Cloning, characterisation and bacterial expression of full length cDNA for the mouse liver microsomal glutathione S-transferase

We have isolated a cDNA encoding full length microsomal glutathione S-transferase (MGST) from mouse liver. The cDNA was isolated by RT-PCR using primers designed from published cDNA sequence of rat MGST with the addition of 5' Nde-1 and 3' HindIII sites, and cloned into bacterial expression vector pSP19T7LT. Deduced amino acid sequence (155 amino acids, calculated mol.mass 17512 Dalton) confirmed the identity of microsomal GST from mouse liver which has sequence homology with that of rat and human liver MGST1. Recombinant GST cDNA (Genbank accession # 159050) was expressed in BL21(DE3) in the presence of 1 mM IPTG at 30 degrees C. The expressed GST protein was found to be localised in the bacterial membrane as determined by measuring catalytic activity using CDNB and cumene hydroperoxide substrates, SDS-PAGE and Western blot analysis. We have demonstrated the cloning and expression of full length cDNA for MGST from mouse liver and have characterised the functionally active product as MGST protein. These results should facilitate studies on the role of MGST in the regulation of chemical carcinogenesis and in the prevention of oxidative stress caused by endogenous and exogenous chemicals.     

Natural radioactivity in the soil samples of Coastal Karnataka of South India

Studies on radiation level and radionuclide distribution in the region of Coastal Karnataka, India, were undertaken. The purpose of this study is to provide baseline data on radiation level and radionuclide distribution in the region for the future assessment of the impact of the nuclear and thermal power stations that are being set up in the region. Further, this study may reveal information on the transportation of radionuclides in the environment. The external gamma dose rates in air have been measured throughout Coastal Karnataka using a sensitive plastic scintillometer. The measured dose rates include both terrestrial and cosmic ray components. The gamma dose rates in air range from 26 to 174 nGy h(-1) with a median value of 74 nGy h(-1). The activities of naturally occurring radionuclides in the soil samples of the region were measured using HPGe gamma ray spectrometry, and the resulting doses in air were calculated. The activity of 40K varies from 61.0 to 316.7 Bq kg(-1) with a median of 117.5 Bq kg(-1); the activity of 226Ra varies from 20.1 to 62.3 Bq kg(-1) with a median value 35.0 Bq kg(-1) and that of 232Th from 14.3 to 48.6 Bq kg(-1) with a median value of 29.8 Bq kg(-1). The mean absorbed dose rate in air due to naturally occurring radionuclides is found to be 41.5 nGy h(-1). In addition to this, the correlations between 226Ra and 40K, 232Th and 40K, and 226Ra and 232Th were computed from the results of the concentration of these naturally occurring radionuclides. A weak correlation was observed between 226Ra and 40K and between 232Th and 40K while a moderately good correlation was observed between 226Ra and 232Th. The results of these systematic investigations are presented and discussed in this paper.     

Competitive and noncompetitive inhibition of myocardial cytochrome C oxidase in sepsis

Sepsis is the most common cause of death in intensive care units worldwide. The basic pathophysiologic defect in sepsis, causing functional abnormalities in many organ systems, remains elusive. One potential cause is disruption of oxidative phosphorylation in mitochondria. Here, we report that oxidation of cytochrome c by myocardial cytochrome c oxidase, the terminal oxidase in the electron transport chain, is competitively inhibited early in experimental sepsis (cecal ligation with single or double 23-gauge puncture) in mice. In severe sepsis (cecal ligation and double puncture, 75% mortality at 48 h), inhibition becomes noncompetitive by 48 h. The development of noncompetitive inhibition is associated with a decrease in heme a,a3 content, which is the key active site in the functional subunit (I) and catalyzes the reduction of molecular oxygen. In addition, there are persistently decreased steady-state levels of subunit I mRNA and protein after cecal ligation and double puncture. Both loss of heme and loss of subunit I could explain the observed irreversible inhibition of cytochrome c oxidase. Noncompetitive inhibition of cytochrome c oxidase may interrupt oxidative phosphorylation, leading to sepsis-associated cardiac depression. Importantly, this abnormality may underlie sepsis-associated dysfunction in other organ systems.     

Isolated extraosseous epidural myeloma presenting with thoracic compressive myelopathy

Background contextMultiple myeloma is the commonest primary malignancy of the spine, but it rarely presents as an extraosseous epidural tumor with only five cases reported in literature so far.PurposeThe purpose of this study was to heighten awareness and treatment options of a rare case of extraosseous epidural myeloma.Study designThe study design comprises a case report and literature review.MethodsWe present a 60-year-old lady with progressive paraplegia (American Spinal Injury Association grade C) with sensory blunting below T8 level of 2 months’ duration. Magnetic resonance imaging showed an extradural tumor in the dorsal epidural space from T6 to T7 without local bony involvement. She underwent a T6 and T7 laminectomy, T5–T8 pedicle screw instrumentation, and gross total resection of tumor. Histopathological diagnosis was consistent with myeloma. After surgery, the patient underwent local irradiation and adjuvant chemotherapy.ResultsNeurological improvement of one grade (American Spinal Injury Association grade C to D) was observed at 3 weeks postoperatively.ConclusionsIsolated extraosseous epidural myeloma without destruction or collapse of vertebral bodies should be included in the differential diagnosis of epidural mass lesions causing spinal cord compression. The overall prognosis in terms of survival is poor, but early decompression can prevent neurological deterioration and improve quality of life.     

The mendosal suture of the occipital bone: occurrence in Indian population,embryology and clinical significance

The Occipital occipital bone is ontogenetically and functionally unique when compared to the other bones of the skull in humans and other mammalian cousins. The Occipital occipital bone develops from six ossification centers; any defect in the ossification process will give rise to mendosal suture (accessory suture) and conditions like posterior plagiocephaly. There is a paucity of literature regarding the mendosal suture and further more, its report in Indian population is not known. The present study was conducted to find out the occurrence of mendosal suture in the Indian dry skulls. Fifteen specimens (3%) were found to have these sutures out of five hundred500 skulls examined. Nine (3.1%) samples are of male skulls out of two hundred ninety (290) and six (2.85%) samples are that of female skulls out of two hundred ten210. The mendosal suture ran close to the superior nuchal line in all specimens and traveled medially from the lambdoidal suture. The length of the sutures ranged from 0.8 cm to 2.6 cm (1.88 cm) on the right side and 1.4 cm to 2.9 cm (1.94 cm) on the left side respectively in male skulls; and 0.7 cm to 2.8 cm (1.55 cm) on the right side and 1 cm to 2.4 cm (1.42 cm) on the left side, respectively, in female skulls. The origin of mendosal suture from the lambdoidal suture was 5.7 cm to –6.3 cm (5.98 cm) from the tip of the mastoid process on the right side and 5.6 to –6.3 cm (6 cm) on the left side, respectively, in male skulls; and 5.4 cm to –5.8 cm (5.58 cm) on the right side and 5.4 cm to –5.6 cm on the left side respectively in female skulls. The occurrence and clinical significance of the present study is discussed.