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Biomedical subjects

L Stewart

Publications and source records attributed to L Stewart.

At least 127 records · Page 7Linked to original sources
PubMed1989

Treatment of metastatic prostatic cancer with low-dose prednisone: evaluation of pain and quality of life as pragmatic indices of response.

Thirty-seven men with symptomatic bone metastases from prostate cancer that had progressed following earlier treatment with estrogens and/or orchidectomy were treated with low-dose prednisone (7.5 to 10 mg daily). The rationale for this treatment was that some patients might still have hormone-sensitive disease that was stimulated by weak androgens of adrenal origin, and that these androgens could be suppressed by prednisone through its negative feedback on secretion of adrenocorticotrophic hormone (ACTH). Response to treatment was assessed by requirement for analgesics, by the McGill-Melzack pain questionnaire, and by a series of 17 linear analog self-assessment (LASA) scales relating to pain and to various aspects of quality of life. Fourteen patients (38%) had improvement in indices used to assess pain at 1 month after starting prednisone, and seven patients (19%) maintained this improvement for 3 to 30 months (median, 4 months). Reduction in pain was associated with improvement in other dimensions of quality of life, and in the scale for overall well-being. Prednisone treatment led to a decrease in the concentration of serum testosterone in seven of nine patients where it was not initially suppressed below 2 nmol/L, and caused a decrease in serum levels of androstenedione and dehydroepiandrosterone sulfate in more than 50% of patients. Symptomatic response was associated with a decrease in serum concentration of adrenal androgens. We conclude that (1) low-dose prednisone may cause useful relief of pain in some patients with advanced prostatic cancer; (2) relief of pain was associated with suppression of adrenal androgens; and (3) measures of pain and quality of life can be used to assess possible benefits of systemic therapy in patients with metastatic prostate cancer.

Aged↗
PubMed1988

Risk factors for varicella zoster disseminated infection among adult cancer patients with localized zoster.

Varicella zoster (VZ) infection can be a highly morbid and potentially fatal disease among immunocompromised patients; 811 episodes of VZ infection among adult cancer patients seen at the Princess Margaret Hospital from 1970 to 1980, were identified. Seven hundred twelve patients with first episodes of localized VZ infection (zoster) were analyzed for potential risk factors for dissemination. Significant risk factors after univariate analysis included the diagnosis of Hodgkin's disease, decreasing age, chemotherapy within 6 months of VZ infection, and extensive tumor at initial tumor diagnosis. Complete tumor remission at the time of infection, previous radiotherapy, and breast or gynecologic cancer were associated with reduced risk in this analysis. After multivariate analysis the following factors were independently associated with increased risk: Hodgkin's disease (P less than 0.001), non-Hodgkin's lymphoma (P = 0.016), and head and neck cancer (P = 0.043). Complete tumor remission and previous radiotherapy were again related to a reduced risk of infection. This study identifies risk factors that define specific subgroups of adult cancer patients with zoster infections who are at increased risk for VZ dissemination. These factors may be useful in prospectively defining high-risk groups in the design of antiviral therapy trials and may have a role in deciding which cancer patients with zoster will benefit most from receiving antiviral therapy to prevent dissemination.

Adolescent↗
PubMed1988

Cholangiovenous reflux pathways as defined by corrosion casting and scanning electron microscopy.

Using corrosion casting and scanning electron microscopy of the rat biliary tree, we investigated the site and size of the pathways that allow bacteria to reflux from bile to blood. Nonobstructed rat biliary trees were injected retrograde with methylmethacrylate resin at a constant rate of 0.04 ml/min to volumes of 40, 60, 80, 120, 160, and 200 microliters. The infusion pressure was monitored and a pressure-volume curve was constructed. After polymerization and corrosion in 30 percent potassium hydroxide, the casts were examined with scanning electron microscopy. In addition, to identify the size of the reflux pathways, ceramic particles of 150 A, 1.7 mu, or 10 mu were added to the resin, and the studies were repeated. Finally, intact livers with casted biliary trees were processed and studied by scanning electron microscopy without corrosion. Scanning electron microscopy demonstrated fine anatomic detail of the cholangiovenous reflux pathway. At 40 microliters (20 cm water pressure), normal biliary radicals were filled. Between 40 and 80 microliters (20 to 50 cm water pressure), the cast material refluxed from the bile ductules into the spaces of Mall and Disse and then into the hepatic sinusoids. Filling of sinusoids continued at volumes between 80 to 160 microliters, and filling of collecting veins was seen above 160 microliters. Particles of 1.7 mu and smaller readily refluxed, but there was no sinusoidal reflux of casting material that contained particles of 10 mu. Casting without corrosion showed that the liver parenchyma remained intact. There was no evidence of reflux across hepatocytes. This study shows that cholangiovenous reflux occurs directly from bile ductules through the spaces of Mall and Disse into the hepatic sinusoids. The pathways measure between 1.7 and 10 mu. Since this is the path of least resistance, it may be of greater importance in the reflux of bacteria and toxins than other high-resistance pathways, for example, biliary canaliculi, tight junctions, or hepatocytes.

Animals↗
PubMed1988

Varicella-zoster infection in adult cancer patients. A population study.

In a retrospective review of varicella-zoster (V-Z) Infections in adult cancer patients, 766 episodes of V-Z Infection were studied among 740 patients seen at a large comprehensive cancer center from 1972 to 1980. The highest risk of infection was present among patients with lymphoma and leukemia. The risk of dissemination of V-Z Infection was significantly associated with the presence of active tumor at the time of Infection. The site of the primary tumor correlated with the site of subsequent zoster Infection among patients with breast cancer, cancer of the respiratory tract, and gynecologic cancer. Pain attributable to V-Z Infection was present in a large majority of episodes. The median time from the completion of therapy to the onset of Infection was seven months for patients receiving radiotherapy and less than one month for those receiving chemotherapy. Various attributes of this study group were compared with those of previously studied cancer and noncancer populations.

Adolescent↗
PubMed1987

Pigment gallstones form as a composite of bacterial microcolonies and pigment solids.

Although previous studies have suggested that bacteria may contribute to pigment gallstone formation, the current experiments provide evidence that bacteria have a central role in this process. The studies included scanning electron microscopy (SEM) of gallstones, measurements of bacterial adherence to gallstones in vitro, and determination of glycocalyx elaboration by biliary bacteria. Gallstones from 85 patients were studied under SEM. Twenty-five (78%) of 32 pigment stones had evidence of bacterial microcolonies throughout the interior of the stones. Bacteria were absent from the interior of all 35 cholesterol stones studied. Composite stones (stones with separate pigment and cholesterol portions) showed evidence of bacteria within the pigment portions in 14 (78%) of 18 cases. Biliary bacteria adhered to the surface of pigment gallstones in vitro in 35 (90%) of 39 cases, compared with three (8%) of 39 cholesterol stones. Glycocalyx was elaborated by bacteria isolated from nine (82%) of 11 patients with either pigment or composite gallstones. One (33%) of three bacterial species from patients with cholesterol gallstone disease produced glycocalyx. These studies indicate that most pigment gallstones obtained from patients in Western cultures form as a composite of bacteria, bacterial glycocalyx, and pigment solids. Bacteria were found in the majority of black as well as brown pigment stones. These findings serve as the basis of a new theory of pigment stone formation in which bacteria and glycocalyx are postulated to be responsible for the precipitation and subsequent agglomeration of bilirubin pigment. These results also suggest that sepsis is more common in pigment gallstone disease because the stones can serve as a sanctuary for bacteria.

Adult↗
PubMed1986

Transected dorsal column axons within the guinea pig spinal cord regenerate in the presence of an applied electric field.

Using an implanted battery and electrodes, we have imposed a weak, steady electrical field across partially severed guinea pig spinal cords. We have analyzed regeneration of dorsal column axons in experimental animals and sham-treated controls at 50-60 days postinjury by anterograde filling of these axons with the intracellular marker horseradish peroxidase and by employing a marking device to identify precisely the original plane of transection (J. Comp. Neurol. 250: 157-167, '86). In response to electric field applications, axons grew into the glial scar, as far as the plane of transection in most experimental animals. In a few animals axons could be traced around the margins of the lesion (but never through it). Moreover, these fibers returned to their approximate positions within the rostral spinal cord before turning toward the brain. In sham-treated controls, ascending axons were found to terminate caudal to the glial scar, and rarely were any fibers found within the scar itself. Axons were never observed to cross into the rostral cord segment. These findings suggest that an imposed electrical field promotes growth of axons within the partially severed mammalian spinal cord, that a steady voltage gradient may be an environmental component necessary for axonal development and regeneration, and that some component(s) of the scar impede or deflect axonal growth and projection.

Animals↗
PubMed1986

Chorionic biopsy for prenatal diagnosis. An investigative study of 110 cases.

The results of experimental chorionic villus biopsies in 100 first-trimester pregnancies in patients who were undergoing suction termination are presented, together with the results of biopsies from 10 continuing pregnancies. The trends that were observed confirm previous findings that chorionic biopsy can be employed to diagnose chromosomal, genetic and biochemical disorders in the first trimester of pregnancy. The risks surrounding the procedure and the need for continuing assessment and development are discussed.

Abortion, Spontaneous↗
PubMed1985

Abnormally high sweat osmolality in children with Down's syndrome.

There are few data on sweat analysis in Down's syndrome. We studied 25 children with Down's syndrome and obtained sweat samples by pilocarpine iontophoresis. Sweat osmolality was elevated in Down's syndrome compared to normal. The results of sweat testing must be regarded with caution when cystic fibrosis is suspected in children with Down's syndrome.

Child, Preschool↗