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Biomedical subjects

M J Edwards

Publications and source records attributed to M J Edwards.

At least 199 records · Page 11Linked to original sources
PubMed1989

Isolated limb perfusion for stage I melanoma of the extremity: a comparison of melphalan and dacarbazine (DTIC).

Isolated limb perfusion (ILP) for melanoma of the extremity was first used clinically more than 30 years ago. Although ILP with chemotherapeutic agents has become routine practice in many oncologic centers, few studies have evaluated the therapeutic efficacy of particular agents. Two consecutive groups of 100 patients with stage I extremity melanoma of 1.5 mm thickness or greater were treated by ILP with either melphalan (L-PAM) or dacarbazine (DTIC). Demographics, clinical and pathologic stage, disease site, and complications were similar in both groups. No significant difference in the overall incidence of recurrent disease at two years was found between patients treated with either DTIC or L-PAM (22% vs 16%, respectively; P = .28). Patients who had perfusion with L-PAM, however, had a lower incidence of in-transit metastasis and recurrence at the scar than those having DTIC therapy (4% vs 12%, P = .06) at two years of follow-up. This preliminary report suggests that L-PAM may be more effective than DTIC in controlling scar recurrences and in-transit metastasis. Continued follow-up of this series of patients, with further analysis of patterns of recurrence and disease-free and overall survival at five years, will be necessary to better define the relative efficacy of L-PAM and DTIC in isolated limb perfusion.

Adult↗
PubMed1989

Surgical aspects of lymphoma.

Improvements in histologic classification, staging and multimodality therapy have dramatically changed the natural history of patients with lymphoma. Systematic staging accurately defines the extent of disease and minimizes the toxic effects of excessive treatment. Surgical diagnosis and staging with laparotomy provide the basis for choosing methods of definitive radiotherapy and chemotherapy for selected patients. Patients with extranodal disease in early stages may be treated effectively by surgical excision.

Hodgkin Disease↗
PubMed1988

Management of aortic prosthetic infections.

Infections of aortic vascular prostheses remain a dreaded complication. Although removal of the graft has generally been recommended in the literature, the role of lesser procedures, the need for alternate revascularization, and a precise plan of attack are ill defined. We have treated 18 patients with infection of aortic prostheses. Specific risk factors potentially promoting infection included reoperation, septic complications, or gastrointestinal entry at the time of graft placement. Clinical signs of infection included chronic draining sinus in eight patients, localized groin abscess in three patients, groin swelling in four patients, gastrointestinal bleeding in two patients, and pseudoaneurysm in one patient. Treatment by local therapy, including catheter irrigation of sinus tracts, debridement, and local antibiotics, resulted in failure in eight of nine patients. If the sinogram of a groin sinus showed no communication with the body of the graft, resection of a graft limb was successful in 66 percent of the patients. If the sinus communicated with the body of the graft, total resection was mandatory. When total excision was necessary, all patients required revascularization by means of an extraanatomic bypass. The mortality rate was 33 percent and was primarily due to bleeding fistulas. An aggressive approach to this serious problem with early graft excision is encouraged.

Aged↗
PubMed1988

Economic impact of reducing hospitalization for mastectomy patients.

In 1985, two policies designed to reduce hospitalization charges for mastectomy patients were instituted at the M.D. Anderson Cancer Center at Houston. The first was a policy of "same-day" admissions for elective surgery patients, and the second was early postoperative discharge for mastectomy patients with suction catheter drains in place. The economic savings resulting from these policies was analyzed by comparing demographics, operation, stage of disease, hospital stay, hospital charges, and complications for two groups of patients. Fifty-nine consecutive mastectomy patients treated between 1983 and 1984, before these policy changes, had "standard management" consisting of hospital admission 24 hours before surgery and discharge only after the surgical drains were removed. Sixty-one consecutive mastectomy patients treated between 1986 and 1987, after these policy changes went into effect, were admitted from the recovery room after surgery and were discharged with drainage catheters in place, usually within 72 hours. All operations were performed by the same faculty surgeon as a representative experience of the General Surgery faculty. The average hospital stay was reduced from 10.5 to 4.3 days. A mean 39% reduction in hospital charges (from $4867.00 to $2981.00) was achieved by instituting the policies of "same-day" admission and early postoperative discharge with drainage catheters in place. Complication rates were not changed. Implementation of this policy resulted in an estimated savings of $750,000.00 in the hospital care of approximately 400 patients treated at the M.D. Anderson Cancer Center at Houston each year. Adjustments in patient care delivery systems from a predominantly inpatient to an outpatient setting required changes in outpatient nursing responsibilities (although not in new personnel). Patient education and written instructions for home care of surgical wounds and drainage catheters were essential for implementing an early discharge policy. With these facts in mind, hospital admission on the day of operation and early postoperative discharge with drainage catheters in place should be the goal for most mastectomy patients.

Cancer Care Facilities↗
PubMed1987

Heat shock and thermotolerance during early rat embryo development.

Effects of heat shock on the development of early pre-somite embryos have been studied using cultured rat embryos. The results illustrate the sensitivity of the developing head and brain to elevated temperatures prior to neural tube closure and the capacity of embryos to acquire thermotolerance. Embryos exposed briefly to an elevated temperature (43 degrees C for 7.5 min) developed severe craniofacial defects including microphthalmia, microcephaly, gross reduction of the forebrain region, and open neural tubes. In contrast, a nonteratogenic heat shock (42 degrees C for 10 min) caused embryos to acquire thermotolerance during a 15-min recovery period at 38.5 degrees C. Acquired thermotolerance was effective in protecting embryos from a subsequent more severe heat treatment which would have been teratogenic in an unprotected embryo. Recovering embryos mounted a heat shock response as evidenced by the induction of a 71 kilodalton heat shock protein. Activation of the heat shock response was not a teratogenic event in the developing embryo.

Animals↗
PubMed1987

Three-dimensional reconstruction of tissue using computer-generated images.

In the study of brain ventricles for both teaching and research, it is often of considerable advantage to graphically display the reconstructed shape of the specimen. This paper describes the making of two-dimensional serial cross-sections and their storage for subsequent manipulation and display on a personal computer; the three-dimensional (3D) reconstructions may have hidden lines removed and various parts coloured for definition of areas of interest, for example the density and position of pyknotic (dead) nuclei. Current research involved the investigation of the effects of maternal hyperthermia on early embryonic brains. The 3D reconstructions were found ideal for understanding the temporal changes occurring in embryonic brains subjected to defined maternal heat stresses. The method involved 4 X 4 matrices using homogenous coordinate theory, being the most ideal and allowing a constant mechanism for all transformations. Total time from examination of sections to obtaining an accurate printed 3D reconstruction is approximately 1 h if 22 sections are used.

Animals↗
PubMed1986

Hyperthermia as a teratogen: a review of experimental studies and their clinical significance.

Although hyperthermia is teratogenic in birds, all the common laboratory animals, farm animals, and primates and satisfies defined criteria as a teratogen, its study as a human teratogen has been neglected. Homeothermic animals, including humans, can experience body temperature elevations induced by febrile infections, heavy exercise and hot environments which exceed the thresholds (1.5-2.5 degrees C elevation) which are known to cause a syndrome of embryonic resorptions, abortions, and malformations in experimental animals. Hyperthermia is particularly damaging to the central nervous system, and if a threshold exposure occurs at the appropriate stages of embryonic development, exencephaly, anencephaly, encephalocoele, micrencephaly, microphthalmia, neurogenic talipes, and arthrogryposis can be produced in a high proportion of exposed embryos, the incidence and type of defect depending on the species and strain within species, the stage of development, and the severity of hyperthermic exposure. Other defects which can be induced experimentally include exomphalos, hypoplasia of toes and teeth, renal agenesis, vertebral anomalies, maxillary hypoplasia, facial clefting, cataract, coloboma, and heart and vascular defects. Proliferating cells are particularly sensitive to temperature elevations, resulting in arrest of mitotic activity and immediate death of cells in mitosis with threshold elevations (1.5-2.5 degrees C) and delayed death of cells probably in S phase with higher elevations (3.5 degrees C). In general, lower temperature elevations (2.5 degrees C) require longer durations of elevation to cause defects than a simple spike at a higher elevation (4.5 degrees C). The death of cells is largely confined to the brain and in the day 21 guinea pig embryo to the alar regions of the brain. Cell death probably accounts for most of the defects in the central nervous system, but microvascular disturbances leading to leakage, oedema and haemorrhage, placental necrosis, and infarction are other known effects of hyperthermia; and these are probably involved in the pathogenesis of many defects of the heart, limbs, kidneys, and body wall. Recent experiments have demonstrated protection of rat embryos in culture against a known teratogenic exposure by a brief nonteratogenic exposure given at least 15 min earlier. This protection is associated with the synthesis of heat-shock proteins, and temporary arrest of the cell proliferative cycle. Hyperthermia appears to be capable of causing congenital defects in all species and may act alone or synergistically with other agents.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Toxicity and DNA damage induced by 1-nitropyrene and its derivatives in Chinese hamster lung fibroblasts.

1-Nitropyrene and its chemically synthesised derivatives were investigated for their cytotoxicity and ability to induce DNA-strand breaks in Chinese hamster lung fibroblasts. Both 1-nitrosopyrene (0.25-60 micrograms/ml) and 1-aminopyrene (0.25-25 micrograms/ml) were cytotoxic, and induced the formation of DNA lesions, which were measured as DNA single-strand breaks after sedimentation in alkaline sucrose-density gradients. Higher doses of 1-aminopyrene (25-60 micrograms/ml) inhibited the formation of DNA single-strand breaks. 1-Nitropyrene was not toxic (0.25-60 micrograms/ml) and induced low levels of detectable DNA strand breaks, whilst N-acetyl-1-aminopyrene was inactive. The post-mitochondrial supernatant fraction of Aroclor-induced rat-liver containing 4 mM NADPH (S9 mix) did not promote the activation of 1-nitropyrene. In fact DNA strand breaks induced by either 1-nitropyrene or 1-nitrosopyrene was abolished in the presence of S9 mix. The 1-nitropyrene reduced intermediate, N-hydroxy-1-aminopyrene was synthesised by the reduction of 1-nitrosopyrene with ascorbic acid. In the presence of ascorbic acid, 1-nitrosopyrene caused a 5-fold increase in the number of DNA single-strand breaks when compared to cells treated with 1-nitrosopyrene alone. The results are discussed in terms of the metabolic activation of 1-nitropyrene and 1-aminopyrene in Chinese hamster lung cells.

Animals↗
PubMed1986

The induction of DNA adducts in mammalian cells exposed to 1-nitropyrene and its nitro-reduced derivatives.

1-Nitropyrene, 1-nitrosopyrene and 1-aminopyrene were investigated for their ability to induce covalently bound DNA adducts in calf thymus DNA and Chinese hamster lung fibroblasts. Xanthine oxidase catalysed the induction of one major and one minor DNA adduct in 1-nitropyrene- or 1-nitrosopyrene-treated calf thymus DNA, whilst 1-aminopyrene was inactive. These compounds did not form detectable DNA adducts in the absence of xanthine oxidase. The major DNA adduct produced by 1-nitropyrene and 1-nitrosopyrene in calf thymus DNA co-migrated on h.p.l.c., and the structure was consistent with that previously described by others as N-(deoxyguanosin-8-yl)-1-aminopyrene. The compounds were investigated for their ability to form DNA adducts in Chinese hamster lung fibroblasts. 1-Nitropyrene (5.2 pmol/mg DNA/h) and 1-nitrosopyrene (129 pmol/mg DNA/h) formed a single DNA adduct in Chinese hamster lung cells which co-eluted on h.p.l.c. with the C-8 deoxyguanosine adduct isolated from 1-nitropyrene-treated calf thymus DNA. 1-Nitrosopyrene was the most efficient compound investigated for the production of the C-8 guanine adducts. In contrast, 1-aminopyrene (14.7 pmol/mg DNA/h) induced the formation of a DNA adduct which did not co-elute with the C-8 guanine adduct. The data presented here suggest that 1-nitropyrene and 1-aminopyrene are metabolized to reactive intermediates which form different DNA adducts in Chinese hamster lung fibroblasts.

Animals↗
PubMed1985

The induction of microphthalmia, encephalocele, and other head defects following hyperthermia during the gastrulation process in the rat.

The aim of this study was to ascertain whether there is a period during early embryonic development of the rat that is particularly sensitive to hyperthermia. Pregnant Sprague-Dawley rats were partially immersed in a water bath at 43.5 degrees C until their core temperatures, monitored by a rectal thermistor probe, were elevated to 43.5 degrees C. The procedure was repeated 6 hours later. The regimen of two heatings was performed over a range of development from early gastrulation (8 days 18 hours) to about the 12 somite stage (10 days 18 hours). The rats were killed on days 17-19 and the fetuses were examined. Each group contained a minimum of five litters. The main teratogenic effect of the hyperthermia was the induction of one or more head defects, notably microphthalmia, encephalocele (either a single, large, parietal encephalocele or multiple small protuberances), and maxillary hypoplasia. Microphthalmia was the most common defect with approximately 90% of surviving fetuses having small eyes when heating occurred between 9 days 6 hours and 10 days 0 hours (9.06 and 10.00). Encephaloceles were induced by heating between 9.00 and 10.00 with a peak sensitivity between 9.12 and 9.18 when 57% of surviving fetuses were affected. Maxillary hypoplasia resulted from heating between 9.06 and 10.06 with up to 20% of surviving fetuses being affected. Control rats were exposed to the same experimental procedure in a water bath at 38 degrees C on 9.12 and 9.18, the gestational time most sensitive to hyperthermia induced malformations. There were no abnormal fetuses in the controls. The critical period identified spans 9 days 6 hours to 10 days 0 hours gestational age. In developmental terms this includes a large proportion of the gastrulation process.

Animals↗
PubMed1985

Hyperthermia as a teratogen: parameters determining hyperthermia-induced head defects in the rat.

This study determined the relationship between the duration and extent of temperature elevation, during a critical period of rat embryonic development, and the induction of congenital malformations. Pregnant Sprague-Dawley rats, at 9 days 12 hours gestation (gastrulation stage), were partially immersed in a water bath until their core temperature, monitored by a rectal thermistor probe, was elevated to a nominated temperature. Seven temperatures were tested from 40.5 degrees C to 43.5 degrees C, elevations of 2.0-5.0 degrees C in core temperature. Various durations at each of these temperatures were tested for potential teratogenicity. A single elevation of 5.0 degrees C or 4.5 degrees C needed only a "spike" in duration to be teratogenic, 4.0 degrees C was teratogenic within 5 minutes, 3.5 degrees C within 10 minutes, 3.0 degrees C within 20 minutes, and 2.5 degrees C within 1 hour. An elevation of 2.0 degrees C for 8 hours was not teratogenic. Microphthalmia was the most common malformation at all teratogenic temperatures and was frequently the only malformation seen at the shortest time exposure for a particular temperature. Encephalocele, facial clefting, and maxillary hypoplasia were the other frequently seen malformations. Five control rats were placed in the water bath for 2 hours at 38 degrees C so that their core temperature was not elevated. All the control fetuses were normal. An elevation of 2.5 degrees C for 1 hour was the threshold combination for teratogenesis. As the temperature increased above a 2.5 degrees C elevation the necessary duration of exposure for teratogenesis decreased.

Animals↗
PubMed1985

Effects of hyperthermia on the myelograms of adult and fetal guinea-pigs.

The myelograms of adult guinea-pigs at various stages after brief exposure to hyperthermia were compared with those of control animals. The proportions of neutrophil and eosinophil metamyelocytes and of intermediate normoblasts were significantly reduced for at least 24 h after exposure and the proportions of neutrophil polymorphs and lobulated eosinophils were significantly increased over this period. The mitotic index was reduced for up to 5 h. Morphological changes in cells included hypersegmentation of nuclei, pyknosis, necrobiotic changes, development of pseudopodia, and abnormalities of mitosis. The myelograms of newborn guinea-pigs which had been heated on days 20-23 of pregnancy showed no significant changes.

Animals↗
PubMed1984

Retardation of brain growth of guinea pigs by hyperthermia: effect of varying intervals between successive exposures.

Guinea pigs were exposed to a temperature of 42.5-43.5 degrees C on three occasions between days 20 and 23 of pregnancy. In the first experiment, groups of mothers were exposed at intervals of 18-30 hr. Each exposure ended when the deep rectal temperature had been over 43 degrees C for 6 min and mean temperatures were 43.2-43.4 degrees C. Micrencephaly was found in 78% of heated newborn offspring, the mean brain weights of all groups being significantly less than controls. In the heated groups, the brain weights were reduced significantly as the interval between exposures decreased. Abnormalities other than micrencephaly were found in 10% of heated offspring and included exomphalos, clubfoot, and hypodactyly. In the second experiment, groups of mothers were exposed for 1 hour at intervals of 6-20 hr. The mean temperatures of heated groups were 42.6-42.9 degrees C. The mean brain weights of all groups of heated newborn were significantly reduced and micrencephaly was found in 61% of newborn. Brain weights were reduced significantly as mean maternal temperature increased. There was a significant interaction between the level of temperature elevation and the interval between exposures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Hyperthermia and the induction of neural tube defects in mice.

The aim of this study was to examine some parameters determining the teratogenicity of hyperthermia. Pregnant inbred (C57B1/6J and CBA/Ca/T6) and outbred (QS) mice were partially immersed in a water bath at 43-43.5 degrees C until their core temperature, monitored by a rectal thermister probe, was elevated to 43 degrees C for the inbred mice and 43.5 degrees C for the outbred mice. The procedure was repeated 6 h later. The regimen of 2 heatings was performed over a range of development from pregastrulation to about the 24 somite stage. The mice were killed on day 19, and the fetuses were examined. Exencephaly was the common malformation seen in each strain. It occurred at a maximum incidence of 34% in the QS mice, 14% in the CBA strain, and 20% in C57B1 mice. For the CBA and QS mice 4 to 11-15 somites was the most heat sensitive stage of development for the induction of exencephaly while in the C57B1 mice the preceding 24 hr of development were most sensitive. Control mice were exposed to the same experimental procedure in a water bath at body temperature at the most sensitive stage of development for the strain. There were no instances of exencephaly in the controls. The sex of all fetuses was determined and revealed a high female/male ratio among the fetuses with exencephaly (2.1 for the QS mice, 1.7 for the CBA mice, and 3.1 for the C57B1 mice) compared with a ratio of approximately 1.0 for all fetuses. Analysis in the QS mice indicated that the predominance of female exencephalics was probably due to prenatal loss of male embryos.

Abnormalities, Multiple↗
PubMed1984

Effects of lead and hyperthermia on prenatal brain growth of guinea pigs.

The effects of lead at blood levels of 100 micrograms/100ml or less on the brains of young animals have not been clearly defined, and little is known of its effects and interactions with other agents on prenatal brain development. This study examined the effects of subclinical doses of lead acetate given to pregnant guinea pigs on the development of the embryo brain. At 9 A.M. on day 20 or 21 of pregnancy, guinea pigs were given 6, 12.5, or 25 mg/kg body weight of 0.5% lead acetate in distilled water by intraperitoneal injection. Some of the animals at each dose rate were also exposed to hyperthermia at 11 A.M. on the day of injection and the following day. Another group was exposed to hyperthermia without lead treatment. A saline-treated control group was used for comparison. Mean levels of lead in blood 1 hour after dosing ranged between 65 and 128 micrograms/100 ml and at 24 and 72 hours between 65 and 96 micrograms/100 ml. Brain weights of newborn guinea pigs in the 12.5- and 25-mg lead acetate group were significantly reduced compared with control values. Body weights of all groups receiving lead were not significantly different from those of controls. There was no indication of interaction between hyperthermia and lead acetate in doses of 6 or 12.5 mg/kg. At 25 mg/kg plus hyperthermia, there appeared to be a strong synergistic response, with an incidence of 88% micrencephaly compared with 5% in the group given 25 mg/kg without hyperthermia and 46% in the hyperthermia without lead group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗