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Biomedical subjects

M Bolton

Publications and source records attributed to M Bolton.

15 recordsLinked to original sources
PubMed2006

Contact area inside the distal radioulnar joint: effect of axial loading and position of the forearm.

BACKGROUND: A biomechanical study was performed to define the normal profiles of contact area inside the distal radioulnar joint and how these profiles change as a result of damage to the distal radioulnar ligaments. METHODS: Twelve cadaver arms were used and a custom-made jig was designed to allow axial loading of the hand. Tekscan sensor film was used to measure the contact area inside the joint. Measurements were taken with different loads and in different positions of the forearm. The same measurements were taken after dividing either the volar or dorsal distal radioulnar ligament. Finally the measurements were repeated after reconstruction of the divided ligament. FINDINGS: The contact area increases with axial loading of the hand and is greater in supination than pronation. Division of a single distal radioulnar ligament increases the contact area inside the distal radioulnar joint (123% of normal) and reconstruction of the divided distal radioulnar ligament restores the contact patterns towards the normal values (113% of normal). INTERPRETATION: The results show that axial loading of the hand and position of the forearm has a significant effect on the contact area inside the distal radioulnar joint. The study also shows that injury of the distal radioulnar ligament disturbs the normal profiles of contact.

Aged↗
PubMed2006

The load-bearing characteristics of the forearm: pattern of axial and bending force transmitted through ulna and radius.

A biomechanical study was performed on 12 cadaveric arms to define the normal profiles of force transmission through the ulna and radius and demonstrate the effect on these of simulated injury of the distal radioulnar joint (DRUJ). Strain gauges were used to measure the axial and bending forces transmitted through each bone. Axial force transmitted through the ulna is, broadly, reciprocal to that seen in the radius, with the greatest force seen in supination. In all 12 arms, axial loading of the hand created an anterior bending force (to create a posterior convexity) in the distal radius. Axial loading of the hand created an anterior bending force in the distal ulna for half the specimens and a posterior bending force in the remaining half. Division and division with reconstruction of either the volar or the dorsal distal radioulnar ligament (DRUL) had no significant effect on force transmission through the ulna and radius, while excision of the ulnar head significantly disrupted the profiles of the axial and bending forces.

Aged↗
PubMed2002

Avian dark cells.

Dark cells (DCs) of mammalian and non-mammalian species help to maintain the homeostasis of the inner ear fluids in vivo. Although the avian cochlea is straight and the mammalian cochlea is coiled, no significant difference in the morphology and/or function of mammalian and avian DCs has been reported. The mammalian equivalent of avian DCs are marginal cells and are located in the stria vascularis along a bony sheet. Avian DCs hang free from the tegmentum vasculosum (TV) of the avian lagena between the perilymph and endolymph. Frame averaging was used to image the fluorescence emitted by several fluorochromes applied to freshly isolated dark cells (iDCs) from chickens (Gallus domesticus) inner ears. The viability of iDCs was monitored via trypan blue exclusion at each isolation step. Sodium Green, BCECF-AM, Rhodamine 123 and 9-anthroyl ouabain molecules were used to test iDC function. These fluorochromes label iDCs ionic transmembrane trafficking function, membrane electrogenic potentials and Na+/K+ ATPase pump's activity. Na+/K+ ATPase pump sites, were also evaluated by the p-nitrophenyl phosphatase reaction. These results suggest that iDCs remain viable for several hours after isolation without special culturing requirements and that the number and functional activity of Na+/K+ ATPase pumps in the iDCs were indistinguishable from in vivo DCs. Primary cultures of freshly iDCs were successfully maintained for 28 days in plastic dishes with RPMI 1640 culture medium. The preparation of iDCs overcomes the difficulty of DCs accessability in vivo and the unavoidable contamination that rupturing the inner ear microenvironments induces.

Animals↗
PubMed2001

Weekly docetaxel and estramustine in patients with hormone-refractory prostate cancer.

The combination of docetaxel and estramustine has exhibited synergistic activity both in prostate cancer cell lines and in patients with hormone-refractory prostate cancer (HRPC). Based on these promising preclinical and phase I/II data, we conducted a study of weekly docetaxel and estramustine in patients with metastatic HRPC and a poor performance status. A total of 30 patients received (1) a 3-day course of oral estramustine during weeks 1 and 2 of each 3-week cycle plus (2) docetaxel, 35 mg/m(2) intravenously on day 2 of weeks 1 and 2. The median number of cycles per patient was 5, ranging from 1 to 22. The median patient age was 74 years (range, 61 to 90 years), and the median baseline Karnofsky performance status was 60% (range, 50% to 80%). Twenty-three patients (76%) had a > or =50% decrease in serum prostate-specific antigen (PSA); 17 (56%) of these patients had a > or =75% decrease in PSA. Pain scores and performance status likewise improved in 70% of patients. Three complete responses and four partial responses were observed among 12 patients with measurable disease. Toxicities were primarily nonhematologic in nature, with the most common being grade 1 through 3 nausea, asthenia, diarrhea, and edema. Given the activity and tolerability of weekly docetaxel and estramustine in this study, this regimen appears to be more suitable than previously studied docetaxel/estramustine administration schedules for treating metastatic HRPC in elderly patients with a poor performance status.

Adenocarcinoma↗
PubMed2001

Squamous cell carcinoma of the colon with an elevated serum squamous cell carcinoma antigen responding to combination chemotherapy.

Primary squamous cell colorectal carcinomas are uncommon, and their characteristics are not well known. They seem to occur most commonly in the fifth decade of life with a slight predominance for men. The most commonly reported anatomic locations are the rectum and the proximal colon. Clinical features and common diagnostic methods do not easily differentiate squamous cell colorectal carcinomas from adenocarcinomas. Because of their extremely rare occurrence, it is difficult to study their natural course, clinical behavior, and response to therapy. This report presents the case of a pure squamous cell colorectal cancer and provides a brief review of the literature, which includes 60 previously published cases. The case of a patient with T3N2M0 primary squamous cell carcinoma of the rectosigmoid colon, which was initially treated with abdominoperineal resection followed by adjuvant chemotherapy and radiation, is presented. During the follow-up, an elevated squamous cell carcinoma antigen (SCC Ag) level led to restaging computed tomography scans, which confirmed recurrent metastatic disease in the liver. Response to chemotherapy with a decrease in tumor size correlated with a decrease in the serum SCC Ag level. Although SCC Ag has been used as a tumor marker for squamous cell cancers of the lung, head and neck, uterine cervix, and esophagus, this is the first reported case of a squamous cell colon carcinoma presenting with an elevated SCC Ag at the time of recurrence. In addition, this patient showed an objective partial response to combination chemotherapy, with a decrease in the serum level of this tumor marker.

Antigens, Neoplasm↗
PubMed2001

An adverse interaction between warfarin and capecitabine: a case report and review of the literature.

Warfarin is one of the most commonly used oral anticoagulants in the clinic. It is well established that a wide range of antineoplastic drugs interact with warfarin, resulting in altered coagulation parameters and/or bleeding sequelae. While altered coagulation parameters have been observed in patients taking the oral 5-fluorouracil prodrug, capecitabine, in combination with warfarin, no report to date has described clinically overt evidence of bleeding. Herein, we report 2 cancer patients who presented with bleeding episodes that most likely resulted from an adverse interaction between capecitabine and warfarin after 6 weeks of concomitant therapy. In each case, there was a marked elevation in both the prothrombin time and international normalized ratio (> 10), with subsequent gastrointestinal bleeding. The exact mechanism of this interaction is yet unknown, but it is possible that capecitabine might, in some manner, reduce the hepatic metabolism of warfarin. Close monitoring of coagulation parameters is recommended for all patients receiving concomitant warfarin and capecitabine, with appropriate adjustment of warfarin dosage. The nature and extent of this interaction requires further investigation.

Aged↗
PubMed1998

What mothers in the Women, Infants, and Children (WIC) program feel about WIC and immunization linkage activities. A summary of focus groups in Wisconsin.

BACKGROUND: Although studies indicate that strategies to improve immunization coverage among preschool-age children enrolled in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) are effective, the attitudes of parents of children enrolled in WIC toward the linkage between WIC and immunization programs is unknown. OBJECTIVE: To gain a better understanding of how parents using WIC resources feel about the association of WIC and immunization services, their attitudes toward WIC immunization activities, factors that may cause clients to drop out of the program, and the effects of racial background on parent attitudes. PARTICIPANTS AND METHODS: We conducted 8 focus group sessions with mothers whose children receive WIC services in Milwaukee, Wis. Mothers were between 18 and 35 years old, with at least 1 child between 6 and 24 months of age. The 47 mothers participating were each assigned to 1 of 8 focus groups, including 2 groups each of Asian, white, African American, and Hispanic mothers. A systematic content analysis was conducted for themes and key points within and across ethnic groups. RESULTS: Socially disadvantaged mothers reported their overall experiences in WIC to be very positive. Lengthy waiting time during a WIC visit was identified as the most important barrier to participation. Mothers believed strongly that it was the responsibility of parents to get their children vaccinated, but that WIC staff and the primary care provider should work together to remind parents when vaccinations were due. Mothers expressed very positive attitudes toward the linking of WIC and immunization activities. Telephone reminders and education were mentioned as the best ways to encourage mothers to get their child vaccinated on time. Immunization linkage activities and the requirement that a parent report to a WIC center more frequently if the child was underimmunized were not mentioned as reasons for dropping out of the WIC program; indeed, more frequent visits to a WIC center were actually viewed as a potentially effective strategy by several mothers. Some mothers found obtaining immunizations and WIC services at the same time and place to be very convenient. There did not seem to be any significant differences among ethnic groups in attitudes toward immunization linkage activities being performed in WIC. CONCLUSIONS: Mothers with preschool-age children enrolled in WIC feel that the linkage of immunization activities with WIC services is a helpful way to improve the health of their children. This linkage was not identified as a contributing factor for leaving the WIC program.

Adolescent↗
PubMed1996

Neural circuitry of capsaicin-sensitive afferents innervating submucosal arterioles in guinea pig ileum.

The circuitry of capsaicin-sensitive nerves innervating submucosal arterioles in the guinea pig ileum was examined. The orientation of in vitro submucosal preparations in a double-chamber bath was varied so that nerves on differing segments of arterioles could be stimulated with capsaicin. Capsaicin-evoked dilation of preconstricted arterioles was recorded using videomicroscopy. Superfusion of capsaicin onto either proximal or distal segments of a parent arteriole divided between the chambers evoked a dilation in the opposite chamber (63 and 58%, respectively) but had no effect on extrinsically denervated preparations. When the divider separated the vascular arcades joining the two parent arterioles on the opposite or same side of the intestine, capsaicin evoked little or no response (8 and 11%, respectively). Capsaicin stimulation confined to one branch of a single vessel dilated the opposite branch (42%). In preparations with adjacently attached mucosa, application of capsaicin to the mucosa dilated arterioles in the opposite chamber. These findings suggest that capsaicin stimulation of the mucosa evokes dilation of arterioles through a submucosal reflex and that both afferent and efferent elements are confined to the submucosa and mucosa.

Animals↗
PubMed1991

Molecular cloning and characterization of a Candida tsukubaensis alpha-glucosidase gene in the yeast Saccharomyces cerevisiae.

The molecular cloning of an alpha-glucosidase gene isolated from a Candida tsukubaensis (CBS 6389) genomic library in Saccharomyces cervisiae is reported. The cloned gene is contained within a 6.2 kb Sau3A DNA fragment and directs the synthesis and secretion of an amylolytic enzyme into the extracellular medium of the recombinant host, S. cerevisiae. The cloned enzyme was found to have an unusually broad substrate specificity and is capable of hydrolysing alpha-1,2, alpha-1,3, alpha-1,4 and alpha-1,6 linked, as well as aryl and alkyl, D-glucosides. On the basis of its substrate specificity profile, the cloned enzyme was classified as an alpha-glucosidase (E.C. 3.2.1.20). It has a pH optimum in the range 4.2-4.6, a temperature optimum of 58 degrees C and is readily inactivated at pasteurization temperature (60 degrees C). Southern blot analysis failed to reveal any homology between the cloned gene and genomic DNA isolated from other well characterized amylolytic yeasts. A rapid plate-assay, based on the utilization of a chromogenic substrate X-alpha-D-glucoside to detect the expression of the cloned alpha-glucosidase in S. cerevisiae transformants, was developed.

Blotting, Southern↗
PubMed1976

Seroepidemiology of amebiasis in the Orang Asli (Western Malaysian aborigine) and other Malaysians.

The indirect hemagglutination test was used to study antibody titers to Entamoeba histolytica in different Malaysian populations. Eighty-seven percent of Orang Asli (western Malaysian aborigines) adults and 79% of Orang Asli children with acute amebic dysentery were seropositive. However, significantly fewer children (39%) with amebic dysentery had high titer responses (titer greater than or equal to 1:1,280) than did adults with amebic dysentery (76%). No correlation between proctoscopic severity and amebic titer was found. Forty-four percent of asymptomatic family members were seroresponders. Satak, an Orang Asli village located near towns, had significantly more seroresponders (32%) than did the isolated, deep jungle village, Belatim (4%).

Adult↗