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Biomedical subjects

I Perkash

Publications and source records attributed to I Perkash.

At least 19 recordsLinked to original sources
PubMed2001

Progressive decrease in bone density over 10 years of androgen deprivation therapy in patients with prostate cancer.

OBJECTIVES: Several reports suggest an increased incidence of osteoporosis and concomitant fractures in men receiving androgen deprivation therapy (ADT) for prostate cancer. We sought to estimate the longitudinal effects of ADT on loss of bone density in this cross-sectional study. METHODS: Hip and spine bone mineral density (BMD) studies were performed by dual-energy x-ray absorptiometry on 36 patients with prostate cancer. The year 0 cohort (n = 8) consisted of patients who had not yet begun planned ADT. These men were compared to patients receiving ADT who underwent BMD evaluation at year 2 (n = 6), year 4 (n = 7), year 6 (n = 5), year 8 (n = 5), and year 10 (n = 5) of therapy. All BMD values for the patients with prostate cancer were compared to age-matched control subjects. RESULTS: Hip BMD was significantly lower in patients on ADT (mean BMD 0.802 g/cm(2)) compared with those not on ADT (mean BMD 0.935 g/cm(2)). Patients at year 0 had hip and spine BMD similar to age-matched control subjects. There was a significant trend for decreased hip BMD with increasing years of ADT (r = 0.46, P = 0.00008). This relationship was more dramatic when hip BMD at each time point was compared to age-matched control subjects (r = 0.55, P = 0.5 x 10(-16)). This bone loss was evident even up to year 10. BMD loss was more dramatic in patients who had undergone surgical castration than those receiving medical ADT (P = 0.08). Patients on intermittent ADT had similar BMD loss as patients on continuous ADT at year 2 and year 4 but demonstrated less bone loss at year 6 (P = 0.07) despite equivalently low testosterone levels. CONCLUSIONS: There is diminished BMD with increasing duration of ADT. Continuous ADT and surgical castration may be more deleterious than medical therapy, particularly when the medical therapy is given in an intermittent fashion.

Aged↗
PubMed2001

Functional magnetic stimulation of the colon in persons with spinal cord injury.

OBJECTIVE: To evaluate the usefulness of functional magnetic stimulation (FMS) as a noninvasive method to stimulate the colon in individuals with spinal cord injury (SCI). DESIGN: A prospective before-after trial consisting of 2 protocols. SETTING: FMS laboratories of 2 SCI centers. PARTICIPANTS: Two able-bodied men and 13 men with SCI levels ranging from C3 to L1. Protocol 1 consisted of 9 subjects, 2 of whom were excluded from the analysis. Protocol 2 consisted of 4 subjects. INTERVENTION: Commercially available magnetic stimulators with round magnetic coils (MCs) were used. Protocol 1 measured the effects of FMS on rectal pressure by placing the MC on the transabdominal and lumbosacral regions. Protocol 2 consisted of a 5-week stimulation period to investigate the effects of FMS on total and segmental colonic transit times (CTTs). MAIN OUTCOME MEASURE: An increase in rectal pressure and a decrease in CTT by magnetic stimulation. RESULTS: Data were averaged and the standard error of the mean was calculated. Statistically significant changes in rectal pressure and CTT were also measured. Rectal pressures increased from 26.7 +/- 7.44cmH(2)O to 48.0 +/- 9.91cmH(2)O, p =.0037, with lumbosacral stimulation, and from 30.0 +/- 6.35cmH(2)O to 42.7 +/- 7.95cmH(2)O, p =.0015, with transabdominal stimulation. With FMS, the mean CTT decreased from 105.2 to 89.4 hours, p =.02. CONCLUSION: FMS is able to stimulate the colon and reduce CTT. FMS is a noninvasive, technological advancement for managing neurogenic bowel in patients with SCI.

Adult↗
PubMed2001

Functional magnetic stimulation for conditioning of expiratory muscles in patients with spinal cord injury.

OBJECTIVE: To evaluate the effectiveness of functional magnetic stimulation (FMS) in conditioning expiratory muscles patients with spinal cord injury (SCI). DESIGN: A prospective before-after trial. SETTING: The Functional Magnetic Stimulation Laboratory of the SCI Health Care Group, VA Long Beach Health Care System, and the Spinal Cord Injury Services, Department of Veterans Affairs, Palo Alto Health Care System. PARTICIPANTS: Eight men with tetraplegia. INTERVENTION: Expiratory muscle training was achieved by placing a magnetic stimulator with a round magnetic coil along subjects' lower thoracic spine. MAIN OUTCOME MEASURES: Measures taken were the maximal expired pressure at total lung capacity (MEP-TLC) and at functional residual capacity (MEP-FRC), expiratory reserve volume (ERV), and the forced expiratory flow rate at TLC (FEF-TLC) and at FRC (FEF-FRC) by subjects' voluntary maximal efforts. RESULTS: After 4 weeks of conditioning, the mean +/- standard error of the mean values were: MEP-TLC, 55.3 +/- 8.6cmH(2)O; MEP-FRC, 29.6 +/- 5.6cmH(2)O; ERV,.57 +/-.08L; FEF-TLC, 4.3 +/- 0.5L/s; and FEF-FRC, 1.9 +/- 0.2L/s. These values correspond to, respectively, 129%, 137%, 162%, 109%, and 127% of pre-FMS conditioning values. When FMS was discontinued for 2 weeks, the MEP-TLC returned to its pre-FMS training value. CONCLUSION: A 4-week protocol of FMS of the expiratory muscles improves voluntary expiratory muscle strength significantly, indicating that FMS can be a noninvasive therapeutic technology in respiratory muscle training for persons with tetraplegia.

Analysis of Variance↗
PubMed2001

Functional magnetic stimulation facilitates colonic transit in rats.

OBJECTIVE: To investigate the effect of functional magnetic stimulation (FMS) on colonic transit in rats. DESIGN: Experimental. SETTING: Functional magnetic stimulation laboratory in a Veterans Administration health care system. ANIMALS: Twenty-four female Wistar rats, divided into an experimental group and a control group. INTERVENTIONS: All rats had technetium 99m (Tc 99m) infused through a cecal catheter to assess colonic transit times. FMS was performed over the cervical region; a figure of 8 magnetic coil was used in the experimental group. The colon was removed and sectioned into 10 segments, and a stool sample was taken in both groups. MAIN OUTCOME MEASURES: Distribution of radioactivity within the large intestine and stool were measured. RESULTS: Geometric center calculations showed significant differences (p <.001) between the control group and the experimental group when the distribution of radioactivity along the colon was measured. The percentage of Tc 99m recovered from the stool in the experimental group was significantly higher than the percentage recovered from the control group. CONCLUSION: FMS facilitates colonic transit in a rat model.

Animals↗
PubMed2000

Functional magnetic stimulation facilitates gastrointestinal transit of liquids in rats.

The purpose of this study was to investigate the effect of a relatively novel technology, functional magnetic stimulation (FMS), on gastrointestinal transit of liquids in rats. Orogastric gavage with technetium-99 solution was used to assess gastric emptying and gastrointestinal transit time in 92 rats. FMS was performed over the anterior cervical and/or dorsal thoracolumbar regions using a figure-8 coil. Stimulation protocols were 1, 2, or 4 h in length. FMS accelerated gastric emptying and decreased gastrointestinal transit time. The acceleration was dependent on the stimulation parameters used as well as on the duration of the protocol; high levels of FMS produced a quicker effect, whereas lower levels were effective at later times. This study provides evidence that FMS could be an alternative or adjunct therapy to treat disorders in gastrointestinal motility.

Analysis of Variance↗
PubMed1999

Methicillin-resistant Staphylococcus aureus in patients with spinal cord injury.

During the past decade, methicillin-resistant Staphylococcus aureus (MRSA) has become a major cause of nosocomial and community-acquired infections in the United States. A retrospective chart review of MRSA-positive cases from January 1990 to December 1994 was done to assess the extent of the problem, the factors associated with MRSA acquisition, and the effectiveness of a Center for Disease Control (CDC) protocol to treat MRSA infection in a population with spinal cord injury (SCI). Seventy-four percent of the patients acquired MRSA during their hospitalization. Urine was the most common site of colonization, and 73 percent of the patients with positive urine cultures managed their bladders with indwelling catheters. Implementation of the CDC protocol in 1991 was associated with a decrease in the MRSA incidence rate in subsequent years. Other simple methods of treatment, such as bladder irrigation, were also effective. To control the spread of MRSA, a continual concerted effort by hospital staff through education and implementation of the MRSA protocol is necessary.

Adult↗
PubMed1999

Functional magnetic stimulation: a new modality for enhancing systemic fibrinolysis.

OBJECTIVE: To investigate whether functional magnetic stimulation (FMS) of the leg muscles could enhance systemic fibrinolysis. DESIGN: A within-subject analysis of systemic fibrinolysis before and after 60 minutes of FMS. SETTING: The Functional Magnetic Stimulation and Special Coagulation Laboratories in the Spinal Cord Injury Service at a Veterans Administration health care facility. PARTICIPANTS: Twenty healthy volunteers were recruited. The exclusion criteria were: (1) personal or family history of venous or arterial thrombosis, (2) personal or family history of cardiac arrythmias, (3) current use of medication, and (4) the presence of a cardiac pacemaker or other metallic implants. MAIN OUTCOME MEASURES: Whole blood clot lysis time (WBCLT) and tissue plasminogen activator (t-PA) antigen determined at baseline and 10 and 60 minutes after FMS. RESULTS: A significant decrease was observed in the mean WBCLT after FMS. The WBCLT decreased from 17+/-1.3 h before FMS to 12+/-1.0 h and 11+/-0.8 h at 10 and 60 minutes post-FMS, respectively. The mean t-PA antigen levels did not show a significant change (p = .6701) from pre-FMS (6.7+/-0.91 ng/mL) to 10 min post-FMS (6.8+/-0.91 ng/mL) and 60 min post-FMS (7.0+/-1.02 ng/mL). Several patterns of fibrinolytic response to FMS were observed. They differed in relation to the degree of enhancement, the period at which maximum enhancement occurred, and the corresponding t-PA antigen levels observed. CONCLUSIONS: The FMS-induced contractions of the leg muscles enhanced systemic fibrinolysis ex vivo. The improvement in fibrinolysis occurred immediately after FMS and was also observed at 60 minutes post-FMS. FMS appears to produce a sustained enhancement of systemic fibrinolysis that may prove useful in deep-vein thrombosis prophylaxis.

Adult↗
PubMed1998

Chronology and urodynamic characterization of micturition in neurohormonally induced experimental prostate growth in the rat.

The purpose of this study was to evaluate the impact of chronic urinary tract obstruction which was produced in the rat using neurohormonally induced experimental prostate growth. In this model, we considered the chronology of changes in the micturition characteristics of awake rats relative to prostate weight and stiffness. The corresponding urodynamic characteristics of both the upper and lower tracts were evaluated in anesthetized animals relative to the development and extent of the obstruction produced. Prostate growth was produced by capitalizing on the synergistic properties afforded by the combined administration of dihydrotestosterone propionate (DHT) and the alpha1 adrenoreceptor antagonist prazosin (PRZ). DHT (1.25 mg/kg/day) was dissolved in 0.1 ml sesame oil (SO) and coadministered with PRZ 30 microg/kg/day subcutaneously for 14 days to 12 experimental rats. SO alone was given to 8 control rats. Micturition studies were first performed using all 20 awake rats, which were placed unrestrained in metabolic cages. Urodynamics of the upper and lower urinary tracts were repeated following anesthesia at the 5th, 10th, and 15th weeks after initiation of hormonal or SO treatment. Following the urodynamic studies, the rats were killed and prostates were removed and weighed, and stiffness was measured. Studies with awake rats show that hormonal treatment produces a significant and progressive increase in mean frequency of micturition, ranging from 0.63+/-0.16 in controls and reaching the maximum of 2.15+/-0.40/hr by the 10th wk. Results from urodynamic studies with anesthetized rats also show typical and progressive obstructive characteristics: maximum detrusor voiding pressure (Pdetmax) increased from 52.7+/-2.03 in controls to a maximum of 77.5+/-2.2 cm H2O by the 10th week; urethral opening pressure Puo likewise increased from 52.6+/-2.7 in controls to 73.3+/-2.1 cm H2O in experimental rats. The duration of time during which the detrusor sustains contraction during voiding also rose, from 16.8+/-1.8 sec in controls to 32.0+/-3.2 sec by the 10th week. There were no significant changes in bladder capacity, baseline filling pressures, or arterial pressures. Prostate weight increased significantly from 0.76+/-0.05 g in controls to 1.17+/-0.1 g by the 15th week. Similarly, stiffness increased from control values of 1.33+/-0.18 g/cm to a maximum of 3.59+/-0.14 g/cm by the 10th week. It is concluded that neurohormonally stimulated prostate growth in the rat is a suitable animal model for the study of the development of urinary tract obstruction. Obstructive characteristics were validated in both awake rats by the increase in the frequency of micturition and urodynamically under anesthesia in terms of elevations in maximum detrusor pressures, urethral opening pressure, detrusor contraction time, and prostatic stiffness. The effect of obstruction was further shown to be associated with vesicoureteral reflux during micturition and elevated upper tract pressures.

Adrenergic alpha-Antagonists↗
PubMed1998

Effect of alpha1 adrenoceptor antagonist on the urodynamics of the upper and lower urinary tract of the male rat.

In this investigation, we examined the impact of the alpha1 adrenoceptor (alpha1-ADR) antagonist prazosin on the urodynamic characteristics of upper urinary tract function and associated micturition characteristics of the adult male rat. The focus of the study was to evaluate the extent to which prazosin affects urine production and ureteral transport relative to its effect on micturition. Control micturition studies were first performed using 28 awake Sprague-Dawley rats that were placed in metabolic cages for characterization of the frequency and mean and total volume voided over a 4-hr period. Following the control studies, the effect of intraperitoneal prazosin, 30 microg/kg, was evaluated under identical conditions. Urodynamic studies were done to identify the bladder filling and voiding characteristics of anesthetized rats that were infused with saline at a rate of 0.22 ml/min. From the urodynamic studies the parameters of bladder pressure (Pves) and volume (V) during filling, urethral opening (Puo) measured at the moment of micturition, and maximum detrusor pressure during voiding (Pdetmax) were evaluated. External sphincter electromyography was also monitored and recorded together with bladder pressure during voiding. Renal pelvic pressure was measured via a nephrostomy catheter and recordings were made simultaneously with bladder filling and voiding. The upper urinary tract was visualized using microscopic video imaging of the ureter, contrasted by perfusing the renal pelvis with indigo carmine. Characterization of upper tract transport was made in terms of renal pelvic pressure, ureteral peristaltic rate, and bolus length and velocity. The results show that in the awake rat, 30 microg/kg of prazosin decreased the urine production rate from 4.8 +/- 0.074 to 1.6 +/- 0.23 ml (P < 0.001) and micturition frequency by a similar proportion from 1.99 +/- 0.44 to 0.53 +/- 0.08/hr. In the lower urinary tract, prazosin did not change the baseline pressure of the bladder but produced significant dose-dependent decreases in Pdetmax, Puo, and frequency of micturition. In the upper urinary tract, ureteral and pelvic frequencies decreased, whereas the length of bolus increased significantly corresponding to increased doses of prazosin. These results suggest that, although prazosin facilitates micturition by reducing urethral opening pressure, it also reduces the rate of urine production and modulates the function of urine transport in the upper urinary tract.

Adrenergic alpha-Antagonists↗
PubMed1998

Limb salvage surgery in spinal cord injury patients.

Advances in the care and rehabilitation of patients with spinal cord injuries (SCI) have resulted in extended survival following injury. Increasingly, we are faced with difficult chronic lower extremity ischemic complications in SCI patients. Recognizing limitations associated with amputation in these nonambulatory patients, we report the preliminary results of a program of selective limb salvage via arterial reconstructive surgery. Retrospective chart review was performed on the records of the Veterans Affairs Palo Alto Health Care System SCI unit. Since 1989, 15 revascularization procedures were identified in 10 SCI patients. All patients suffered from ischemic ulceration and/or gangrene. Procedures performed included femorotibial bypass (8), aortofemoral bypass (4), femoro-femoral bypass (2), and axillobifemoral bypass (AXF) (1). All patients were men. The mean age was 56 (range 43-73). Follow-up was available on 10 procedures performed in seven patients since 1992. Mean follow-up was 17 months. One patient died 3 months following distal bypass. The AXF occluded within 1 month. One distal bypass occluded in the immediate postoperative period and could not be salvaged. All other grafts remain patent, and all wounds have healed following successful bypass. One patient developed pressure ulceration following AXF grafting due to postoperative upper extremity limitations. No other complications were encountered. Standard arterial reconstructive procedures can be performed safely and successfully in SCI patients, despite diminished limb blood flow due to inactivity, and atrophic arteries, muscle, and fascia. Axillobifemoral bypass grafting may not be suitable in SCI due to requirements for upper extremity-based mobility. Confirmation of benefit of limb salvage versus amputation awaits comparison between patients eligible for either procedure.

Adult↗
PubMed1998

Functional magnetic stimulation for restoring cough in patients with tetraplegia.

OBJECTIVE: To evaluate the usefulness of functional magnetic stimulation (FMS) as a noninvasive method for assisting cough in patients with tetraplegia. DESIGN: A prospective before-after trial. SETTING: The functional magnetic stimulation laboratory of a spinal cord injury (SCI) service. PARTICIPANTS: Thirteen male SCI patients, with injury levels between C4 and C7. INTERVENTION: A commercially available magnetic stimulator with a round magnetic coil (MC) was used. Expiratory muscle activation was achieved by placing the MC along the lower thoracic spine. MAIN OUTCOME MEASURE: The planned major outcome measures were the maximal expired pressure (MEP), expiratory reserve volume (ERV), and forced expiratory flow rate (FEF) by FMS compared with voluntary maximal efforts. Another outcome was the optimal MC placement and stimulation intensity that would result in highest expired pressure. RESULTS: The mean (+/-SEM) MEP, ERV, and FEF generated by FMS were 66.40 +/- 6.69 cmH2O, .77 +/- .14 L, and 5.28 +/- .42 L/sec, respectively. They were 118%, 169%, and 110% of voluntary maximum efforts. MC placement at the T10 to T11 spinous process and stimulation intensity at 80% produced the highest MEP and FEF. CONCLUSION: FMS of the expiratory muscles produced significant expired pressures, volumes, and flow rates when compared with voluntary maximum efforts; therefore, FMS can be used as an effective method to restore cough in tetraplegic patients.

Abdominal Muscles↗
PubMed1998

Use of contact laser crystal tip firing Nd:YAG to relieve urinary outflow obstruction in male neurogenic bladder patients.

BACKGROUND AND OBJECTIVE: Endoscopic urologic procedures for transurethral prostatectomy (TURP), external sphincterotomy (TURS), bladder neck incision, and incising strictures using diathermy have resulted in excessive bleeding and risk of hyponatremia. This presentation is a review of a methodology developed to evaluate the use of contact laser crystal firing Nd:YAG laser. Details of the technique are presented. RESULTS: A review of 129 patients following laser TURS with 34% of these patients also needing TURP and 29% of patients also requiring TUIP has been done. Following contact laser endoscopic surgery, the catheter was removed in 24 hours. There was minimal to nil haemorrhage perioperatively and secondary haemorrhage was absent. CONCLUSIONS: The technique employing contact laser crystal provides an easy TURP, TURS, and stricture ablation. Follow up indicates durable results.

Equipment Design↗
PubMed1998

Surgical challenge of massive bilateral staghorn renal calculi in a spinal cord injury patient.

We report a rare case of massive bilateral staghorn calculi in a spinal cord injury patient with significant renal compromise. The patient was successfully treated with percutaneous nephrolithotomy to achieve a stone-free status. The various options of treatment are discussed with special attention to the technical aspects necessary to achieve complete eradication of the stone burden during percutaneous nephrolithotomy. Furthermore, the importance of treating bladder dysfunction and urinary metabolic abnormalities is emphasized.

Follow-Up Studies↗
PubMed1997

Micturition by functional magnetic stimulation in dogs: a preliminary report.

The effectiveness of functional magnetic stimulation (FMS) technology on bladder contraction and bladder emptying was evaluated in ten normal neurologically intact male dogs. In seven animals, FMS of the bladder was performed by using a commercially available magnetic coil (non-water-cooled) for stimulating the sacral nerves or over the suprapubic region. With sacral stimulation, the mean change in bladder pressure (Pves) was 68.0 +/- 12.96 cm H2O; with suprapubic stimulation, the mean change in Pves was 40.7 +/- 8.08 cm H2O. This change in Pves by sacral stimulation was higher than suprapubic stimulation (P < 0.01). In three additional animals, voiding was demonstrated by using a specialized water-cooled magnetic coil and by stimulating the sacral nerves with an intermittent stimulation sequence. Voiding occurred in all three animals and was reproducible. In summary, FMS of the bladder has the potential to be a useful non-invasive technology for bladder emptying and bladder training in patients with neurogenic bladder.

Animals↗