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Biomedical subjects

R L Meyer

Publications and source records attributed to R L Meyer.

At least 73 records · Page 4Linked to original sources
PubMed1987

Regional adjuvant irradiation for adenocarcinoma of the cecum.

Forty patients with adenocarcinoma of the cecum who underwent right hemicolectomy received regional irradiation for 40-45 Gy/4-5 weeks and weekly 5-Fluorouracil (5-FU). Thirty-four patients received this adjuvant therapy: 12, 10, 5, 4 with Stage B2, B3, C2, C3, respectively, and 3 with abdominal metastasis. Another six patients were similarly treated for palliation because of tumor bed recurrences. Patients were followed for a median of 4 years, 21/31 patients in the adjuvant group with Stage B and C were free of disease with a median survival of 48 months (63% 5-year actuarial disease-free survival). The total local failure rate among the adjuvant group for Stage B and C was 4/31 (13%) with local failure alone occurring in 1 of 4 patients (3%). In the patients treated at our Hospital, there was significant improvement in the 5-year actuarial survival (p = 0.001) for patients with lymph node metastases who received adjuvant irradiation compared to surgery-alone. Acute radiation enteritis occurred in seven out of 40 patients (17.5%) and was severe in 2 (5%). There were no delayed complications. We conclude that adjuvant therapy markedly lowered regional recurrence and seems to improve survival in patients with lymph node metastasis when compared to a group of patients treated by surgery alone in the same institution.

Adenocarcinoma↗
PubMed1987

Ovarian carcinoma: results of radiation therapy and chemotherapy in 83 patients.

Eighty-three patients with ovarian cancer who had undergone radiation therapy, chemotherapy, or both were evaluated. Eight patients had FIGO stage I, 12 had stage II, 61 had stage III, and two had stage IV disease. In 60 patients, radiation was delivered with open abdominopelvic field (30 Gy over 4 weeks), with or without a pelvic boost dose. Fifty-five patients received a combination of chemotherapeutic agents, and 30 received a single agent as initial therapy. The patients were divided into three groups. The 26 patients in group 1 received primary radiation therapy with or without adjuvant single-agent chemotherapy. The 34 patients in group 2 underwent radiation therapy after chemotherapy failed. The 23 patients in group 3 received combination chemotherapy. Nineteen patients (23%) achieved complete remission--eight from group 1, two from group 2, and nine from group 3. The 5-year actuarial survival for group 1 was 41% but was only 16% for both groups 2 and 3 combined (P = .026). Primary radiation therapy, with or without adjuvant single-agent chemotherapy, was superior to combination chemotherapy in patients with ovarian cancer.

Actuarial Analysis↗
PubMed1987

Dense HRP filling in pre-fixed brain tissue for light and electron microscopy.

The use of neuroanatomical markers in tissues that have been pre-fixed has been virtually ignored, even though this approach could offer certain advantages over in vivo methods, in terms of convenience of application and choice of markers. We have found that HRP can be used on well-fixed brains of cats and goldfish to fill neurons, dendrites, axons, terminals, glial cells, and glial processes for high-resolution light microscopy and electron microscopy. Best results were obtained using brains that were perfusion-fixed with 2.5% depolymerized paraformaldehyde and 1.5% glutaraldehyde. Two methods of HRP application were used: optically guided injections of microliter quantities into various regions of cat brain, and optic nerve fills in goldfish by attaching an HRP-filled polyethylene tube for periods of 1 day to 2 weeks. HRP applied in these ways to pre-fixed tissue was found to fill neurons or glial cells with solid label in the anterograde and retrograde directions.

Animals↗
PubMed1986

Implantable venous access devices: an alternative method of extended cancer care.

The advent of totally implantable venous access devices (TIVADs) is changing the method of treatment for those chronically ill patients who require long-term chemotherapy or narcotic infusion. TIVADs eliminate the problem of limited peripheral vein access with little risk of complication. At Good Samaritan Hospital in Cincinnati, Ohio, we have implanted 30 TIVADs (3 Infuse-A-Ports and 27 Port-a-Caths) for a total of 4,502 patient days. This report documents our experience with the implantation and utilization of TIVAD systems.

Adult↗
PubMed1985

Topography of regenerating optic fibers in goldfish traced with local wheat germ injections into retina: evidence for discontinuous microtopography in the retinotectal projection.

A small injection of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) was injected into dorsal or ventral peripheral retina in normal goldfish and in goldfish with prior optic nerve crush. Serial sections of tectum were subsequently taken for horseradish peroxidase (HRP) histochemistry 18 hours after injection and studied with light microscopy and densitometric reconstructions. In normals, a small, sharply delineated patch of product 200-300 microns wide was observed at the appropriate medial or lateral periphery of tectum. This product filled the entire SFGS, the main optic termination layer, and fell off abruptly at its edges. No labelling was detected in the optic pathways. In regenerates at about 20 days after nerve crush, these retinal injections yielded product that was dispersed across 1,000 microns or more of tectum but not in a uniform fashion. The densest product was biased toward the appropriate tectal position while product of intermediate density was mainly distributed along a path from the anterior end of tectum to this region. Product in the inappropriate half of tectum was much lighter and typically fiberlike in appearance. By about 40 days, product had condensed considerably at roughly the correct region of tectum but it was not as sharply delimited as in normals. Dense label occupied a single area about twice that of normals and exhibited flanking regions of light label extending for several hundred micrometers. At 59-148 days, a further condensation was observed but into more than one patch of product. The patches were of variable size and consisted of sharply delimited dense product which filled the entire SFGS at each position. Morphologically, these patches bore a remarkable resemblance to the ocular dominance columns previously seen in this system.

Animals↗
PubMed1984

Postoperative adjuvant irradiation and 5-fluorouracil for adenocarcinoma of the cecum. A pilot study.

Twenty-one patients with adenocarcinoma of the cecum were treated in a pilot study between October, 1972 and June, 1982 by right hemicolectomy and received adjuvant postoperative irradiation (40-45 Gy/4-5 weeks) and 5-Fluorouracil (5-FU). There were 15, 4, and 2 patients with Stages (Astler-Coller) B2, C2, and D, respectively. There was no major morbidity nor mortality attributable to the adjuvant therapy. Patients were followed for a minimum of 15 months. Fifteen patients are alive and disease-free, with a median survival of 34 months (range, 17-79). There were no significant differences in the median survival or incidence of distant metastases when the adjuvant therapy group was matched by sex, age, and stage of disease with a group of patients treated by right hemicolectomy alone. There was a lower local failure rate in the adjuvant group compared with the surgery-alone group (5% versus 19%) (P less than 0.2). These data suggest that adjuvant therapy for cecal carcinoma is feasible, safe, and may reduce local failures and possibly improve survival in high-risk patients. It deserves further investigation so that a definite conclusion may be drawn.

Adenocarcinoma↗
PubMed1984

Target selection by surgically misdirected optic fibers in the tectum of goldfish.

This study tested the capacity of regenerating optic fibers to read tectal markers and thereby grow to their appropriate tectal loci when initial position, optic pathway, and interfiber interactions are eliminated as useful cues. The stability of these markers with long-term optic denervation of the tectum was also examined. In adult goldfish optic fibers innervating lateroposterior optic tectum were dissected free of tectum and inserted into the medial anterior region of the opposite "host" tectum. Normally, fibers at this position either innervate medial anterior tectum or follow the medial division of the optic pathway into medioposterior tectum. Host tectum was denervated of all other optic fibers by enucleating its contralateral eye either at the time of the deflection or at various times up to 18 months prior to deflection. The regeneration of these deflected fibers into host tectum was examined by autoradiography and electrophysiology at 1 to 11 months later. At the insertion site deflected fibers split into two groups of roughly equal size. One group directly entered the optic layers of medial tectum and grew posterolaterally across the medial half of tectum into the lateral half. The second group followed an almost direct path to the lateral tectum, sometimes traversing through the deep cell layers of tectum in which optic fibers are not usually found. These fibers subsequently entered the optic layers at the lateral edge of tectum and grew posteriorly. This second path was not seen in controls in which optic fibers from medioposterior tectum were similarly deflected. Instead growth was almost entirely posteriorly directed. On the average by 1.5 months deflected lateroposterior fibers were preferentially distributed in the lateral half of the tectum. Densitometric measurements indicated nearly a 4-fold difference in lateroposterior compared with medial posterior labeling. By contrast, controls in which medial posterior fibers were deflected had 4 times more grains medially than laterally. There was also a posterior over anterior preference, but this was weak. There was no suggestion that long periods of optic denervation prior to deflection or long postoperative periods after deflection of lateroposterior fibers diminished the lateral over medial preference. These findings support the idea that stable tectal markers exist which are differentially read by medial and lateral optic fibers. However, in no case was the innervation by deflected fibers as selective as in the normal projection.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Eye dominance columns from an isogenic double-nasal frog eye.

Removing the posterior (temporal) two-thirds of the Xenopus eye bud produces a remaining fragment, which becomes round and grows to a normal adult size eye. Electrophysiological and anatomical analyses showed that each of the two halves of this eye projected across the entire optic tectum in mirror image (double-nasal) fashion, and that fibers from each half-eye sorted out to form eye dominance stripes on the tectum. That both halves of the mirror-symmetric map were derived from only one animal, and from only one side of the head, rules out global markers such as right versus left and histocompatibility differences as causing the formation of these stripes.

Animals↗
PubMed1983

Tetrodotoxin inhibits the formation of refined retinotopography in goldfish.

One optic nerve of mature goldfish was crushed in the orbit and allowed to regenerate. During regeneration impulse activity was eliminated by periodic intraocular injections of tetrodotoxin (TTX). At 32-104 days, the retinotopography of the retinotectal projection was measured autoradiographically by intraocular [3H]proline injections simultaneous with either small (10-20 degrees sector) or half retinal mapping lesions. TTX had no effect on the time-course and quality of the regeneration of gross topography seen with half retina mapping, but indefinitely inhibited higher order (refined) retinotopography normally seen by 2 months with retina sector mapping.

Action Potentials↗
PubMed1983

Curative and palliative radiotherapy of bladder cancer. A retrospective study of 11 years experience.

A total of 119 patients with bladder cancer were irradiated over a period of 11 years. Fifteen had Stage B1, 15 B2, 38 C, 9 D1, 23 D2, and 19 D3. The pelvis, bladder, or both received less than or equal to 7,000 rad (70 Gy) in 7 weeks in 78 patients treated with curative intent (Group I) and less than or equal to 5,000 rad (50 Gy) in 5 weeks in 41 patients treated for palliation (Group II). Major complications developed in 3 patients due to irradiation and were fatal in 2, while 22 had minor, self-limited complications which were often related to the technique used. In Group I, the 3- and 5-year disease-free survival rates were 18% and 14%, respectively, whereas only 3% of Group II patients survived 3 years; however, reasonable palliation was achieved in a large percentage of cases. Superficial lesions (B1) can be cured with irradiation (60% 5-year survival). Other prognostic factors are presented.

Adult↗
PubMed1982

Tetrodotoxin blocks the formation of ocular dominance columns in goldfish.

Optic fibers from both eyes were made to regenerate simultaneously into one tectum in goldfish. Autoradiography at various times later revealed that regenerating left and right fibers overlapped extensively for up to 4 weeks and subsequently segregated into eye dominance columns by 8 weeks. Continuous tetrodotoxin treatment of both eyes prevented the formation of columns for up to 13 weeks and was equally effective if begun at 6 weeks. When tetrodotoxin treatment was stopped after 11 weeks, columns subsequently formed in the next 3 weeks. Blockade of only one eye did prevent column formation at 8 weeks.

Animals↗