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Biomedical subjects

L E Morris

Publications and source records attributed to L E Morris.

At least 19 recordsLinked to original sources
PubMed1994

Closed carbon dioxide filtration revisited.

There are compelling reasons why the closed carbon dioxide filtration method for inhalation anaesthesia deserves serious reconsideration. Use of the closed absorption system today can provide all the benefits recognised by those who introduced it seventy to eighty years ago. A most important benefit is the increased opportunity of learning afforded the user, which leads either neophyte or senior clinician to improvement of both concept and clinical skills. The current resurgence of interest is fully appropriate for all physicians who aspire to be true specialists in the care of patients during clinical anaesthesia.

Absorption↗
PubMed1994

Closed system with agent-specific vaporizers and nitrous oxide.

Through judicious use of nitrous oxide the closed system can be quite effectively used with currently available equipment including both agent-specific direct-reading percentage vaporizers and suitable devices for the measurement of end-tidal concentrations of oxygen, carbon dioxide and anaesthetic agents. It is only necessary to think in terms of required volumes of fresh gases and vapours added to the system as well as the appropriate concentrations of oxygen and anaesthetic in the respired mixture. When used as described the inspired concentration of nitrous oxide in the closed system should never exceed 50% (usually about 40%). Therefore nitrous oxide will not pose the threat of hypoxaemia unless misused. Experience in teaching this method during the previous decade supports a belief that learning the use of a truly closed circle absorption anaesthesia system is fundamentally important to the development of clinical skills and also facilitates understanding of basic concepts related to respiratory physiology and the uptake and distribution of inhalation anaesthetics. It follows that students and residents should be introduced to this method in the early weeks of their learning experience.

Adsorption↗
PubMed1994

Salvage therapy in epithelial ovarian cancer.

Table 1 summarizes studies in which clinical or pathologic response rates can be determined. The majority of patients in these studies had macroscopic drug-resistant tumors, and most had received cisplatin-based chemotherapy. It is noteworthy that the response rate in this group of patients is considerably higher than the 30% to 36% seen with the most active salvage therapies, such as taxol (paclitaxel). Like most trials of salvage chemotherapy for refractory ovarian carcinoma, many responses were short-lived. Toxicity in these studies is comparable to that seen in trials of ASCT in other solid tumors. The promising results observed in these small studies of ASCT in ovarian carcinoma warrant further investigation focused on defining which groups of patients are likely to benefit from this approach. Based on evidence from the lymphohematopoietic malignancies, it would seem reasonable to use ASCT in patients early in the course of their disease before extensive pretreatment and preferably at a time of minimal tumor burden. Some groups have been exploring ASCT as consolidation therapy after surgery and limited debulking chemotherapy. Based on kinetic models of tumor growth, other investigators have suggested that multiple courses of high-dose chemotherapy with ASCT after debulking surgery may result in more cures than a single ASCT after conventional chemotherapy. The feasibility of performing sequential ASCT has been well documented. So far the best drug regimens, the number of cycles that should be used, and the patients who should be candidates for high-dose chemotherapy and ASCT remain undefined. Presently, there is no role for this therapeutic modality outside of well-designed clinical trials.

Antineoplastic Agents↗
PubMed1993

Prevention and management of graft-versus-host disease. Practical recommendations.

Graft-versus-host disease (GVHD) is the leading cause of failure of allogeneic bone marrow transplantation. The disease typically involves the skin, liver and gastrointestinal tract, with death frequently resulting from infectious complications. Cyclosporin-based drug combinations are the mainstay of GVHD prophylaxis. The major toxicity of cyclosporin is renal dysfunction, and optimal strategies of therapeutic drug monitoring to minimise toxicity and maximise clinical efficacy have yet to be devised. Initial treatment of established GVHD usually includes high dose corticosteroids. Patients failing to respond to first line therapy have a poor prognosis. Investigational approaches to decreasing the mortality associated with GVHD include using monoclonal antibodies directed at specific T cell subsets, and T cell depletion of bone marrow grafts.

Bone Marrow Transplantation↗
PubMed1992

Autologous graft-versus-host disease: a novel approach for antitumor immunotherapy.

Autologous bone marrow transplantation (BMT) is a therapeutic option for the treatment of lymphohematopoietic malignancies and solid tumors. Despite the intensive cytoreductive therapy, however, the rates of tumor recurrence after autologous BMT remain unacceptably high. Current studies suggest that the administration of cyclosporine (CsA) disrupts the reconstitution of self-tolerance following autologous BMT leading to the induction of an autoimmune graft-versus-host disease (GVHD). Studies in a rat tumor model and preliminary clinical trials suggest that this autoimmune or autologous GVHD provides a significant antitumor effect. Moreover, the antitumor effect of autologous GVHD can be enhanced by administration of gamma-interferon, which upregulates the antigen recognized by the autoreactive effector cells of autologous GVHD. These studies indicate that the induction of an autoimmune GVHD after autologous BMT may be a promising immunotherapeutic approach for treatment of certain neoplastic diseases.

Animals↗
PubMed1989

Protective value of a liver initiation-promotion regimen against the lethal effect of carbon tetrachloride in rats.

This study was designed as one test of the hypothesis that an early sequence of steps in hepatocarcinogenesis in the rat, with the production of hepatocyte nodules, may be a special form of adaptive response that has survival value for the host. Fischer 344 rats were initiated with a single dose of diethylnitrosamine. Hepatocyte nodules were rapidly generated by selecting for resistant hepatocytes by a brief exposure to 2-acetylaminofluorene coupled with partial hepatectomy, a procedure that leads to liver cancer without any further treatment. Most animals with hepatocyte nodules were completely resistant to single doses of CCl4 that induced 100% mortality in control animals. The demonstration of this protective effect is consistent with the proposed hypothesis.

Animals↗
PubMed1988

Double-blind comparison of butorphanol and morphine in patient-controlled analgesia.

In this study, the patient-controlled analgesia (PCA) technique was used to compare the suitability of butorphanol with that of morphine in relieving postoperative pain. Twelve patients, 19-77 years old, who had abdominal surgery, used the PCA device through the first 24-hour postoperative period. Results showed that all patients expressed satisfaction with the PCA technique. Analysis of the degree of discomfort according to the verbal description scale, recordings of respiratory rate, and assessment of sedation status showed no significant differences between patients who received butorphanol and those who received morphine. Patients were able to maintain acceptable analgesia with minimal sedation. There were no adverse side effects reported with butorphanol.

Adult↗
PubMed1988

Busulfan-induced hepatitis.

A 61-yr-old man with chronic myelocytic leukemia treated continuously for 8 yr with busulfan presented with fever, abdominal pain, and elevated liver enzymes in a cholestatic pattern. Evaluation of his liver and biliary tract with ultrasound and computerized tomography disclosed no structural abnormality. A percutaneous needle liver biopsy revealed cellular cholestasis with focal liver cell necrosis accompanied by a mild inflammatory infiltrate. Busulfan was discontinued, with subsequent normalization of liver enzymes and resolution of fever. These findings are interpreted as being compatible with busulfan-induced hepatitis.

Busulfan↗
PubMed1984

Inspired humidity in anaesthesia breathing circuits: comparison and examination of effect of Revell circulator.

Humidity levels of respired gases in spontaneously breathing patients were measured with a quadrupole mass spectrometer (Medishield Model MS-2) and compared between various anaesthetic systems during clinical anaesthesia. In studies of high flow rebreathing non-absorption systems the mean inspired absolute humidity averaged approximately 16 mg X l-1 (range 14.7 to 16.1 mg X l-1) compared to a semiclosed circle absorption system (BOC MK III) in which values for absolute humidity varied from 6.8 +/- 5.1 mg X l-1 for children through 9.5 +/- 3.0 mg X l-1 for adults), and the closed circle absorption system in which values of 20.5 +/- 2.3 mg X l-1 were only gradually reached. Addition of a functioning Revell circulator to the circle absorption system provided immediately markedly higher levels of inspired humidity during clinical use, either semiclosed (15.4 +/- 5.1 mg X l-1 in children to 18.8 +/- 2.4 mg X l-1 in adults), or closed (23.3 +/- 1.8 mg X l-1 in adults). These markedly higher inspired levels of absolute humidity were attained during forced circulation of respired gas provided by the Revell circulator without the concomitant disadvantages of rebreathing or the potential hazards associated with some humidifying devices.

Adult↗
PubMed1982

Risk factors for breast cancer in women in northern Alberta, Canada, as related to age at diagnosis.

A population-based case-control study involving interviews with 577 female breast cancer patients and 826 controls in northern Alberta. Canada, revealed that some determinants of breast cancer varied according to age. Among women under age 45, risk factors included a younger age at menarche, late age at last birth, high parity, and recent use of oral contraceptives. At older ages risk was related to natural as opposed to surgical menopause, late age at first birth, low parity, late age at natural menopause, and tonsillectomy. At all ages there was an increased risk of breast cancer associated with difficulty in conceiving, benign breast disease, not having breast fed, and a history of breast cancer among mothers or sisters. For some variables the age differences were pronounced; the combination of low parity and late age at first birth was associated with a sevenfold increase in breast cancer risk at risk at ages 55-80 but a slight decrease at ages under 45. The effect of tonsillectomy steadily increased with age and represents a new lead, but certain features of the data suggest that the link to oral contraceptives among among younger women and the inverse relation to breast feeding at all ages may not be causal. Even though design limitations (cases interviewed in a different setting from controls) appeared not to influence conclusions, the results may have been subjected to interview bias and thus should be interpreted cautiously.

Adult↗
PubMed1981

Esophageal cancer among black men in Washington, D.C. I. Alcohol, tobacco, and other risk factors.

A case-control study involving interviews with the next of kin or close friends of 120 black males who recently died of esophageal cancer and 250 similarly aged black males who died of other causes was undertaken to discover reasons for the exceptionally high mortality from this cancer in Washington, D.C. The age-adjusted annual death rate in Washington, D.C., for nonwhite males, 1970-75, was 28.6/100,000, far higher than the national rate of 12.4/100,000 and the rates in other metropolitan areas of the country. The major factor responsible for the excess was alcoholic beverage consumption, with an estimated 81% of the esophageal cancers attributed to its use; high use of alcoholic beverages was also found among the controls. The relative risk (RR) of esophageal cancer associated with use of alcoholic beverages was 6.4 (95% confidence interval=2.5, 16.4). The RR increased with amount of ethanol consumed and was highest among drinkers of hard liquor, although the risk was also elevated among consumers of wine and/or beer only. The RR associated with cigarette smoking was 1.9 (1.0, 3.5) when controls with smoking-related causes of death were excluded but declined to 1.5 (0.7, 3.0) when adjusted for ethanol consumption. Significant differences of approximately twofold were found between low and high levels of a) consumption of fresh or frozen meat and fish, fruits and vegetables, and dairy products and eggs and b) relative weight (wt/ht2). The inverse trends with these general measures of nutritional status were not explained by alcoholic beverage consumption or socioeconomic status as measured by educational level.

Adult↗