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Biomedical subjects

R Ramani

Publications and source records attributed to R Ramani.

At least 37 records · Page 2Linked to original sources
PubMed1994

Fluorescent screen video imaging for checking linac beams in dynamic stereotactic radiosurgery.

Precise beam targeting is crucial to stereotactic radiosurgery. A monitoring system is described consisting of a fluorescent screen, video camera, and computer interface. Approximately ten frames are analyzed each second, verifying the beam intensity, uniformity, position, and diameter. When mounted on the gantry, the system can indicate the dynamic isocenter position using the "ball test" technique. The fluorescent screen video indicates that the 6-MV beam used for radiosurgery at our facility is acceptably stable; moreover, the small isocenter shift versus gantry and couch angles is reasonably reproducible. At our facility, quality assurance tests with this apparatus are performed every month.

Computers↗
PubMed1994

The use of radiochromic film in treatment verification of dynamic stereotactic radiosurgery.

Standard silver-based films are usually too sensitive to be used as direct indicators of dose in dynamic radiosurgery because of optical saturation. This paper describes the use of a new radiochromic film to measure 6-MV radiosurgery doses and dose distributions in a head phantom. Dose calibration of the radiochromic film was performed in the range of 2.3-50.2 Gy using light of 632- and 530-nm wavelengths. Radiosurgery dose distributions were measured using the radiochromic film in a head phantom undergoing the same treatment as a patient, and were compared with the planned distributions. For an example case (nominal 2.0-cm-diam cone), film measurement verified the calculated dose distribution in one plane. The simple measurement technique described led to experimental uncertainties of +/- 0.1 cm for the 90% and 50% isodose lines, +/- 0.3 cm for the 20% line, and +/- 0.5 cm for the 10% line. Isocenter dose was measured with an uncertainty of +/- 3%. Refinements to the technique should allow more precise measurements. It is concluded that the radiochromic film, with some limitations, is a convenient and useful tool for dynamic radiosurgery quality assurance.

Film Dosimetry↗
PubMed1994

Fungal colonization in gastric ulcers.

Until now studies on fungal colonization of gastric ulcers were retrospective involving small series of patients. This prospective study of 50 patients with gastric ulcers (25 benign and 25 malignant) revealed colonization by Candida in 17 (34%) cases. There was no significant difference in colonization between benign and malignant ulcers. Follow up revealed no difference in healing of ulcers with or without fungal colonization.

Adult↗
PubMed1994

Bacteriological study of bronchoalveolar lavage in immunocompromised hosts.

Sixty bronchoalveolar lavage samples collected from lung cancer patients attending the Pulmonary Tuberculosis and Chest Diseases Unit of the Kasturba Medical College Hospital, Manipal; were cultured for both the aerobic and anaerobic organisms. Fifty nine samples yielded bacteria in pure culture. Pseudomonas aeruginosa (34.8%) was the commonest aerobe, Peptostreptococcus was the commonest anaerobe (45.2%) isolated. Bacteroides fragilis was isolated in (23.8%) of cases. Gentamycin was found to be effective against aerobes, Metronidazole and Rifampicin against anaerobes.

Bacteria, Aerobic↗
PubMed1994

Invasive maxillary aspergillosis in an otherwise healthy individual.

Invasive aspergillosis is usually seen in immunocompromised individuals. We report the case of a 56-year-old immunocompetent housewife with Aspergillus niger invading the ethmoid and sphenoid sinuses and extending to the anterior cranial fossa. A. niger grew on three occasions (from the biopsy, mass and dura mater). In spite of medial maxillectomy and ethmoidectomy followed by craniofacial resection and antifungal drugs (amphotericin B) the patient died on tenth post-operative day.

Aspergillosis↗
PubMed1993

Molds in onychomycosis.

BACKGROUND: Onychomycosis is a major cause of nail dystrophy. The causative organisms in onychomycosis are dermatophytes, Candida and molds. A variety of molds have been isolated from nails. METHODS: Nail scrapings and clippings were collected from 100 cases and inoculated on slants containing SDA with cycloheximide 0.5 mg/mL, chloramphenicol 0.05 mg/mL, and SDA with chloramphenicol 0.05 mg/mL. RESULTS: The culture positivity rate for molds was 22%. The predominant mold isolates were Aspergillus species (86.4%, Fusarium oxysporum (4.5%), Curvularia species (4.5%) and Penicillium species (4.5%). CONCLUSION: Primary invasion of nails by molds can cause onychomycosis.

Female↗
PubMed1993

Ultrasound-guided needle aspiration of amoebic liver abscess.

This prospective study was carried out on 200 patients with clinically, ultrasonographically and serologically confirmed amoebic liver abscess. The role of ultrasound-guided needle aspiration in addition to medications was evaluated compared to drug treatment alone. Both the groups were monitored clinically and sonographically for up to 6 months after diagnosis. The initial response (after 15 days) was better in the aspirated group (P < 0.05) but resolution of abscess after 6 months were similar. There was a more rapid clinical response in the aspirated group, particularly in those with larger (> 6 cm) abscesses and there were no complications. Percutaneous ultrasound-guided needle aspiration is a safe diagnostic and therapeutic approach which enhances clinical recovery, accelerates resolution, especially in large abscesses, and prevents complications.

Biopsy, Needle↗
PubMed1993

Bacteriology of bile in obstructive jaundice.

Bile from 25 patients with obstructive jaundice was cultured for both aerobic and anaerobic organisms. Twenty one samples were positive for culture. Mixed bacterial growth was seen in 5 (20%) of the bile samples 25 aerobes and one anaerobic were isolated. Escherichia coli was the commonest aerobic isolate and Bacteroides fragilis was the single anaerobe isolated. Majority of the aerobes isolated were sensitive to gentamycin.

Bacteria, Aerobic↗
PubMed1992

Generalized lymphangiomatosis and chylothorax in the pediatric age group.

Four patients with generalized lymphangiomatosis presenting with chylothoraces are described. All four had bone involvement, two had involvement of the spleen, and one of the pericardium. The diagnosis was confirmed by typical radiology, histology, and in three patients by immunohistochemistry. Treatment was mainly palliative. Three patients died within 1/2 to three years of presentation.

Bone Diseases↗
PubMed1992

A dose-response study of the influence of propofol on cerebral blood flow, metabolism and the electroencephalogram in the rabbit.

This experiment was designed to study the effect of progressively increasing blood propofol concentrations on cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2), and the electroencephalogram (EEG). Nine New Zealand White rabbits were anesthetized with morphine (10 mg kg bolus and 2 mg/kg/h infusion) and 70% N2O. Both normothermia and normocarbia were maintained throughout the study. A 300 mum diameter platinum electrode and a 20 gauge sampling needle were inserted into the confluence of venous sinuses to permit the measurement of forebrain CBF and CMRO2. Cerebral blood flow was determined using the H2 clearance method and CMRO2 was calculated as CBF x arteriovenous O2 content difference. A single bifrontal EEG signal was also recorded. After baseline data were collected, a propofol infusion was begun, and the dose increased in a stepwise fashion from 0.28 to 1.11 mg/kg/min over 90 min (total dose 62.6 mg/kg). Every 22.5 min CBF, CMRO2, and EEG were recorded and arterial blood was sampled for the determination of propofol concentrations (by high-performance liquid chromatography). Angiotensin II was used to maintain mean arterial pressure >/=80 mm Hg. Eight animals completed the protocol. Blood propofol concentrations rose progressively in all animals, reaching a mean of 34 +/- 12 microg/ml (+/-SD) at the end of 90 min. Electroencephalogram changes during the early stages of the infusion were extremely variable. However, concentrations above approximately 20 microg/ml were associated with progressive EEG suppression, and isoelectricity developed in two animals, at blood concentrations of 41 and 52 microg/ml. There was a progressive dose-related decrease in CBF, which reached a value of approximately 62% of baseline at a concentration of 40 microg/ml (as predicted by a polynomial curve fitted to a plot of CBF versus blood concentration). The CMRO2 also decreased progressively, reaching approximately 57% of baseline at 40 microg/ml. A plot of CMRO2 versus EEG total power suggests that isoelectricity should be associated with a CMRO2 approximately equal to 53% of baseline. We conclude that propofol produces a dose-related decrease in CBF and CMRO2. The relationship between EEG suppression and CMRO2 is qualitatively similar to that seen with barbiturates.

Journal Article↗
PubMed1991

Reversible focal ischemia in the rat: effects of halothane, isoflurane, and methohexital anesthesia.

Barbiturates and the volatile anesthetic isoflurane reduce CMR to similar values. If the mechanism of barbiturate protection against focal ischemic injury is due to a reduction in cellular energy requirements, then isoflurane should similarly reduce ischemic injury. To evaluate this, spontaneously hypertensive rats underwent 2 h of reversible middle cerebral artery occlusion (MCAO) while receiving deep methohexital, isoflurane, or halothane anesthesia. Ninety-six hours postischemia, neurologic deficits were present but without a difference between groups. Mean +/- SD infarct volume, as assessed by triphenyl tetrazolium chloride staining and computerized planimetry, was significantly less in the methohexital group (n = 8; 166 +/- 74 mm3) than in either the halothane (n = 9; 249 +/- 71 mm3; p less than 0.04) or the isoflurane (n = 9; 243 +/- 62 mm3; p less than 0.03) groups. One possible explanation for the lack of protective effect for isoflurane might be related to its vasodilative properties, which could result in a cerebral vascular steal. To examine this possibility, rats anesthetized with methohexital or isoflurane underwent autoradiographic determination of CBF with or without MCAO. In isoflurane-anesthetized sham rats (n = 5; no ischemia), CBF was approximately three times greater than in methohexital-treated (n = 5) sham rats. During ischemia, although a regional reduction in flow was noted in both anesthetic groups, mean flow remained greater in the isoflurane group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The influence of a cryogenic brain injury on the cerebrovascular response to isoflurane in the rabbit.

To determine if an acute neurologic injury alters the cerebrovascular response to isoflurane, rabbits were anesthetized with morphine/N2O, mechanically ventilated, surgically instrumented, and assigned to one of three groups. Group 1 animals (n = 8) served as controls and received no injury. In Groups 2 (n = 9) and 3 (n = 8), a 30-s cryogenic injury was produced in the left parietal region using liquid N2 poured into a funnel affixed to the surface of the skull. Regional CBF was measured using microspheres. In Groups 2 and 3, flow was determined before and then 30 and 90 min after injury or at equivalent times in Group 1. After the 90-min data were collected, 1% [approximately 0.5 minimal alveolar concentration (MAC)] and then 2% (approximately 1.0 MAC) isoflurane was administered to uninjured rabbits in Groups 1 and to lesioned rabbits in Group 3. A mean arterial pressure of greater than or equal to 80 mm Hg was maintained during isoflurane administration by an infusion of angiotensin II. In uninjured rabbits (Group 1), 2% isoflurane produced bilaterally symmetrical increases in hemispheric CBF, from 76 +/- 21 (mean +/- SD) to 150 +/- 48 ml 100 g-1 min-1. CBF in the hindbrain increased from 91 +/- 25 to 248 +/- 102 ml 100 g-1 min-1. By contrast, in the lesioned rabbits of Group 3, 2% isoflurane resulted in CBF in the lesioned hemisphere changing from 56 to only 77 ml 100 g-1 min-1 (NS), while in the contralateral hemisphere, CBF rose from 68 to 97 ml 100 g-1 min-1 (also NS). These results indicate that a cryogenic injury attenuates the normal CBF response to a volatile anesthetic, both in the damaged hemisphere as well as in apparently uninjured regions distant from the injury focus. In a separate group of animals, a similar cryogenic injury abolished the CBF response to changing PaCO2 in the injured hemisphere, but not in either the contralateral hemisphere or the cerebellum. It is possible that the CBF effects of isoflurane may be mediated via some intermediary neurogenic and/or biochemical process.

Angiotensin II↗
PubMed1991

Bacteriology of diabetic foot ulcers.

Seventy five diabetic foot ulcers were cultured using optimal aerobic and anaerobic microbiologic techniques. There were a total of 223 isolates (162 aerobes and 61 anaerobes) representing an average of 2.97 bacterial species per specimen. Mixed organisms were the most common isolates. Staphylococcus aureus was the commonest isolate being recovered in 60% of cases. Anaerobic organisms were isolated in 46 patients (61.33%) and the most frequent anaerobe isolated was Bacteroides fragilis. The other organisms predominantly isolated were Proteus, Klebsiella, Pseudomonas, Peptoccus and Clostridia. Antibiogram showed discouraging pattern with commonly used antibiotics. Metronidazole and gentamicin were the most effective antimicrobial agents against anaerobic and aerobic organisms respectively. Appreciation of the causative organisms in diabetic foot and their antibiotic sensitivity is essential for institution of appropriate antibiotic therapy.

Adult↗