PubMed Health⌕ Search

Biomedical subjects

R W Lewis

Publications and source records attributed to R W Lewis.

At least 19 recordsLinked to original sources
PubMed1992

Methylene chloride--an inhalation study to investigate pathological and biochemical events occurring in the lungs of mice over an exposure period of 90 days.

Male B6C3F1 mice were exposed to 4000 ppm methylene chloride (MC) for 6 hr/day, 5 days/week for up to 13 weeks. Groups of mice were killed at intervals from Day 2 to Week 13. Whole lungs were examined morphologically, immunocytochemically, and biochemically. Biochemical and morphological examination was also performed on isolated Clara cells. The major initial morphological effect seen in lungs was acute Clara cell damage after one exposure to MC. However, this damage appeared to resolve after five consecutive daily exposures to MC. After a 2-day interval the Clara cell lesion reappeared on subsequent reexposure to MC. However, the severity of the lesion decreased over the duration of the study. The appearance and disappearance of the lesion in the Clara cell correlated well with the activity of cytochrome P450 monooxygenase in the Clara cell as assessed immunocytochemically (cytochromes P450IIB 1 and 2) in the whole lung and biochemically in the freshly isolated Clara cell (determined by ethoxycoumarin O-dealkylation and aldrin epoxidation). When there was a marked decrease in cytochrome P450 monooxygenase activity the lesion was not present. This suggested that with time the lung (Clara cell) has developed tolerance to MC possibly due to the inactivation of a cytochrome P450 isozyme. The glutathione S-transferase metabolism of MC by the lung cytosol remained virtually unaltered throughout the study. Events accompanying the discussed changes include (1) a significant increase in nonprotein sulfhydryl in the lungs of all exposed animals, (2) altered plating characteristics of the isolated Clara cells from exposed lungs after 24 hr in culture, and (3) an increase in the number of bronchiolar cells in the S-phase after the first exposure to MC. The study also demonstrates the advantages of target cell isolation and study over whole lung biochemical investigation alone.

Administration, Inhalation↗
PubMed1992

Value of the Candida antigen assay in diagnosis of systemic candidiasis in burn patients.

The Cand-tec latex agglutination test was used to analyze 2,575 serum samples from 47 consecutive burn patients at risk for systemic candidiasis and serum samples from 24 nonhospitalized control subjects. One burn patient had systemic candidiasis documented by culture of a deep biopsy specimen. In addition, blood culture produced positive results in one patient with no other evidence of systemic candidiasis. Wound, sputum, mucous membrane, or gastrointestinal tract specimens were cultured in 25 of 47 (53%) patients with no evidence of systemic candidiasis. Surveillance cultures were negative in 19 (40%) patients and there were no signs of systemic candidial infection. The sensitivity of the Candida antigen titer was 100% at titers of greater than or equal to 1:2, greater than or equal to 1:4, greater than or equal to 1:8, and greater than or equal to 1:16. Specificity was 77% at titers of greater than or equal to 1:4, 94% at titers of greater than or equal to 1:8, and 100% at titers of greater than or equal to 1:16. The positive predictive value ranged from 6.0% at greater than or equal to 1:4 to 100% at greater than or equal to 1:16. The negative predictive value was 100% for all titer values. The Cand-tec antigen test shows poor specificity and poor positive predictive value for the detection of systemic candidiasis in burn patients.

Adolescent↗
PubMed1992

Management of corporal veno-occlusive dysfunction.

Veno-occlusive dysfunction has become a recognized cause of organic impotence. The existence of concomitant arterial and sinus smooth-muscle disease makes this disorder often difficult to diagnose. It rarely can be the sole etiology for impotence. The authors' experience in the treatment of this disorder in over 100 patients is presented. The authors rely on cavernosometry/pharmacocavernosometry/pharmacocavernosogr aphy and the color duplex Doppler screening test (to eliminate concomitant arterial disease) as the primary diagnostic tools. Twenty-two patients of 58 (38%) have achieved long-lasting success from the surgery so that they are able to have vaginal intercourse. Another 12 patients (21%) have been improved but must depend upon pharmacological injection therapy to obtain a sufficient erection for intercourse. There has been a 41% failure rate, and these are discussed.

Arterial Occlusive Diseases↗
PubMed1992

An in vitro model for studying the effects of slime and nonslime-forming Staphylococcus epidermidis contamination of intravenous catheters.

An in vitro model was developed to study the relationship between intravenous catheters, bacteria, and the subcutaneous tunnel. Studies of both slime-forming and nonslime-forming coagulase negative Staphylococcus epidermidis show that slime formation enhances capillary action of coagulase negative S. epidermidis. This offers a possible explanation of the increased virulence associated with slime-forming coagulase negative S. epidermidis in the clinical situation.

Agar↗
PubMed1991

Results of surgery for veno-occlusive disease.

Surgery directed at veno-occlusive dysfunction in impotency has evolved since 1981, following the recognition that vascular disorders are the major source of etiology of impotency. As the diagnostic tests for concomitant arterial disease have become more sophisticated, the results for pure veno-occlusive surgery have improved. Details of postoperative results in 60 of the author's patients are discussed along with other published results. The failure rate is 30-50%. Success includes those patients who can then obtain an erection with pharmacological agents who were unable to do so prior to surgery. A discussion of why the surgery fails is presented.

Erectile Dysfunction↗
PubMed1991

Vasculogenic impotence. Duplex and color Doppler imaging.

Varicoceles, although only occasionally symptomatic, are reported to occur in 20% to 50% of infertile or subfertile men. Ligation or occlusion of the spermatic vein in these patients has improved semen quality in many instances. Recently, it has been recognized that varicoceles can be bilateral or subclinical and thus detected only by imaging. Sonographic diagnosis of varicoceles and percutaneous occlusive therapy are reviewed in this article.

Color↗
PubMed1990

Clara cell cultures from the mouse and their reaction to bronchiolar toxins.

The major aim of this study was to determine if small numbers of freshly isolated mouse Clara cells could be used to rapidly screen the toxic effects of a number of diverse pulmonary toxins. A short-term (20 hr) culture of functionally competent (nitotetrazolium reductase positive) Clara cells was developed. In this culture the Clara cells were allowed to attach to an extracellular matrix in 96-well multiwell plates containing a culture medium of DCCM 1 and Ultroser G (0.4%). Pulmonary toxins (a total of 26 agents with concentrations ranging from 10(-7) M to 10(-3) M) were examined for their ability to reduce the attachment efficiency of functionally competent Clara cells and TD50 values (the amount of toxin required to reduce normal attachment efficiency by 50%) were calculated. With the possible exception of some halogenated hydrocarbons, the simple toxicity test in vitro correlated well with the known effects of the bronchiolar necrotic agents in vivo. For 13 compounds studied there was a direct correlation between TD50 values in vitro and LD50 values (mostly oral) in rodents in vivo, the correlation coefficient of the regression line being 0.783.

Animals↗
PubMed1989

Duplex and color Doppler sonographic evaluation of vasculogenic impotence.

One hundred eighty patients with suspected vasculogenic impotence were evaluated with conventional penile duplex sonography with spectral analysis and color Doppler imaging. Measurements of mean peak systolic and end-diastolic velocities were obtained from the cavernosal arteries before and after intracavernosal injections of papaverine. Sixty-one patients were examined with dynamic cavernosography and cavernosometry, and 12 patients were studied with selective internal pudendal and penile arteriography. All five patients with abnormal arteriography had mean peak systolic velocities in the cavernosal arteries of less than or equal to 25 cm/sec (sensitivity, 100%; 95% confidence interval, 48-100%) after the injection of papaverine. Six of the seven patients with normal arteriography had mean peak systolic velocities of greater than 25 cm/sec (specificity, 85.7%; 95% confidence interval, 42-100%) after injection of papaverine. By using data from a receiver-operating-characteristic curve, we determined that end-diastolic velocities in the cavernosal arteries of greater than or equal to 5 cm/sec after the injection of papaverine correctly identified patients with excessive venous leakage on cavernosometry; the sensitivity was 90% (95% confidence interval, 77-97%) and the specificity was 56% (95% confidence interval, 30-80%). The addition of color Doppler sonography made the detection of vessels easier and the correction of the Doppler angle more accurate, resulting in more rapid and accurate acquisition of data. Penile duplex sonography with spectral analysis and color Doppler imaging are sensitive and noninvasive means of examining patients with potential vasculogenic impotence.

Adolescent↗
PubMed1988

Correction of intrinsic penile chordee with a ventral penile graft of fascia lata.

Chordee is an abnormal curvature of the penis detected on erection. Congenital or primary curvature of the penis without hypospadias is, however, rare. There are two kinds of primary curvatures; those associated with a normal corpus spongiosum and those with a hypoplastic spongiosum. Secondary curvatures associated with Peyronie's disease or periurethral fibrosis associated with urethral stricture are more common in adults. Four nonhuman primates had successful correction of artificially induced chordee with a graft of fascia lata.

Animals↗
PubMed1988

Measurement of impotence by laser Doppler flowmetry and conventional methodology.

The problem of vasculogenic impotence was evaluated by laser Doppler flowmetry with the LD5000 capillary perfusion monitor to determine cutaneous penile blood flow in 25 men defined previously as impotent by Doppler ultrasound with penile brachial ratios of 0.63 +/- 0.14. Erotic visual stimulation for 1, 2 and 4 minutes did not statistically change the cutaneous flow as measured by laser Doppler flowmetry from its baseline of 20 mv. The dynamics of skin microcirculation in the penis may reflect changes in the deeper vessels and represent an alternate, dependable method to evaluate capillary perfusion.

Adult↗
PubMed1988

Venous surgery for impotence.

Venous surgery for impotence is in a dynamic state. The drainage of the corpora cavernosa normally occurs through the crural veins or the cavernous veins and the deep dorsal penile vein. Patients with drainage seen on cavernosography only into a superficial system that persists after injection of intracavernous vasoactive agents are likely to have good results if this drainage is eliminated. This type of patient is not common. A surgical approach that attempts to eliminate the deep dorsal penile system or the crural veins is not as successful. Perhaps subtle arterial disease, concurrent presence of neurologic disease, and collateralization all add to the significant failure rate. Many failures of spontaneous erection will, however, respond to intracavernous injection of vasoactive agents postoperatively. Deep dorsal vein arterialization probably should be reserved for those patients who have an arterial component to their impotence as well as a venogenic cause.

Erectile Dysfunction↗
PubMed1987

The fate of instilled pulmonary surfactant in normal and quartz-treated rats.

Naturally prepared radiolabelled pulmonary surfactant can be rapidly cleared from the alveolar surface to the lung tissue after intratracheal instillation into experimental rats. This clearance is both time- and dose-dependent, a large dose (10 mg/animal) becoming associated with lung tissue more rapidly than a smaller more physiological dose (0.75 mg/animal). The data indicate that extracellular dipalmitoyl-phosphatidylcholine, the major component of pulmonary surfactant, is not catabolized at the alveolar surface. Alveolar free cells (mainly macrophages) appear to play a minor role in surfactant clearance. Quartz-induced phospholipidosis does not lead to an alteration in the rate of bulk surfactant clearance from the alveolar surface, although the initial distribution of the removed phospholipid complex may change in relation to the enlarged heterogenous free cell population.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1987

Dynamic corpus cavernosography: effect of papaverine injection.

A study was done in 21 men to identify individuals with venous leakage as a cause of impotence. Combined pressure flow measurement and cinecavernosography were performed before and after the injection of papaverine into the corpora. After papaverine injection, erections and/or higher pressures occurred at lower flow rates in all the men. The venous drainage of the corpora decreased or disappeared in most subjects while the corpora became larger and contained more contrast material. The findings suggest that an active venous obstructive mechanism is important during erection, can be induced by the administration of papaverine, and should be evaluated in impotent men.

Adult↗