Biomedical subjects

V Abraham

Publications and source records attributed to V Abraham.

26 records · Page 2Linked to original sources

PubMed1991

Effect of ultrasound on regional cerebral blood flow in neonatal rats.

By employing a laser-Doppler flowmeter, an investigation was performed to determine whether ultrasound causes a change in regional cerebral blood flow (rCBF). rCBF in neonatal rats (age: 2-6 days postgestation) was measured before, during, and after exposure of both cerebral hemispheres to continuous-wave ultrasound (1.0 MHz) at an intensity of 2.0 W/cm2 (SATA) for a period of 5 min. After 3 min of ultrasound treatment, there was a statistically significant augmentation in rCBF (p less than 0.05) with rCBF increasing by a factor of 2.7 +/- 0.4 (mean +/- SEM) after 5 min of ultrasound. This response was demonstrated to be a transient effect, because rCBF returned to its original value 4-6 min after termination of the ultrasound treatment.

Animals↗

PubMed1991

Reversible biochemical changes in the developing rat central nervous system following ultrasound exposure.

Rat embryos in utero at 10 days of gestation (gd) were exposed to the intensity of 2.5 W/cm2 (SATA) of 1 MHz continuous-wave ultrasound for 5 min. The right uterine horn was exteriorized, exposed to the ultrasound beam, and then reinserted into the abdominal cavity. Embryos from the unexposed left uterine horn served as controls. The cerebral hemispheres of each fetus were removed and analyzed for enzymatic activity at four different stages of development. There was an increase in the temperature at the surface of the intact uterus during the ultrasound exposure. No gross anatomical malformations were observed in the exposed embryos. There were no differences in brain weight or protein content between exposed and control fetuses. However, the ultrasound exposure caused a transient decrease in acetylcholine esterase and 2',3'-cyclic nucleotide phosphohydrolase activities of the insonated fetal brains compared to the control brains. Because of the relatively high temporal-average intensity, the relatively large volume of tissue exposed, and the minimal sound path through tissue, the biochemical changes observed in this experiment would be unlikely to occur in clinical examinations.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗

PubMed1990

Effects of ultrasound on DNA and RNA synthesis in preimplantation mouse embryos.

Ultrasound is used extensively to monitor the growth of ovarian follicles in in vitro fertilization and embryo transfer (IVF-ET) programs, as well as to follow the progress of early pregnancy. There have been scattered reports in the literature that exposure to ultrasound may have an adverse effect on reproduction in the rat (Bologne et al: CR Soc Biol 177:381-387, 1983; Demoulin et al: Ann NY Acad Sci 442:146-152, 1985), and also in humans (Demoulin et al: Ann NY Acad Sci 442: 146-152, 1985). We report here that diagnostic levels of pulsed ultrasound did not affect either the number of embryos produced, or the ability to incorporate labelled precursors into DNA and RNA, respectively. Measurements of temperature elevation of ovaries exposed to ultrasound showed that neither controls nor experimental tissue exhibited temperature elevation greater than 1 degree C.

Animals↗

PubMed1990

Biochemical changes in the developing rat central nervous system due to hyperthermia.

Rat embryos at 10 days of gestation were exposed to 43 degrees C for 8 minutes by submerging the exteriorized right uterine horn in heated saline solution and then reinserting the uterine horn into the abdominal cavity. At 15 days, the fetuses were removed, and cells from the cerebral hemispheres were dissociated and grown as primary cultures. Embryos from the left uterine horn served as controls. No morphological changes were observed between the cultures of cells from control and heat-exposed embryos at different days in culture. However, exposure of embryos to hyperthermia at 10 days significantly affected the developmental pattern of activities of acetylcholine esterase associated with cholinergic neurons and of 2',3'-cyclic nucleotide phosphohydrolase associated with oligodendrocytes and myelin membrane formation. These results suggest that hyperthermia at 10 days of gestation in the rat may lead to an impairment in the development of neurons and oligodendrocytes in the central nervous system.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗

PubMed1990

Effect of scan format on refraction artifacts.

Refraction artifacts occur when the ultrasound beam is bent from its original direction as it passes through a boundary between tissues having different sound speeds. Refraction artifacts result in both the improper positioning and the improper brightness of echoes displayed in clinical sonograms. The effect of scan format on the sonographic appearance of several refraction artifacts due to a circular object possessing a sonic speed differing from its surrounding tissue was studied using a mathematical model and computer generated images. A quantitative index of artifact prominence was developed to compare the differences between the rectilinear and the sector scan formats. Theoretically predicted results were compared with actual sonograms of a specially designed phantom. Results included the finding that the retrolenticular afterglow was more prominent in the sector scan format, and that differences were most prominent when the refracting object was close to the transducer.

Animals↗

PubMed1989

Effects of ultrasound on ovulation in the mouse.

In vitro fertilization and embryo transfer (IVF-ET) programs use ultrasound extensively for monitoring the growth of ovarian follicles and, subsequently, for confirming the presence of a fetal sac. There have been few reports of the effects of ultrasound on ovulation rates in mammals, and we report here that following exposure to continuous wave ultrasound at a spatial average intensity of 3.0 W/cm2 for five minutes, ovulation rates measured 10 days later were significantly reduced in mice. When temperature elevation of the exposed ovary was measured with a thermocouple, hyperthermia correlated with reduction in ovulation.

Animals↗

PubMed1989

Temperature elevation in the rat fetus due to ultrasound exposure.

The temperature elevation resulting from sonically generated heat in rat fetuses was measured for various intensity levels. The temperature elevation produced inside the fetus was higher than that on the outside surface. In live fetuses, a portion of the heat generated was carried off by the circulating blood. The temperature elevation curves were used to estimate the absorption coefficient of rat fetuses. Absorption coefficient values range from 0.065 to 0.086 Np/cm at 1 MHz. The present results are consistent with a theoretical model of temperature elevation in a heated sphere.

Animals↗

PubMedDate not supplied

Explanatory models and common mental disorders among patients with unexplained somatic symptoms attending a primary care facility in Tamil Nadu.

BACKGROUND: Patients with unexplained somatic symptoms are commonly seen in primary care. We assessed the explanatory models and common mental disorders in patients with unexplained somatic symptoms attending a primary care facility in a rural area of south India. METHODS: One hundred consecutive patients diagnosed to have unexplained somatic symptoms attending a primary care facility were examined. The Tamil version of the Revised Clinical Interview Schedule was used to assess common mental disorders and the Tamil version of the Short Explanatory Model Interview was used to assess their explanatory models. RESULTS: Ninety-eight patients thought that their problem was serious. Sixty-nine, 41 and 40 claimed that it affected their work, family and social lives, respectively. Forty-two of the patients believed in black magic. Forty-four patients satisfied the ICD-10 PC criteria for common mental disorders. Depression was the commonest diagnosis (63.6%). Patients with psychiatric diagnoses admitted to emotional problems (chi2 = 46.9; p < 0.001), and felt that their problems affected their family (chi2 = 38.5; p < 0.001), social life (chi2 = 28.6; p < 0.001) and work (chi2 = 34.4; p < 0.001). More patients who satisfied criteria for psychiatric diagnosis felt that their problems were moderate or very serious (chi2 = 21.5; p < 0.001) and they feared they might become disabled or die (chi2 = 12.2; p < 0.001). Psychiatric syndromes were significantly associated with belief in black magic (chi2 = 7.01; p < 0.01). These associations remained statstically significant after adjusting for age, gender, literacy and socioeconomic indices using logistic regression. CONCLUSION: The majority of patients held strong beliefs regarding the physical nature of their complaints, believed In the serious nature of the problem and feared disability or death. There is a need to elicit specific explanatory models regarding the nature of illness in patients who present with somatic symptoms without organic causes. Understanding the patient's perspectives is a prerequisite for providing the necessary treatment and to dispel fears.

Adult↗