Use of laser to extract unwanted pacemaker leads

Of the total number of pacemakers implanted each year, 6% must eventually be replaced because of infection, lead failure, or other problems. Often however, removal of the pacing leads is precluded by scarring at the tip of the leads. Because abandoned leads can cause serious problems, we initiated the present study to test the feasibility of using a laser to remove such leads. After performing in vitro experiments to establish the laser settings required for severing leads, we implanted 6 leads, from 4 different manufacturers, in 3 dogs. Five weeks later, we passed a laser fiber through each lead to the tip and delivered a 10-watt impulse for 2 seconds, which resulted in the successful removal of all the leads. When the dogs were killed 3 days later, postmortem examination revealed no thromboembolism in the heart or lungs and no myocardial damage. Subsequent experiments in 3 human cadaver hearts-involving leads implanted for 5 years, 2 years, and 2 months-yielded the same satisfactory results as did the canine experiments.     

Tumor thickness and prognosis in clinical stage I malignant melanoma

The current grouping of patients with malignant melanoma into thin, intermediate, and thick melanomas provides a convenient but arbitrary classification which, although providing "average" survival values for each group, offers crude prognostication for the individual patient. A review of 371 patients with clinical Stage I malignant melanoma, treated during the period 1970 to 1985, was conducted. The estimated 5-year survival rate for female patients with melanomas 1.0 mm thick was 94%; for each 1-mm increment in thickness the survival rate declined by about 3%, up to the 6 mm mark, the survival rate declining thereafter by about 8% for each additional millimeter in the range of 7 to 15 mm of thickness. The estimated 5-year survival rate for male patients with melanomas 1.0 mm thick was 80%; for each 1-mm increment the survival rate declined by about 9%, up to the 10 mm mark. The proposed method of estimating the expected survival according to the patient's sex and the thickness of the primary lesion hopefully provides a more accurate and convenient method of prognostication for the clinician dealing with specific patients with intermediate or thick melanomas.     

Molecular epidemiology of norovirus variants detected in children under five years of age in Hyderabad,India

PurposeNoroviruses are common viral agents in acute diarrhea in all age groups worldwide. Norovirus has been classified into 10 genogroups, GI to GX with over 48 genotypes among them the GII.4 genotype has evolved over time with a clear pattern of periodic variant replacement. Immunity is strain or genotype specific with little or no protection conferred across genogroups. The present study was aimed to determine the epidemiology, prevalent genotypes of norovirus in children below five years of age in the Hyderabad region, India.MethodsThe stool samples and clinical data were collected from 458 children below 5 years of age comprising of cases with acute gastroenteritis (n ?= ?366) and a control group (n ?= ?92) admitted to the pediatric ward. All the samples were tested for Norovirus by ELISA and RT-PCR. Sequencing was done for predominant strains.Results10.3% (n ?= ?38) of cases and 3.2% (n ?= ?3) of the control group were found to be Norovirus positive. Predominant genotypes were GII-82.5% followed by GI-12.5%.ConclusionSequencing and Phylogenetic analyses of 20 GII.4 strains was done. All of the isolates are clustered away from published the GII.4 variants thus suggesting the appearance of a new variant.     

Outbreak of Pichia anomala infection in the pediatric service of a tertiary-care center in Northern India

An outbreak of nosocomial fungemia due to the unusual yeast, Pichia anomala occurred in the pediatric wards of our hospital over a period of 23 months (April 1996 to February 1998). A total of 379 neonates and children (4.2% admissions) were infected. The probable index case was admitted to the pediatric emergency ward, with subsequent transmission to the premature nursery, pediatric intensive care units, and other children wards. Carriage on the hands of health care personnel was likely to be responsible for dissemination of the fungus. The outbreak could only be controlled after a health education campaign to improve hand-washing practices was instituted and after nystatin-fluconazole prophylaxis to all premature neonates and high-risk infants was introduced. In a case-control study, we identified a lower gestational age, a very low birth weight (<1,500 g), and a longer duration of hospital stay as significant risk factors associated with P. anomala fungemia in premature neonates. We conducted a culture prevalence survey of 50 consecutive premature neonates and found that 28% were colonized with P. anomala at a skin or mucosal site on the date of delivery and that 20% of these neonates subsequently developed P. anomala fungemia. We performed multilocus enzyme electrophoresis on 40 P. anomala outbreak isolates (including patient and health care workers' hand isolates), and the results suggested that these isolates were identical. Our study highlights the importance of P. anomala as an emerging nosocomial fungal pathogen.     

Intraluminal Radiation for Esophageal Cancer: A Howard University Technique

The objective of radiotherapeutic management in esophageal cancer is to accomplish maximum tumor sterilization with minimal normal tissue damage. This sincere effort is most often countered by the differential in tumor dose response vs normal tissue tolerance. Intraluminal isotope radiation, with its inherent advantage of rapid dose falloff, spares the lungs, the spinal cord, and other vital structures, yet yields adequately high doses to esophageal tumor. Though in existence since the turn of the century, the method of intracavitary radium bougie application dropped out of favor due to technical difficulties imposed by the size of the radium source and radiation exposure to the personnel involved. The authors describe a simple “iridium 192 afterloading intraluminal technique” that eliminates technical problems and reduces radiation exposure considerably.     

Cell-mediated immune response in mice treated with steroidal contraceptives.

The splenomegaly assay (Simonsen, 1962) was standardized using different strains of rats and mice. Male Wistar rat (donor)-female Swiss mouse (host) was found to be the suitable combination that could be employed in subsequent experiments to study the potential of contraceptive steroids to alter CMIR. The index of splenomegaly appeared to increase in case of mice treated with combination oral contraceptives (Ovulen, Ovral or Enovid). The differences observed, however, neared significance only in the case of Ovral (0-05 less than P less than 0-1). Neither chlormadinone acetate nor megestrol acetate significantly altered the index of splenomegaly.     

Frequency dependence of spike timing reliability in cortical pyramidal cells and interneurons

Pyramidal cells and interneurons in rat prefrontal cortical slices exhibit subthreshold oscillations when depolarized by constant current injection. For both types of neurons, the frequencies of these oscillations for current injection just below spike threshold were 2--10 Hz. Above spike threshold, however, the subthreshold oscillations in pyramidal cells remained low, but the frequency of oscillations in interneurons increased up to 50 Hz. To explore the interaction between these intrinsic oscillations and external inputs, the reliability of spiking in these cortical neurons was studied with sinusoidal current injection over a range of frequencies above and below the intrinsic frequency. Cortical neurons produced 1:1 phase locking for a limited range of driving frequencies for fixed amplitude. For low-input amplitude, 1:1 phase locking was obtained in the 5- to 10-Hz range. For higher-input amplitudes, pyramidal cells phase-locked in the 5- to 20-Hz range, whereas interneurons phase-locked in the 5- to 50-Hz range. For the amplitudes studied here, spike time reliability was always highest during 1:1 phase-locking, between 5 and 20 Hz for pyramidal cells and between 5 and 50 Hz for interneurons. The observed differences in the intrinsic frequency preference between pyramidal cells and interneurons have implications for rhythmogenesis and information transmission between populations of cortical neurons.