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Biomedical subjects

A Baker

Publications and source records attributed to A Baker.

At least 19 recordsLinked to original sources
PubMed1992

Liver transplantation for fulminant hepatic failure and late-onset hepatic failure in children.

The mortality rate of fulminant hepatic failure (FHF) and late-onset hepatic failure (LOHF) in childhood has remained between 70 and 95 per cent despite recent improvements in medical therapy. Liver transplantation has become an important therapeutic option in adults with this condition but has been performed infrequently in children. Between March 1988 and August 1991, 12 children aged between 1 month and 14 years with FHF or LOHF received 13 liver transplants. The aetiology was viral hepatitis in eight children (non-A non-B in six, A in two), drug hepatotoxicity (carbamazepine) in two, autoimmune hepatitis in one and congenital haemochromatosis in one. Reduced-size livers were used for ten of the 13 transplants. Morbidity after operation included infective complications and abdominal bleeding. Two patients died from graft versus host disease, one from brain aspergillosis and another from graft infarction after portal vein thrombosis. Eight patients survive after a median follow-up of 18 months. Liver transplantation should be the therapeutic choice for children with FHF and LOHF for whom the chances of recovery are poor.

Adolescent↗
PubMed1992

MAO inhibitors and coronary artery surgery: a patient death.

The mechanisms of action of monoamine oxidase inhibitors (MAOIs) suggest that patients taking them may respond with hyper- or hypotension when undergoing coronary artery surgery. We describe a case where MAOIs were present and fentanyl and midazolam were the anaesthetic agents used. The anaesthesia and surgery were performed without incident. Postoperative ICU care was complicated by hypertension, hyperthermia, and severe shivering followed by hypotension resistant to therapy and finally death. Diagnoses of pulmonary embolism and sepsis were unproven and may have played a role. The MAOIs may also have played a role. Reactions in patients while taking both meperidine and MAOIs are unusual and animals react differently from humans to a combination of MAOIs and narcotics. There are only five reported cases where fentanyl was given to patients on MAOIs. We conclude that, until there is more information, MAOIs should be discontinued, if possible, before surgery in which catecholamines may be needed.

Acidosis↗
PubMed1992

Drug use and HIV risk-taking behaviour among clients in methadone maintenance treatment.

Current drug use and HIV risk-taking behaviour of a sample of 95 methadone maintenance clients was investigated. Subjects had been on their current programme for an average of 70.9 weeks with a mean daily dose of methadone of 65.6 mg. Two-thirds had injected heroin, and 82% had injected a street drug in the month prior to interview. Over 20% of subjects had shared a needle in the month before interview, all with only one other person. Subjects who had injected cocaine in the month before interview had significantly higher levels of injecting risk-taking behaviour than those subjects who had injected but not used cocaine. Condom use among subjects was low, particularly in regular relationships. While knowledge concerning HIV was high among subjects, there was no relation between level of knowledge and actual behaviour. It is concluded that knowledge alone is not sufficient to ensure behaviour change.

Adolescent↗
PubMed1992

Phoretic and parasitic mites infesting the New World screwworm fly, Cochliomyia hominivorax, following sterile insect releases in Libya.

During the screwworm eradication programme in Libya in 1991, trapped specimens of Cochliomyia hominivorax (Coquerel) were found infested with phoretic mites, Macrocheles muscaedomesticae (Scopoli), or parasitic mites, Trichotromidium muscarum (Riley). The possible sources of infestation and potential effects of mites on screwworm flies are discussed.

Animals↗
PubMed1992

Quenching of singlet oxygen by biomolecules from L1210 leukemia cells.

Singlet oxygen lifetimes for detergent-dispersed L1210 leukemia cells in deuterium oxide buffer were measured by following the decay of 1270 nm phosphorescence. Four photosensitizers and two detergents were studied. Stern-Volmer plots were linear over the cell concentration range studied (0-10(7) cells/mL). The singlet-oxygen quenching constants obtained depended somewhat upon the specific combination of detergent and photosensitizer used. Extrapolation of the singlet-oxygen lifetime data to "100%" cell concentration (1.39 +/- 0.04 x 10(9) cells/mL) and correction for the contribution of the water solvent gave a singlet-oxygen lifetime between 0.17 and 0.32 microseconds for the L1210 leukemia cell. The theoretical contributions of various types of biological molecules within the L1210 cell to the total singlet-oxygen quenching were calculated from their concentrations and their quenching constants. These calculations suggest that proteins will quench most of the singlet-oxygen. Only about 7% of the singlet-oxygen is quenched by water.

Animals↗
PubMed1992

Typical absence seizures in adults: clinical, EEG, video-EEG findings and diagnostic/syndromic considerations.

Eighteen women and five men had typical absences. These included 10% of a consecutive hospital series of 200 adult patients with epileptic disorders. The absences began between the ages of seven and 46 years and varied in type and severity. Twenty patients also had generalised tonic-clonic seizures, ranging in frequency from one in a lifetime to one per month. Myoclonic jerks of the limbs occurred in 11 patients but were not associated with the absence attacks. Eyelid myoclonus consistently occurred with absence attacks in four patients and perioral myoclonus in two patients. Absence status occurred in five patients. Absence seizures were frequently unrecognised or misdiagnosed as complex partial seizures. Satisfactory control was achieved with sodium valproate. Electroencephalography, particularly video-electroencephalography, was invaluable in the diagnosis, but focal abnormalities in seven patients might have been erroneously interpreted as indicating partial seizures. This series showed that clinical and EEG manifestations are often syndrome-related and that there are more epileptic syndromes with typical absences than those presently recognised.

Adult↗
PubMed1992

Successful delivery of twins in a woman with a unicornuate uterus.

The presence of a unicornuate uterus is a rare congenital condition which represents only 1-2% of uterovaginal anomalies. Previous reports have demonstrated an increase in the number of cases of primary infertility, pregnancy loss and preterm labor associated with the unicornuate uterus. Herein, we present a case in which a patient conceived following a thawed frozen embryo transfer. She had been given the option of selective reduction, because of the high risk associated with this pregnancy, but refused and her pregnancy successfully continued to 35 weeks and delivery of twins.

Adult↗
PubMed1992

Phagocytosis of apoptotic neutrophils does not induce macrophage release of thromboxane B2.

Senescent human neutrophils undergo programmed cell death (apoptosis), leading to their recognition and phagocytosis by mature macrophages. At inflamed sites in vivo these processes may represent a neutrophil removal mechanism with the potential to limit the histotoxic capacity of these cells. Phagocytosis can provoke marked proinflammatory responses by macrophages. A macrophage proinflammatory response to the ingestion of apoptotic neutrophils would limit the efficacy of this neutrophil removal mechanism as a component of inflammatory resolution. In the present study we examined two macrophage proinflammatory responses; secretion of the granule enzyme N-acetyl-beta-D-glucosaminidase (NAG) and release of the membrane lipid-derived inflammatory mediator thromboxane A2 (TxA2, measured as TxB2). By contrast with the marked release of NAG and TxB2 elicited by phagocytosis of control particles (opsonised zymosan and immunoglobulin G-coated erythrocytes), macrophage ingestion of apoptotic neutrophils resulted in minimal release of NAG and no release of TxB2; indeed, there was a small depression of TxB2 release that was not due to a toxic effect of neutrophil uptake because macrophages ingesting apoptotic neutrophils retained marked TxB2 responses to subsequent stimulation with opsonised zymosan. Furthermore, there was significant TxB2 release in response to macrophage phagocytosis of apoptotic neutrophils that had been coated with opsonic serum, demonstrating that the lack of macrophage response was determined by the mechanism of recognition rather than the properties of the apoptotic particle itself. These observations are consistent with the hypothesis that macrophage clearance of senscent neutrophils undergoing apoptosis is an injury-limiting mechanism that favors resolution rather than persistence of the inflammatory response and are consistent with observations that the waves of apoptotic cell removal seen in embryological removal and thymic involution do not trigger an inflammatory response.

Acetylglucosaminidase↗
PubMed1991

Mortality and morbidity in patients receiving encainide, flecainide, or placebo. The Cardiac Arrhythmia Suppression Trial.

BACKGROUND AND METHODS: In the Cardiac Arrhythmia Suppression Trial, designed to test the hypothesis that suppression of ventricular ectopy after a myocardial infarction reduces the incidence of sudden death, patients in whom ventricular ectopy could be suppressed with encainide, flecainide, or moricizine were randomly assigned to receive either active drug or placebo. The use of encainide and flecainide was discontinued because of excess mortality. We examined the mortality and morbidity after randomization to encainide or flecainide or their respective placebo. RESULTS: Of 1498 patients, 857 were assigned to receive encainide or its placebo (432 to active drug and 425 to placebo) and 641 were assigned to receive flecainide or its placebo (323 to active drug and 318 to placebo). After a mean follow-up of 10 months, 89 patients had died: 59 of arrhythmia (43 receiving drug vs. 16 receiving placebo; P = 0.0004), 22 of nonarrhythmic cardiac causes (17 receiving drug vs. 5 receiving placebo; P = 0.01), and 8 of noncardiac causes (3 receiving drug vs. 5 receiving placebo). Almost all cardiac deaths not due to arrhythmia were attributed to acute myocardial infarction with shock (11 patients receiving drug and 3 receiving placebo) or to chronic congestive heart failure (4 receiving drug and 2 receiving placebo). There were no differences between the patients receiving active drug and those receiving placebo in the incidence of nonlethal disqualifying ventricular tachycardia, proarrhythmia, syncope, need for a permanent pacemaker, congestive heart failure, recurrent myocardial infarction, angina, or need for coronary-artery bypass grafting or angioplasty. CONCLUSIONS: There was an excess of deaths due to arrhythmia and deaths due to shock after acute recurrent myocardial infarction in patients treated with encainide or flecainide. Nonlethal events, however, were equally distributed between the active-drug and placebo groups. The mechanisms underlying the excess mortality during treatment with encainide or flecainide remain unknown.

Actuarial Analysis↗
PubMed1991

Direct observation of singlet oxygen phosphorescence at 1270 nm from L1210 leukemia cells exposed to polyporphyrin and light.

Near-infrared emission (1170-1475 nm) was studied from L1210 leukemia cells incubated with polyporphyrin (fractionated hematoporphyrin derivative), suspended in deuterium oxide buffer, and then exposed to light. Following pulsed laser excitation, the near-infrared emission decayed in two phases. The first phase of the emission (0-2 microseconds) was principally due to polyporphyrin fluorescence. The second phase of the emission (20-90 microseconds) was due mainly to singlet oxygen. Evidence supporting the assignment of the second phase emission to singlet oxygen included a spectral analysis showing a peak near 1270 nm and reductions in the second phase emission caused by the singlet oxygen quenchers, histidine, carnosine, and water. The second phase emission decayed in a biexponential manner with lifetimes of 4.5 +/- 0.5 and 49 +/- 4 microseconds. Most of the singlet oxygen in the second phase emission was likely due to singlet oxygen that was generated near the surface of the L1210 leukemia cells and then diffused into the deuterium oxide buffer. Direct measurements of singlet oxygen phosphorescence at 1270 nm may prove to be a useful analytical technique for studying photochemical generation of singlet oxygen in cultured cells.

Animals↗
PubMed1991

Rapid cervical cytology screening.

2030 Papanicolaou-stained cervical smears were submitted for rapid screening prior to routine screening; 30 seconds were allowed for each slide, and those thought to be abnormal were identified. The results were compared with those of conventional screening. All severe and moderately dyskaryotic cases were detected by the rapid technique, as were the majority of mild dyskaryosis and borderline cases. When a laboratory has a backlog it may be worth rapid-screening all slides in addition to routine screening, so that patients most at risk can receive prompt treatment.

Cytodiagnosis↗
PubMed1991

Changing pattern of pulmonary metastases with adjuvant chemotherapy in patients with osteosarcoma: results from the multiinstitutional osteosarcoma study.

The multiinstitutional osteosarcoma study (MIOS), a randomized trial of adjuvant therapy for osteosarcoma with a concurrent control group, registered 113 patients from June 1982 to August 1984. Preliminary analysis of the study indicated a significant event-free survival advantage favoring immediate adjuvant chemotherapy, (P less than .001). For patients treated with surgery alone or with surgery and adjuvant chemotherapy, the lungs were involved in more than 80% of the relapses. Patients relapsing after surgery alone tended to relapse earlier (P less than .01), had more pulmonary nodules (P less than .01), and had more frequent bilateral pulmonary involvement (P less than .01) than those treated with immediate postsurgical adjuvant chemotherapy. However, patients relapsing after treatment with surgery alone experienced a significantly longer interval to further disease progression (P less than .01) and improved survival after relapse (P = .01) when compared with patients who relapsed after treatment with immediate adjuvant chemotherapy. The only factor predictive of survival after relapse was if the patient could be made surgically disease-free after initial relapse (P = .03).

Antineoplastic Agents↗
PubMed1991

Adjuvant chemotherapy of high-grade osteosarcoma of the extremity. Updated results of the Multi-Institutional Osteosarcoma Study.

The Multi-Institutional Osteosarcoma Study (MIOS) was designed to determine whether intensive multiagent adjuvant chemotherapy improves the outcome of patients with nonmetastatic high-grade osteosarcoma of the extremity as compared with concurrent controls. After definitive surgery of the primary tumor, patients were randomly assigned to immediate adjuvant chemotherapy or to observation without adjuvant treatment. Updated results of this trial indicate that the projected six-year event-free survival for the control group is 11% compared to 61% for the chemotherapy group (p less than 0.001). Similar results were observed in patients who declined randomization but who were followed according to the treatment arms of the protocol. When randomized and nonrandomized patients are pooled according to assigned treatment, a survival advantage favoring those patients treated with immediate adjuvant chemotherapy is apparent. An analysis of prognostic factors among patients receiving immediate adjuvant chemotherapy reveals that elevation of the serum lactic dehydrogenase at diagnosis is the factor most predictive of adverse outcome. Location of the primary site in the tibia confers a favorable prognosis. The authors conclude that the natural history of high-grade osteosarcoma of the extremity has not changed over the past two decades. The administration of immediate adjuvant chemotherapy has a significant favorable impact on event-free survival and should be recommended for all such patients.

Adult↗