Characterization of Plys-proximal morphogenetic genes of transposable bacteriophage Mu

Late during the bacteriophage Mu lytic cycle, Mu DNA must be matured and packaged from its dispersed integration sites in the host DNA in order to produce progeny virions. Whereas control of late gene transcription in Mu is becoming well understood, less is known about the phage morphogenetic process. To investigate the latter, we cloned and sequenced a approximately 4.3-kb region of the phage DNA beginning just upstream of the leftmost late promoter Plys. Previous mapping of amber mutations had located the lysis (lys) and proposed DNA maturation genes D and E in this region. When the DNA sequence was analyzed, seven potential open reading frames were found. DNA sequence analysis of amber mutations in genes D and E identified the sixth and seventh open reading frames as D and E, respectively. Cloning and expression of this region enabled production of cell-free protein extracts that specifically recognize the phage-encoded packaging sequence (pac), a characteristic exhibited by phage maturation enzymes. In addition, the E protein was found to share homology with the large subunit of many phage DNA maturation enzymes. These results support the hypothesis that D and E encode subunits of the Mu DNA maturation enzyme.

Phylogenetic analysis of symbiotic and free-living cyanobacterial cultures using DNA amplification fingerprinting

DNA amplification fingerprinting (DAF) of 17 cyanobacterial isolates belonging to symbiotic and free-living forms of 6 different genera was done. The dendrogram analysis of 17 cyanobacterial cultures revealed three major clusters. All Westiellopsis cultures formed the first major cluster and their nucleotide relatedness ranged between 71-93%. In the second major cluster, the symbiotic cyanobacterium Anabaena sp dominated and all Anabaena cultures showed 60-75% similarity with each other. Nostoc muscorum is related to Anabaena variabilis by 85% and formed the third major cluster. The dendrogram analysis of cyanobacterial isolates clearly revealed that free-living cyanobacterial cultures were closely related with each other and were diverse from the symbiotic forms.

Effect of oophorectomy on expression of calcium sensing receptor mRNA in rat duodenal mucosa

Calcium sensing receptor (CaR) in duodenal mucosa may be involved in active calcium absorption. Estrogen deficiency results in decreased intestinal calcium absorption. Effects of bilateral oophorectomy (OVX) have been studied on calcium homeostasis, bone mineral density (BMD) and CaR mRNA levels in duodenal mucosa at 4 weeks in adult female Sprague Dawley rats and compared with those in sham-operated and control group. There was no significant change in serum corrected calcium, inorganic phosphorous, calcidiol and intact parathyroid hormone in all the three groups. OVX rats had a significant decline in serum estrogen (E2) levels and alkaline phosphatase. They also had a significant decrease in BMD (DXA) at lumbar spine in vivo, and proximal and distal tibia in vitro while there was no significant change in serum E2 and BMD parameters in sham-operated and control rats. Northern blot analysis revealed no significant change in the CaR mRNA expression in duodenal mucosa in all three groups. The results suggests that CaR mRNA expression in duodenal mucosa is not affected by physiological circulating concentrations of estradiol in rats.

Review of carotid endarterectomy at Singapore General Hospital

AIM

To review the outcome of a consecutive series of patients undergoing carotid endarterectomy in a low volume setting.

DESIGN

Retrospective case review.

PATIENTS

During an 11-year period we performed 50 elective carotid endarterectomies on patients with symptomatic severe carotid stenosis: Ages of patients raised from 40 to 87 years (mean 68 years), 88% were Chinese, 6% Malay and 4% Indian. Twenty-eight percent had coronary artery disease, 64% hypertension, 27% diabetes mellitus, 50% hyperlipidaemia, and 52% were smokers. None of the patients had prior neck surgery or radiotherapy.

RESULTS

There were no deaths in this series of 50 cases. Ninety-eight percent of our patients came through surgery without major neurologic deficit. One patient (2%) suffered a major perioperative stroke. Minor neurologic sequelae included one patient (2%) with a mild non-disabling stroke, two patients (4%) with peri-operative TIA without significant sequelae; two patients (4%) with transient cranial nerve weakness (one vagus, one facial nerve).

CONCLUSION

The surgical outcomes in this series are comparable to that from larger series. Carotid endarterectomy can be safely done in a low volume setting.

Factors contributing to releak after surgical closure of perforated duodenal ulcer by Graham's Patch

BACKGROUND

Perforated duodenal ulcer is one of the common surgical emergencies. Releak after duodenal ulcer perforation closure is an important cause of mortality. This study was planned to analyse risk factors if any, which could predict releak following duodenal ulcer perforation closure and to ascertain the contribution of releak towards ultimate outcome.

METHODS

A prospective study was undertaken between September 1997 and August 1999 including all patients undergoing surgery for perforated duodenal ulcer. All patients (119) underwent a Graham's patch closure and were put on parenteral H2 antagonists and antibiotics postoperatively. Patients with releak were included in case group (9), and those without releak were included in control group (110). Factors considered for comparison among the two groups were age, pulse rate, systolic blood pressure at presentation, anthropometeric parameters, haemoglobin, serum total protein/albumin, total lymphocyte count and operative findings including size of perforation, evidence of chronicity of ulcer, quantity and nature of peritoneal fluid.

RESULTS

Age greater than 60 years (p-0.0470, CI-0.76-31.54), pulse rate greater than 110/minute (p-0.0217, CI-1.04-34.48), systolic blood pressure less than 90 mm Hg (p-0.0016, CI-2.04-71.9), haemoglobin level less than 10 g/dl (p-0.0009, CI-2.25-135.02), serum albumin less than 2.5 grams/dl (p-0.0145, CI-1.21-38.31), total lymphocyte count less than 1800 cells/mm-3 (p-0.0003, CI-8.9-42.2), size of perforation greater than 5 mm (p-0.0011, CI-1.09-36.13) were identified as risk factors for releak. Serum albumin, hemoglobin and size of perforation were independent risk factors for prediction of releak on multivariate analysis. The anthropometric parameters namely mean triceps skin fold thickness, mean mid arm circumference and mean body mass index were all significantly less in cases as compared to controls. Releak was found to be a significant cause of death in patients with perforated duodenal ulcer. A total of 8 patients died in both the groups. The mortality rate in the releak group was 55.6% (5 out of 9 patients) compared to 2.7% (3 out of 110 patients) in the control group [p-0.0001].

CONCLUSION

Releak was a significant factor influencing mortality rate after omental patch closure of perforated duodenal ulcer.

Water quality index and suitability assessment of urban ground water of Hisar and Panipat in Haryana

Ground water quality in two well-developed cities of Haryana, viz. Hisar and Panipat was assessed for drinking purpose based on water quality parameters like pH, EC, turbidity, TDS, alkalinity, total hardness, calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), chloride (Cl), nitrate (NO3), phosphate (PO4), sulphate (SO4) and fluoride (F) with respect to different land-use areas viz. residential, industrial, commercial and agricultural. Water quality index based on 9 parameters showed that at Panipat, underground water in all the land-use zones was fit for consumption (WQI < 50), whereas at Hisar, water in agricultural areas was good in quality, but that in other areas varied in magnitude of pollution (WQI > 50 to 100).

Is postoperative deep vein thrombosis a problem in neurosurgical patients with brain tumours in Singapore?

AIM

To prospectively establish the incidence of deep vein thrombosis (DVT) after cranial procedures in patients with brain tumour in Singapore.

METHODOLOGY

Over a period of one year from June 1995 to May 1996, 106 consecutive patients were recruited into the study. All patients undergoing surgery within the period of study were included. Each patient underwent a preoperative and postoperative (on postoperative Day 5 to Day 7) ultrasound examination of the lower limbs to establish the presence of DVT. Prophylaxis was limited to the peri-operative use of elastic stockings on hemiparetic limbs. There were 56 males and 50 females aged between 22 to 86 years (median 45 years). Ethnicity was Chinese, 92% Indian, 6% and other 2%. Ninety percent of the patients were ambulant pre- and post-operatively. No patient had a prior history of DVT. The distribution by pathologic diagnosis was brain metastases, 26% meningioma, 26% glioma, 19% pituitary adenoma, 14% acoustic neuroma, 6% and 9% miscellaneous tumours.

RESULTS

DVT was identified in 5/106 patients (4.7%), all of whom had either meningioma or glioma. All five cases occurred in supratentorial tumours. The tumour specific incidence was 7.1% for meningioma and 15% for glioma. 4/5 patients (80%) had pre-existing hemiparesis of the affected limb. No patient developed clinical pulmonary embolism.

CONCLUSION

The overall incidence of postoperative DVT in our population, using minimal prophylaxis, was not significantly different from the best results of prospective studies on North American or European patients employing a full regime of prophylaxis. The high-risk groups were similar. Prophylaxis using subcutaneous heparin should be used cautiously in high-risk patients.

Elevated serum cancer antigen 125 levels in advanced abdominal tuberculosis

A 48-yr-old female presented with a 1-yr history of pain in the hypochondrium and epigastrium. All routine investigations and computed tomography (CT) of the abdomen were done. CT findings revealed a well-defined cystic mass in the right ovary, and ascitis with features suggestive of secondaries over the omentum and peritoneal surface. The serum CA125 was 1255 U/mL (normal range 0-35 U/mL), which was indicative of ovarian malignancy. An exploratory laparotomy was performed. Histopathological examination of organs revealed the presence of granuloma. The patient was advised to undergo antitubercular treatment (ATT) and follow-up every month. After 1 mo of ATT, the CA125 level came down to 42 U/mL, which was near normal. As tuberculosis requires only a conservative management, we suggest that in cases of abdominopelvic mass with or without ascitis, high serum CA125 should always raise a suspicion of tuberculosis and a laparoscopy combined with peritoneal biopsy should be performed to confirm the diagnosis. This will prevent unnecessary laparotomies. Moreover, serum CA125 can be used to monitor the response of disease to antitubercular treatment.

Elevated serum cancer antigen 125 levels in advanced abdominal tuberculosis

A 48-yr-old female presented with a 1-yr history of pain in the hypochondrium and epigastrium. All routine investigations and computed tomography (CT) of the abdomen were done. CT findings revealed a well-defined cystic mass in the right ovary, and ascitis with features suggestive of secondaries over the omentum and peritoneal surface. The serum CA125 was 1255 U/mL (normal range 0-35 U/mL), which was indicative of ovarian malignancy. An exploratory laparotomy was performed. Histopathological examination of organs revealed the presence of granuloma. The patient was advised to undergo antitubercular treatment (ATT) and follow-up every month. After 1 mo of ATT, the CA125 level came down to 42 U/mL, which was near normal. As tuberculosis requires only a conservative management, we suggest that in cases of abdominopelvic mass with or without ascitis, high serum CA125 should always raise a suspicion of tuberculosis and a laparoscopy combined with peritoneal biopsy should be performed to confirm the diagnosis. This will prevent unnecessary laparotomies. Moreover, serum CA125 can be used to monitor the response of disease to antitubercular treatment.

Vestibular evidence for the evolution of aquatic behaviour in early cetaceans

Early cetaceans evolved from terrestrial quadrupeds to obligate swimmers, a change that is traditionally studied by functional analysis of the postcranial skeleton. Here we assess the evolution of cetacean locomotor behaviour from an independent perspective by looking at the semicircular canal system, one of the main sense organs involved in neural control of locomotion. Extant cetaceans are found to be unique in that their canal arc size, corrected for body mass, is approximately three times smaller than in other mammals. This reduces the sensitivity of the canal system, most plausibly to match the fast body rotations that characterize cetacean behaviour. Eocene fossils show that the new sensory regime, incompatible with terrestrial competence, developed quickly and early in cetacean evolution, as soon as the taxa are associated with marine environments. Dedicated agile swimming of cetaceans thus appeared to have originated as a rapid and fundamental shift in locomotion rather than as the gradual transition suggested by postcranial evidence. We hypothesize that the unparalleled modification of the semicircular canal system represented a key 'point of no return' event in early cetacean evolution, leading to full independence from life on land.

Cosmesis in neurosurgery: is the bald head necessary to avoid postoperative infection?

AIM

The aims of this study were to prospectively investigate the incidence of postoperative wound infection following elective cranial surgery, when scalp hair removal was limited to the line of the incision, and to see if there was an increased risk of infection.

MATERIALS AND METHODS

This is an observational study of 57 consecutive adult elective cases operated upon without head shave (between July 1998 and December 1998). The method of scalp preparation is described.

RESULTS

During the follow-up period, there was 1 case (1.75%) of postoperative wound infection. This was compared with retrospective data, and was not found to be statistically significant.

DISCUSSION

In a review of earlier studies and a search into the history of aseptic surgery, no scientific ground for the practice of shaving was found. We suggest that there is no advantage in shaving patients in terms of reducing wound infection rates.

A fatal case of systemic brucellosis

A 65 years man presented with fever, drenching sweats, progressive dyspnoea, backache and weight loss. On examination, he had wide pulse pressure, clubbing, retinal hemorrhages, aortic and mitral regurgitation, hepatosplenomegaly, lower spinal tenderness and bilateral basal crepitations. Transthoracic 2D-echocardiography showed a large vegetation on the aortic valve. Antibody titers for brucella were positive. X-ray spine was suggestive of brucella spondylitis. Early surgical intervention was planned and the patient was given combination antibiotic therapy. The course was complicated by renal failure and the patient succumbed while being taken up for surgery.