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Biomedical subjects

J McKenzie

Publications and source records attributed to J McKenzie.

At least 37 records · Page 2Linked to original sources
PubMed1997

Vagal control of left ventricular contractility is selectively mediated by a cranioventricular intracardiac ganglion in the cat.

Activation of the vagus nerve leads to decreases in sinoatrial (SA) rate, atrioventricular (AV) conduction, and myocardial contractility. Previous data are consistent with the hypothesis that vagal control of cardiac rate and AV conduction are mediated by two anatomically separated and physiologically independent parasympathetic intracardiac ganglia located in fat pads on the surface of the right and left atria, respectively. These data suggested that vagal control of ventricular contractility might be mediated through another intracardiac ganglion. We examined the ventricles of cat hearts histologically for the presence of ganglia. Multiple small basophilic ganglia composed of a few neurons, and an occasional larger ganglion were found embedded in the epicardial fat surrounding the cranial margin of the anterior surface of the left ventricle, near the juncture with the right ventricle, which we refer to as the CV ganglion. In anesthetized cats, right cervical vagal stimulation decreased SA rate by 44 +/- 5%, decreased the rate of AV conduction by 68 +/- 14%, and reduced ventricular contractility by 19.5 +/- 5.7%. Vagally induced negative inotropism was almost completely prevented by microinjection of a ganglionic blocking drug into the CV ganglion. However, these injections into the CV ganglion did not significantly effect vagally induced decreases in either SA rate or AV conduction. We conclude: (1) that ganglia are found in a fat pad on the surface of the left ventricle of the cat heart and (2) that the CV ganglion selectively mediates the negative inotropic effect of vagal stimulation on the left ventricle. Greater understanding of the physiological functions of intracardiac neuronal circuits may help in developing new strategies to treat disorders of cardiac contractility such as congestive heart failure.

Animals↗
PubMed1997

Radial scars: a review of 30 cases.

Radial Scars/Complex Sclerosing Lesions are benign breast lesions that are seen more frequently now with the advent of screening mammography. These lesions need to be excised surgically in the absence of classical diagnostic features.

Breast↗
PubMed1997

The effect of changes in dietary fat on the food group and nutrient intake of 4- to 10-year-old children.

OBJECTIVE: To determine how young children changed their overall diet when they changed their fat intake after 3 months of participating in a nutrition education demonstration study designed to lower low-density lipoprotein cholesterol and cardiovascular risk. METHODS: Three 24-hour dietary recalls were collected from 303 4- to 10-year-old children at baseline and 3 months later. At both times, mean number of servings from food groups, grams of fat contributed from food groups, and intake of calories and nutrients were calculated and compared among quartiles of children formed according to change in their percent of calories from total fat after 3 months. RESULTS: Children who reduced their percent of calories from total fat most (ie, by an average of 8.5%) after 3 months consumed fewer servings from meats, eggs, dairy, fats/oils, and breads but tended to increase their number of servings from lower-fat foods within those food groups, particularly from dairy foods. These children also increased their mean intake of fruits, vegetables, and desserts, and maintained average intakes of all nutrients (except vitamin D) in excess of two thirds of the respective recommended dietary allowance. CONCLUSIONS: Young children who reduced their percent of calories from total fat in accordance with the current National Cholesterol Education Program recommendations accomplished this by reducing their overall intake of higher-fat foods, replacing higher-fat foods with lower-fat foods within several food groups, particularly within the dairy group (eg, drinking skim milk instead of whole milk) and by consuming more servings of fruits, vegetables, and very-low-fat desserts. These behaviors did not compromise their mean calorie or nutrient intakes, showing that it is possible for young children to lower their fat intake safely to reduce their risk of future heart disease.

Child↗
PubMed1996

Change in nutrient intakes, number of servings, and contributions of total fat from food groups in 4- to 10-year-old children enrolled in a nutrition education study.

OBJECTIVE: To determine change in nutrient intakes, number of servings, and contributions of total fat from food groups in children who lowered their dietary fat intake. DESIGN: A research and demonstration study designed to lower plasma low-density lipoprotein cholesterol level. There were four study groups: two intervention and two control groups. All children had hypercholesterolemia except for those in one control group. There 24-hour dietary recalls were collected on randomly assigned days over a 2-week period at baseline and 3 months after the intervention. SUBJECTS: Three hundred three 4-to 10-year old children from suburbs north of Philadelphia, Pa. INTERVENTIONS: One intervention involved a home-based, parent-child autotutorial program (PCAT group) with audiotaped stories and print materials for the children and their families; the other intervention involved one face-to-face counseling session with a registered dietitian (counseling group). OUTCOME MEASURES: Change in mean nutrient intakes compared with the Recommended Dietary Allowance (RDA); change in number of servings and mean grams of total fat contributed from 10 different food groups. STATISTICAL ANALYSES PERFORMED: Analyses of variance and chi 3 analyses. RESULTS: Children in every study group had mean intakes of all nutrients (except vitamin D) greater than 67% of the RDA 3 months after the baseline measurement. Several food groups (ie, meats, dairy products, fats/oils, and desserts) provided less total fat to the diets of children who reduced their dietary lipid intake after 3 months (i.e., PCAT and counseling groups). These children also reduced the mean number of servings selected from these food groups. Within these same food groups, some children consumed fewer servings of higher fat foods and more servings of lower fat foods. APPLICATIONS/CONCLUSIONS: Children who lowered their dietary fat intake after intervention reported both quantitative and qualitative changes in food choices from several food groups. These choices did not significantly reduce their nutrient intakes.

Aging↗
PubMed1996

Two-year outcome of social skills training and group psychotherapy for outpatients with schizophrenia.

OBJECTIVE: The authors evaluated the effectiveness of behaviorally oriented social skills training and supportive group therapy for improving the social adjustment of schizophrenic patients living in the community and for protecting them against psychotic relapse. METHOD: Eighty male outpatients with schizophrenia were stabilized with a low dose of fluphenazine decanoate (5 to 10 mg every 14 days), which was supplemented with oral fluphenazine (5 mg twice daily) or a placebo when they first met criteria for a prodromal period. (Half of the patients did so at some time during the study.) Patients were randomly assigned to receive either social skills training or supportive group therapy twice weekly for 6 months and then weekly for the next 18 months. Rates of psychotic exacerbation were monitored, as were scores on the Social Adjustment Scale II. RESULTS: There were significant main effects favoring social skills training over supportive group therapy on two of the six Social Adjustment Scale II cluster totals examined (personal well-being and total) and significant interactions between psychosocial treatment and drug treatment for three items (external family, social and leisure activities, and total). In each case, these interactions indicated that the advantage of social skills training over supportive group therapy was greatest when it was combined with active drug supplementation. Social skills training did not significantly decrease the risk of psychotic exacerbation in the full group, but an advantage was observed (post hoc) among patients who received placebo supplementation. CONCLUSIONS: These findings suggest that social skills training resulted in greater improvement in certain measures of social adjustment than supportive group therapy. The greatest improvement in social outcomes occurred when social skills training was combined with a pharmacological strategy of active drug supplementation at the time prodromal worsening of psychotic symptoms was first observed. However, these improvements were modest in absolute terms and confined to certain subgroups of patients.

Adult↗
PubMed1995

Scanning electron microscopy of Polystoma integerrimum (Monogenea, Polystomatidae).

The tegumental surfaces of both the bladder (normal) adult and branchial (neotenic) adult of the dimorphic monogenean Polystoma integerrimum are elevated into ridges forming a honeycomb-like pattern of hexagons. In some regions, upright microvilli are located at the angles of the hexagons. The two hamuli of the adult forms are sheathed with the ornamented tegument except for the naked distal spine. Larvae with haptors at the two-sucker stage of development have a tegument with the elevated honeycomb design characteristic of the adults. Developing hamuli appear as fully sheathed, conical elevations. The 16 marginal hooklets of the larval haptor are covered by tegument, with the exception of their strongly curved spines. Genetic blueprints for normal and neotenic development, contained in the genome of all larvae hatching from the eggs of normal individuals, appear to diverge only in relation to the different rates of embryonic development of the two adult forms and the incomplete ontogeny of the neotenic adult.

Animals↗
PubMed1995

The virus causing encephalomyelitis in sheep in Spain: a new member of the tick-borne encephalitis group.

The nucleotide and deduced primary amino acid sequence of the envelope gene of two virus isolates from the brains of Spanish sheep with encephalomyelitis, were determined and compared with those of other flaviviruses. The amino acid alignments showed that the Spanish viruses shared 95 to 96 per cent homology with the envelope protein of louping ill virus and western European tick-borne encephalitis virus. In comparison, the maximum variation in amino acid identities among strains of louping ill virus from the British Isles is 1.8 per cent. The Spanish isolates were distinguishable from all other known flaviviruses by the presence of a unique tripeptide sequence (AQR) at amino acid positions 232 to 234 in the E protein, the position at which a genetic marker for distinct flavivirus species has been identified. Other genetic markers, viz DSGHD (amino acids 320 to 324) and EHLPTA (amino acids 207 to 212), which identify the tick-borne encephalitis group within the genus Flavivirus, were present in the amino acid sequences of the Spanish virus. It is concluded that the cause of sheep encephalomyelitis in Spain is a distinct species in the tick-borne encephalitis virus group.

Animals↗
PubMed1995

Prospective identification and triage of nonemergency patients out of an emergency department: a 5-year study.

STUDY OBJECTIVE: To determine whether nonemergency patients can be prospectively identified by triage nurses and safely triaged out of the emergency department without treatment. METHODS: All adult patients (16 years or older) who presented to a university ED were provided an evaluation by a triage nurse. For a patient's case to be defined as nonemergency, four criteria were required: vital signs within a specific range, presence of 1 of 50 potentially nonemergent chief complaints, absence of key indicators found on screening examination, and absence of chest pain, abdominal pain, any severe pain, and inability to walk. Between July 1988 and July 1993, patients who satisfied these criteria were defined as nonemergency, refused care in the ED, and triaged out of the ED. Patients were referred to off-site clinics. The clinics had agreed to see patients in advance of the study, and the referral lists were frequently updated. Outcome data were obtained by telephone surveys to both triaged individuals and other health care providers. RESULTS: In this 5-year study, 176,074 adults presented to the ambulatory triage area in the ED, and 31,165 (18%) were defined as nonemergency, were not treated, and were referred elsewhere. Letters and telephone calls to all referral clinics, eight local EDs, and the coroner's office identified no instances of gross mistriage and only a small number of insignificant adverse outcomes. Telephone follow-up to individuals triaged away was successful in 34% of calls and showed that 39% of persons received care elsewhere on the same day, 35% received care within 3 days, and 26% decided not to seek medical care. A group of 1.0% sought care at other hospital EDs for minor complaints. CONCLUSION: A subset of patients with nonemergency problems can be prospectively identified and triaged out of the ED without significant adverse outcomes provided there is community support for follow-up care.

Adult↗
PubMed1995

Quantitative study of synaptophysin immunoreactivity of cerebral cortex and spinal cord in motor neuron disease.

Synaptophysin immunoreactivity can be quantified by image analysis to evaluate loss of presynaptic terminals in human neurodegenerative diseases. The extent and regional distribution of such loss is reported in motor neuron disease (MND). Autopsy samples of spinal cord and cerebral cortex were examined from 28 cases of MND and 28 age and sex matched controls. The MND group included individuals with amyotrophic lateral sclerosis (17[ALS]), and progressive muscular atrophy (11[PMA]). In the spinal cord, there was significant reduction of presynaptic terminals in the lateral ventral horn (15%) in both the ALS (p < 0.01) and PMA (p < 0.05) groups. Perisomatic synaptophysin profiles on lower motor neurons are preserved late in the disease and are not related to corticospinal innervation. Less marked presynaptic loss was demonstrable more widely in the medial ventral, intermediate and dorsal spinal grey matter (10%) in both ALS (p = 0.03) and PMA (p = 0.05). In the cerebral cortex no synaptic loss was demonstrated in motor or anterior cingulate regions in any of the MND cases. Spinal degeneration in MND is associated with loss of presynaptic terminals in all grey matter regions. It is most marked in the limb motor neuron area and is independent of corticospinal tract degeneration. The cerebral pathology of ALS is not associated with significant loss of presynaptic terminals in the cortical areas studied.

Adult↗
PubMed1995

The safety and effectiveness of brain arteriovenous malformation embolization using acrylic and particles: the experiences of a single institution.

The purpose of this article is to report on the safety and effectiveness of brain arteriovenous malformation (AVM) embolization for two series of patients, of which one was treated with particulate embolization and the other with acrylic embolization. Sixty-five consecutive patients from embolization logs and patient records from 1988 to 1993 were reviewed. AVMs were routinely treated with particulate embolization early in the review (1988-1991), and after a transition period, the technique was changed to acrylic embolization for the remainder of the study period (1992-1993). All patients were treated with the ultimate goal of complete AVM obliteration. AVMs were embolized and resected, if possible, and if unresectable, they were reduced in size with embolization and radiated. The course of treatment for each patient was reviewed. The effectiveness at the end of treatment was analyzed for the ability to resect the AVM and, if unresectable, the ability to reduce the AVM to radiation size. Additionally, the safety of each embolization technique was evaluated in the context of comprehensive care, in terms of the safety of the procedure itself, the surgical resection after embolization, and the outcome at the end of comprehensive treatment. This article outlines the safety and effectiveness of acrylic and particulate embolization at a single institution. The ability to surgically resect an AVM after embolization and to reduce nidus size with acrylic was at least comparable with that with particulate embolization. Comprehensive complication rates were lower after acrylic embolization and were heavily influenced by a decreased number of surgical complications in the acrylic series. These data support the need to conduct a randomized prospective clinical trial to compare the relative safety and effectiveness of the two methods of embolization.

Acrylic Resins↗
PubMed1994

Characterization of type I procollagen N-proteinase from fetal bovine tendon and skin. Purification of the 500-kilodalton form of the enzyme from bovine tendon.

Procollagen N-proteinase (EC 3.4.24.14) is the enzyme that specifically cleaves the NH2-terminal propeptides from type I procollagen. Two forms of N-proteinase with apparent molecular sizes of 300 and 500 kDa were found in partially purified preparations from fetal bovine tendon extracts. The 500-kDa form of enzyme was purified 16,000-fold with a recovery of 8% from the extracts of the tendons by six purification steps. The purified enzyme was a neutral, Ca(2+)-dependent proteinase (5-10 mM) that was inhibited by metal chelators. The 500-kDa enzyme contained unreduced polypeptides of 58, 125, 170, and 190 kDa which were separated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. Electron microscopic study indicated that the enzyme molecules were generally globular and had diameters of 33 +/- 4 nm. Other properties of the 500-kDa enzyme were: 1) the Km for type I procollagen is 35 nM at pH 7.5 and 35 degrees C, and the kcat is 290 h-1; 2) the activation energy for reaction with type I procollagen is 10,050 cal mol-1; 3) the isoelectric point is 3.8; 4) the enzyme cleaves the NH2-terminal propeptides of type II procollagen as well as type I procollagen but not of type III procollagen; and 5) the enzyme specifically cleaves a -Pro-Gln- bond in the pro-alpha 1(I) chain and an -Ala-Gln- bond in the pro-alpha 2(I) chain. The bovine N-proteinase with a mass of 300 kDa was found to be similar to the 500-kDa enzyme and appeared to be a degraded form of the 500-kDa enzyme generated during purification. The N-proteinase from fetal bovine skin extracts also contained 300-kDa and 500-kDa enzyme forms.

Amino Acid Sequence↗
PubMed1994

Fluphenazine vs placebo supplementation for prodromal signs of relapse in schizophrenia.

BACKGROUND: We studied the effectiveness of treating patients with low doses of fluphenazine decanoate and supplementing them with oral fluphenazine when there was evidence of prodromal symptoms of psychotic exacerbations. METHODS: Eighty schizophrenic patients who were receiving 5 to 10 mg of fluphenazine decanoate every 2 weeks were monitored for prodromal symptoms using an idiosyncratic prodromal rating scale. When patients met our criteria for a prodromal episode, they were randomly assigned to a double-blind comparison of oral fluphenazine hydrochloride (5 mg twice daily) or a placebo for the current and future prodromal episodes. We compared rates of psychotic exacerbations in the two treatment groups. RESULTS: Thirty-six patients (45%) met the criteria for a prodrome at some point during the trial and were randomized to drug or placebo. Using survival analysis during the entire 2 years, we did not find a significant difference between fluphenazine and placebo in the likelihood that a prodrome would continue to an exacerbation. Survival analysis beginning at the start of the second year of treatment did indicate a significant reduction in exacerbation risk for patients receiving drug supplementation (P = .032). Similarly, there was no difference between the two groups in the proportion of time at risk spent in exacerbation during the first year, but patients receiving active drug supplementation spent less time in an exacerbated state in the second year (P = .05). CONCLUSIONS: Our treatment strategy appeared to be effective for some patients, particularly those who were able to remain in the study beyond the first year. Although the occurrence of a prodrome was a fairly good marker that a patient was at high risk of ultimate exacerbation with our low-dose maintenance protocol, prodromes were not highly sensitive indicators of imminent exacerbation.

Acute Disease↗
PubMed1993

A trainer's perspective of an innovative programme teaching health visitors about the detection, treatment and prevention of postnatal depression.

Health visitors in North Staffordshire, Edinburgh and Lewisham were given the opportunity to participate in a training programme in the detection, treatment and prevention of postnatal depression, based on previously reported successful intervention strategies. They were trained in the use of the Edinburgh Postnatal Depression Scale (EPDS), and given information about the value and practice of non-directive counselling and about preventative strategies. Knowledge acquisition was evaluation by self-report questionnaires given before and after training. The health visitors were encouraged to screen postnatal women at three specified times using the EPDS and to offer non-directive counselling to women who obtained high scores. A baseline measure of the incidence of postnatal depression was obtained by asking health visitors to give an EPDS form to all women in their caseload with a 6-month-old baby before training commenced. A comparison of the number of women with high EPDS scores at 6 months postnatally, before and after training, showed that participation in the programme enabled health visitors to positively influence the emotional well-being of postnatal women. These results have implications for the role of health visitors which is currently being challenged, as well as for components of their training and continuing professional development.

Community Health Nursing↗
PubMed1993

Patients' perceptions of family emotional climate and outcome in schizophrenia.

Thirty-nine chronic schizophrenic male out-patients and their relatives were interviewed separately to assess their perceptions of their current relationships. Two simple 5-point rating scales predicted the risk of psychotic exacerbation during a one-year follow-up: patients' perceptions of the relatives' attitudes towards them, and patients' own attitudes towards the relatives. Survival analysis of data in a 2 x 2 factorial--combining degree of contact with the key relatives and the patients' perceptions of their relatives--found that patients in frequent contact with a positively perceived relative had significantly better survival rates without psychotic exacerbation. Patients' perceptions of their relatives may help identify patients at risk of exacerbation of their illness.

Adolescent↗
PubMed1992

New method for describing the performance of cardiac surgery cannulas.

Cardiac surgery cannulas are characterized by external diameter only, which provides little information about the pressure-flow characteristics of a cannula. A system has been developed to describe pressure-flow characteristics with a single, unitless number, M, which is patterned after a Reynolds friction factor correlation. A cannula with a lower M number has a more favorable pressure-flow relationship. The M number was determined for 16 arterials cannulas ranging in size from 10F to 26F and 27 venous cannulas sized 12F to 36F. Pressure-flow characteristics vary considerably among cannulas from different manufacturers despite having similar French sizes. Clinical decisions regarding choice of cannula can be simplified by using the M number, which gives a more accurate description of the performance characteristics of a cannula than the French size designation.

Cardiac Catheterization↗
PubMed1992

Complex effects of arachidonic acid and its lipoxygenase products on cytosolic calcium in GH3 cells.

The mechanisms by which arachidonic acid (AA) and its metabolites stimulate prolactin release from pituitary cells are not understood. Because Ca2+ ions are pivotal to exocytosis, we investigated the effects of AA metabolites on intracellular calcium concentration ([Ca2+]i) and membrane ionic currents using dual-excitation microspectrofluorimetry and whole cell patch-clamp techniques in GH3/B6 pituitary line cells. AA (1 microM) had a biphasic effect on [Ca2+]i, mobilization of intracellular Ca2+, followed by stimulation of Ca2+ entry. Only the latter appeared to result from the degradation of AA through the lipoxygenase pathway. Indomethacin (Indo, 10 microM) and lipoxygenase products 5-, 12-, and 15-hydroxyeicosatetraenoic acid (HETE, 1 microM), increased action potential duration (12-HETE) or frequency (5- and 15-HETE, Indo). These effects depended on inhibition of d-tubocurarine- or tetraethylammonium-sensitive K+ conductances and stimulation of voltage-dependent Ca2+ channels. Refilling of intracellular Ca2+ stores, and Ca2+ efflux, may also be stimulated. Our results demonstrate a control of [Ca2+]i by a second messenger (AA) and its metabolites (HETEs).

Arachidonic Acid↗