Multiprobe laser reflectometry in imaging and characterization of biological tissues.

Laser backscattered radiation from human forearm and foot were measured by multi-probe reflectometer, which consisted of one input probe and three output probes placed at distances of 2, 4 and 6 mm from the input probe. The normalized backscattered intensity (NBI) signals from the tissue surface, measured by the output probes, after digitization, were used to reconstruct the reflectance images of tissues in various layers below the skin surface. From NBI profiles measured at various locations of the tissues on the forearm the corresponding optical parameters, the scattering (mu(s)) and absorption (mu(a)) coefficients and the anisotropy parameter g, by matching these with profiles as simulated by Monte Carlo procedure were determined. From these data the optical parametric images of forearm were reconstructed which show the variation of these parameters at various locations. Similarly, the NBI data were collected from the foot sole region of healthy and diabetes subjects and their images reconstructed. These images showed the variation in the NBI in the diabetic foot sole compared to that of healthy subject, indicating the tissue structural changes. These procedures could be useful for diagnostic and therapeutic applications of lasers.

Pacemaker endocarditis caused by Pseudomonas aeruginosa treated successfully.

Infective endocarditis (IE) is a rare but serious complication of permanent cardiac pacemaker placement. Endocarditis in the presence of prosthetic valves and pacemakers is usually due to staphylococci. We present a case of pacemaker endocarditis caused by Pseudomonas aeruginosa that was successfully treated with a combination of antimicrobial therapy and percutaneous removal of the colonized lead.

An indigenously developed method for sweat collection and estimation of chloride for diagnosis of cystic fibrosis.

An indigenously developed method for sweat collection and titration method for estimation of chloride was validated. The mean difference in estimated chloride value from the known strength of saline in 50 samples was -1.04 +/- 4.13 mEq/L (95% CI: -0.07 to 2.28). The mean difference in the estimated chloride values between two observers when the test was performed on known strengths of saline solution was -2.5 +/- 4.24 mEq/L (95% CI: -3.67 to 1.33). The inter observer variability between two observers when the test was performed on sweat samples obtained from 50 individuals was -1.12 +/- 4.34 mEq/L (95% CI: -2.23 to 0.8 ). Sweat weight of more than 100 mg could be collected in first attempt in 602 of 757 (80%) patient with an average sweat weight of 230 mg. This inexpensive method of sweat collection and chloride estimation has acceptable accuracy and repeatability and can be used in resource poor setting for making a diagnosis of cystic fibrosis.

Monte Carlo simulation of photon scattering in biological tissue models.

Monte Carlo simulation of photon scattering, with and without abnormal tissue placed at various locations in the rectangular, semi-circular and semi-elliptical tissue models, has been carried out. The absorption coefficient of the tissue considered as abnormal is high and its scattering coefficient low compared to that of the control tissue. The placement of the abnormality at various locations within the models affects the transmission and surface emission of photons at various locations. The scattered photons originating from deeper layers make the maximum contribution at farther distances from the beam entry point. The contribution of various layers to photon scattering provides valuable data on variability of internal composition. Introduction.

Clinical profile of AIDS in India: a review of 61 cases.

Among 61 patients with AIDS seen in our hospital from February 1986 to June 1992, 38 (62%) had significant weight loss, 34 (56%) had fever of more than a month and 19 (31%) had chronic diarrhoea; 43 (70%) patients had at least one of the above symptoms. Tuberculosis diagnosed in 32 (52%) patients was the commonest secondary infection: 10 had only pulmonary, 15 had pulmonary and extrapulmonary and 7 only extrapulmonary tuberculosis. Secondary infections commonly found in the general population, predominantly with pathogenic bacteria were found in 27 (44%) patients, 45 (74%) patients had opportunistic infections such as oropharyngeal candidiasis 25 (41%) cryptococcal meningitis 4 (7%), recurrent zoster 1 (1.6%). Two (3.3%) patients had interstitial pneumonitis of unknown aetiology. One (1.6%) patient each had oral hairy leukoplakia or immunoblastic lymphoma. Kaposi's sarcoma was not seen in any patient. At the time of writing this, 33 (54%) patients have died; the mean duration from diagnosis of AIDS to death was 4.5 months.