Stimulation of DNA synthesis by rat plasma following in vivo treatment with three liver mitogens.

The present study was undertaken to determine the effect of two different types of liver cell proliferative stimuli, namely compensatory regeneration and direct hyperplasia on DNA synthesis of normal and preneoplastic isolated hepatocytes. Platelet-poor plasma (PPP) isolated from male Wistar rats treated with three different hepato-mitogens, lead nitrate (LN), cyproterone acetate (CPA) and ethylene dibromide (EDB), or subjected to surgical partial hepatectomy (PH), was tested for its ability to stimulate DNA synthesis in normal and preneoplastic hepatocytes in primary cultures. Induction of DNA synthesis was detected as early as 30 min after CPA, EDB and PH administration and persisted up to 5 days after the LN administration. In addition, hepatocytes isolated from preneoplastic liver nodules were also able to respond in culture to the DNA synthesis stimulus induced by these factors.     

Vector control through environmental management with special reference to India--approach prospectives

The introduction of different types of pollutants like those from industrial effluence, bye-products from petro-chemical industries, pesticidal application, wastages of nuclear power industries, etc. is viewed seriously by the society. For the control of vectors of disease the adoption of environmental management is, therefore, imperative. The physical methods like drainage of excess and waste water, making water unsuitable for vector breeding by adopting various indigenous methods in vogue, the intra and inter-sectrol coordination and community based activities are identified as the basic approaches for achieving this goal. Minimising the potentiality of vector breeding through source reduction and water management is thought to be the simplest, cheapest and most permanent method. For the society having varying types of habitation and varying degree of habitational facilities like planned housing, water supply and disposal, sanitation and organized anti-vector measures, the adoption of environmental management to exercise check over vector population is a promising proposition. The suitability of such an approach has already been demonstrated by MRC, (ICMR), Delhi and V.C.R.C., Pondicherry. The implementation of these methods is to be initiated right from Primary Health Centre and district level onwards and community is to be motivated to the extent that the various methods of environmental management for vector control are adopted in the routine way of life. In the present article these ideas have been touched upon and various methods of environmental management described in brief. In addition what other Governmental agencies are required to do in order to effectively implement environmental management methods are briefly enlisted.     

Mandibular fracture not shown by axial computed tomography: Benefit of computed reformation

A 36-year-old man was brought to the emergency department after being assaulted. A mandible series showed a nondisplaced fracture through the angle of the mandible extending through the left third molar tooth. Axial slices from a nonhelical computed tomographic (CT) examination of the head as well as a helical CT examination of the mandible failed to demonstrate the fracture. The fracture was well shown, however, on sagittal CT reformations. Although CT is generally regarded as more sensitive than plain radiography for the detection of fractures, fractures may be overlooked by CT if examination in only one plane is performed.     

A critical analysis of attenuation effects of different types of ear protective devices

The present study was undertaken to evaluate the noise attenuation characteristics of different types of Ear protective Devices which are commonly used. 20 healthy normal subjects’ open and closed hearing thresholds (with the usage of ear protective device) were recorded in an anechoic chamber and the attenuation charactaristics at 8 discrete frequencies were analysed and compared. Though the attenuation given by different types of ear protective devices are variable and not the ideal, still the present generation of devices have shown satisfactory attenuation characteristics, It is important that proper selection, fitment and usage of these devices should he carefully thought of prior to its usage.     

Serotonergic projections from the midbrain periaqueductal gray and nucleus raphe dorsalis to the nucleus parafasccicularis of the thalamus

By a double-labeling method combining the retrograde tracing of horseradish peroxidase and the immunocytochemical technique, serotonin-like immunoreactive neurons in the midbrain periaqueductal gray (PAG) and nucleus raphe dorsalis (DR) of the rat were observed to send projection fibers to the nucleus parafascicularis of the thalamus bilaterally with an ipsilateral dominance. These serotonin-containing projecting neurons were observed mainly at the middle-caudal levels of the ventrolateral subdivision of the PAG and less at the middle-rostral levels of the DR.     

军队高等医学院校课程教学质量评估的功能及意义

军队高等医学院校课程教学质量评估的意义及作用:具有判断教育活动、获取信息、反馈、激励、促进教学改革六项功能.     

Focused helical appendiceal computed tomography: Technique and interpretation

This article reviews a focused helical appendiceal computed tomographic technique and discusses an approach to appendiceal computed tomographic interpretation.     

Analysis of magnetization transfer effects on T1-weighted spin-echo scans using a simple tissue phantom simulating gadolinium-enhanced brain lesions

The purpose of this study was to analyze the effect of several magnetization transfer (MT) pulse and T1-weighted spin-echo (SE) sequence parameters on lesion-to-background contrast, using a simple tissue phantom emulating the T1 relaxation and MT properties of gadolinium-enhanced brain lesions. Eggbeaters (Nabisco Inc., East Hanover, NJ) liquid egg product was doped with gadolinium in six concentrations from .0 to 1.0 mmol and cooked. The gadolinium-doped egg phantom and normal volunteer brains were studied using an SE sequence with TE = 20 msec and high power, pulsed, off-resonance MT saturation. The effects of MT pulse frequency offset (1,000–6,000 Hz), sequence repetition time (TR = 500–1,000 msec, with MT power held constant), and slice-select flip angle (60–120 degrees) on the magnetization transfer ratio (MTR) and the simulated lesion-to-background contrast were determined at the different “Intralesion” gadolinium concentrations. The MTR and lesion-to-background contrast of all materials were greatest at narrow MT pulse frequency offsets. There was an inverse relationship between gadolinium concentration and MTR and a positive correlation between the gadolinium concentration and lesion-to-background (L/B) contrast, a weak negative correlation between slice-select flip angle and L/B, and a negative correlation between TR and L/B. The relaxation properties and MT behavior of the egg phantom are close to that expected for enhancing brain lesions, allowing a rigorous analysis of several variables affecting lesion-to-background contrast for high MT power, T1-weighted SE sequences.     

Modulation of trenimon-induced cytotoxicity by DT-diaphorase in isolated rat hepatocytes under aerobic versus hypoxic conditions.

Trenimon belongs to a class of aziridinylbenzoquinone anticancer drugs that cross the blood-brain barrier. In this study we have investigated the molecular mechanisms for trenimon-induced toxicity in aerobic versus hypoxic conditions with the use of freshly isolated rat hepatocytes. The following evidence suggests the mechanisms for trenimon detoxification involves reduction by DT-diaphorase, while the cytotoxic mechanism involves macromolecular alkylation under hypoxic conditions as well as oxidative stress under aerobic conditions. (a) Hepatocyte cytotoxicity induced by trenimon (250 microM) under aerobic conditions ensued following an initial induction of cyanide-resistant respiration and partial oxidation of glutathione to oxidized glutathione. Trenimon reduction to the hydroquinone by the hepatocytes was rapid. Inhibition of hepatocyte DT-diaphorase by dicumarol increased trenimon-induced cytotoxicity by approximately 10-fold, and markedly inhibited hydroquinone formation. Furthermore, both cyanide-resistant respiration and oxidized glutathione formation were markedly increased, resulting in depletion of oxygen in the media. Trenimon reduction to the hydroquinone then occurred. This suggests that DT-diaphorase in normal hepatocytes prevents the formation of the semiquinone that causes cytotoxic protein alkylation and oxidative stress. (b) Hepatocyte cytotoxicity induced by trenimon (350 microM) under hypoxic conditions ensued following glutathione depletion without oxidized glutathione formation. Inactivation of hepatocyte DT-diaphorase by dicumarol under hypoxic conditions increased trenimon-induced cytotoxicity by approximately 3.5-fold and increased semiquinone radical levels 2-fold without affecting its reduction rate. This suggests that the cytotoxic mechanism involves protein alkylation by semiquinone radicals formed by reductases catalyzing a one-electron reduction of trenimon.