinidazole Trichomoniasis: of 859 patients with trichomonal vaginitis given a 2g single dose of tinidazole 717 (95.2%) were cured. Side-effects occurred in 82 patients (9.5%) and in 12 were regarded as severe. Giardiasis: of 74 children with symptomatic giardiasis given tinidazole in a single dose of approximately 50 mg/kg body weight, 65 (88%) were parasitologically and symptomatically cured. 2 (2.7%) complained of side-effects, none of which was severe. Intestinal amoebiasis: of 502 patients, comprising 458 adults and 44 children, with symptomatic intestinal amoebiasis who received tinidazole as a single daily dose on 2 to 3 consecutive days, 477 (95%) were parasitologically cured with complete or marked improvement in symptoms. Side-effects occurred in 50 patients (10%) and in 11 were regarded as severe. Amoebic liver abscess: 82 patients were given tinidazole in single doses of 2g on 3 consecutive days. The response was rated as excellent in 60 and good in 17 (overall cure 93.9%). Side-effects occurred in 9 patients (10.9) and in 2 were regarded as severe. These findings confirm the efficacy and tolerance of short regimens of tinidazole given in single daily doses.

Behaviour of the platinum electrode as a pH electrode.

The platinum wire electrode behaves as a good pH electrode in the titration of 1.0 and 0.1N sulphuric or hydrochloric acid with the equivalent concentration of sodium hydroxide. The efficiency is greater when sulphuric acid is used. The end-points obtained are very close to those obtained with a glass-calomel system.