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Biomedical subjects

R Morris

Publications and source records attributed to R Morris.

At least 145 records · Page 8Linked to original sources
PubMed1997

Activation of human macrophage fungistatic activity against Histoplasma capsulatum upon adherence to type 1 collagen matrices.

Human monocyte/macrophages (Mphi) were adhered to extracellular matrix proteins, and the intracellular growth of Histoplasma capsulatum (Hc) yeasts were quantified and compared with their growth in Mphi adhered to plastic. Freshly isolated monocytes and cultured monocyte/derived Mphi adhered to type 1 collagen gels, but not to nongelled collagen-, fibronectin-, laminin-, or vitronectin-coated surfaces, demonstrated significant fungistatic activity against Hc yeasts. Activation of Mphi developed immediately upon adherence to the collagen matrices (1 h) and did not require additional time in culture. In addition, many of the yeasts were digested by 24 h postinfection. Mphi adhered to collagen maintained their fungistatic activity for up to 4 days, during which time monolayers cultured on plastic were destroyed. Culture of Mphi in the presence of IFN-gamma or TNF-alpha for 24 h before infection did not augment the fungistatic activity of collagen-adherent Mphi. Likewise, culture of monocytes on collagen gels with IL-3, granulocyte-Mphi CSF (GM-CSF) or Mphi CSF (M-CSF) for 7 days did not enhance Mphi fungistatic activity above that obtained by monocytes cultured on collagen alone. The mechanism(s) of Mphi-mediated fungistasis was not associated with production of toxic oxygen radicals, nitric oxide, or the restriction of intracellular iron. However, experiments with horseradish peroxidase-labeled gold colloids and immunoelectron microscopy demonstrated that phagolysosomal fusion, which is minimal in Hc-infected Mphi adhered to plastic, is enhanced significantly at both 1 h and 24 h postinfection in Mphi adhered to collagen matrices. These data suggest that in vivo, matrix-bound Mphi may express a previously unrecognized antifungal activity that proceeds in the absence of exogenous cytokines and is mediated, in part, by overcoming the capacity of Hc yeasts to inhibit Mphi phagolysosomal fusion.

Cell Adhesion↗
PubMed1997

Xanthomonas maltophilia endophthalmitis after cataract extraction.

PURPOSE: To report a case of Xanthomonas maltophilia endophthalmitis and to increase awareness of its potential as an intraocular pathogen. METHOD: Case report. RESULTS: A 76-year-old woman developed X maltophilia endophthalmitis after cataract extraction. To eradicate the infection, we performed two vitrectomies and treated the patient with numerous intravitreal antibiotic injections. CONCLUSIONS: X maltophilia is a potential intraocular pathogen in an immunocompetent host. If the infection takes a persistent course, persistent topical and intravitreal antibiotic treatment and possibly vitrectomy are needed to eradicate the infection.

Aged↗
PubMed1997

Limited success using the "flare" protocol in poor responders in cycles with low basal follicle-stimulating hormone levels during in vitro fertilization.

OBJECTIVE: To assess an alternate protocol for stimulating poor responders. DESIGN: Prospective clinical study. SETTING: University-affiliated infertility clinic. PATIENT(S): Eighty poor responders. INTERVENTION(S): Stimulation was withheld until patients fulfilled the following criteria: basal FSH < or = 12 mIU/mL (conversion factor to SI unit, 1.00) with concurrent E2 level < or = 100 pg/mL (conversion factor to SI unit, 3.671), and P level < or = 1.0 ng/mL (conversion factor to SI unit, 3.467). They then started leuprolide acetate on cycle day 2 and a high dose of gonadotropins on cycle day 3. MAIN OUTCOME MEASURE(S): Stimulation response and pregnancy rates (PRs). RESULT(S): Nineteen cycles (23.8%) were canceled because of poor ovarian response. The mean E2 level on day of hCG was 2,578 +/- 1,339 pg/mL (9,464 +/- 4,915 pmol/L) (range, 789 to 5934 pg/mL [2,896 to 21,784 pmol/L]). The number of oocytes retrieved was 10 +/- 6.6 (range, 1 to 37). Nine patients did not have ET (failed fertilization [n = 5], no cleavage of preembryos [n = 3], freeze all [n = 1]). The number of pre-embryos transferred was 3.9 +/- 1.6 (range, 1 to 8). The clinical pregnancy rate was 7 of 61 (11.5%) per retrieval, and 7 of 52 (13.4%) per transfer with an implantation rate of 7 of 201 (3.5%). Three patients miscarried with an ongoing PR of 4 of 61 (6.5%) per retrieval and 4 of 52 (7.6%) per transfer. CONCLUSION(S): Poor responders undergoing controlled ovarian hyperstimulation with the "flare" protocol in cycles with low basal FSH will often show adequate ovarian response and reach oocyte retrieval and ET. The PRs, however, remain low.

Adult↗
PubMed1997

A neuroanatomical method to assess the integrity of fibers of passage following ibotenate-induced damage to the central nervous system.

In some behavioral-lesion experiments involving animals, ibotenic acid (IBO) is used as a means of damaging brain structures. Occasionally one needs to assess the status of fibers coursing through the damaged area to determine whether the deficits observed are the result of destruction of neurons rather than fibers. In such cases, IBO, is considered to be the method of choice since it destroys cell bodies but leaves fibers of passage intact. However, if the IBO dose injected in a given area is too high, both cell bodies and fibers of passage could be damaged. The anterograde and retrograde tracer wheat germ agglutinin-horseradish peroxidase (WGA-HRP) is a useful technique to verify that fibers are intact, and is a more powerful tool in comparison with a tracer, such as HRP, which has been used in previous studies.

Amygdala↗
PubMed1997

Pulmonary embolism from in situ right atrial thrombus after coronary artery bypass surgery.

Pulmonary embolism after cardiac surgery is attributed to embolization from thrombus within the deep venous system. We report two cases of pulmonary embolism after coronary artery bypass surgery in which transesophageal echocardiography detected in situ right atrial thrombus. The right atrium should be screened for thrombus in patients who have pulmonary embolism after cardiac surgery.

Aged↗
PubMed1997

Delay versus deviance in autistic social behavior.

The pattern of acquisition of social, communication, and daily living skills was examined for autistic children, compared to retarded and normal controls, by quantifying intradomain scatter on the Vineland Adaptive Behavior Scales. Autistic children were matched to normal children and mentally retarded children on Vineland raw scores; group differences in scatter were examined for each domain of adaptive behavior. Autistic children had significantly more scatter on Communication and Socialization than both control groups. Item analyses showed that the autistic children had particular weaknesses on items reflecting attention to and pragmatic use of language, as well as play and reciprocal social interaction; the autistic children had particular strengths on items reflecting written language and rote language skills, and rule-governed social behavior. The number of items showing consistent group differences, however, was small, suggesting that although autistic development appears sequentially deviant and not merely delayed, individual autistic children derive their scatter from different items, and are a developmentally heterogeneous group.

Activities of Daily Living↗
PubMed1997

Effects of methylphenidate on attention and nonverbal learning in children with attention-deficit hyperactivity disorder.

OBJECTIVE: To examine effects of methylphenidate (MPH) doses on attention and learning tasks requiring varying levels of processing in 23 children with attention-deficit hyperactivity disorder. METHOD: Performance on a continuous performance task (CPT) and two difficulty levels of a nonverbal learning task was evaluated on two doses of MPH (0.3 mg/kg and 0.8 mg/kg) and placebo. RESULTS: CPT commission errors were significantly reduced with low-dose MPH compared with placebo while omission errors were not medication-sensitive. Performance on nonverbal learning tasks was significantly improved with MPH. On the easy level of the nonverbal learning task performance improved equally well with either dose. On the hard level, performance was significantly better at the high dose compared with placebo; no between-dose differences emerged across learning trials. However, the high dose was superior to low and placebo doses in memory recall trials. CONCLUSIONS: Impulsivity may be reduced on an attentional task with a low dose of MPH, and a high dose of MPH may optimize retention and recall of complex nonverbal information.

Analysis of Variance↗
PubMed1997

Screening for ocular hemorrhages in patients with ruptured cerebral aneurysms: a prospective study of 99 patients.

BACKGROUND: Terson's syndrome (vitreous hemorrhage) and other ocular hemorrhages (retinal hemorrhages) have been reported to occur in up to 40% of patients with ruptured cerebral aneurysms. Because microsurgical vitrectomy can safely restore vision in patients with visual loss secondary to Terson's syndrome, we hypothesized that prospectively screening a selected group of patients with aneurysms would result in a higher rate of vitrectomy in patients with more extensive subarachnoid hemorrhage. METHODS: Ninety-nine patients with ruptured cerebral aneurysms were prospectively screened for Terson's syndrome and other forms of ocular hemorrhage by an ophthalmologist. Follow-up data were obtained for seven of eight cases of Terson's syndrome, and vitrectomy was performed for visual restoration when indicated. RESULTS: Ocular hemorrhages were present in 17% of patients with ruptured cerebral aneurysms, and Terson's syndrome was present in 8% of patients. Screening of patients with histories of transient or prolonged comas sensitively identified patients with ocular hemorrhages in 100% of the patients with Terson's syndrome and 89% of the patients with other ocular hemorrhages. Fifty-five percent of the patients in the overall series had histories of transient or prolonged comas, and 53% (specificity) of those patients had ocular hemorrhages. Two of the eight patients with Terson's syndrome underwent vitrectomy, with dramatic improvement in vision. No other ocular hemorrhages required surgery. CONCLUSIONS: Ophthalmological screening of patients with histories of transient or prolonged comas after ruptured cerebral aneurysms very sensitively identifies patients with ocular hemorrhages, which are relatively common in patients with subarachnoid hemorrhage treated in an academic neurosurgical practice. The present study underestimates the true incidence of Terson's syndrome in that patients who died shortly after their subarachnoid hemorrhage were not included. Vitrectomy for patients who do not exhibit spontaneous improvement in vision results in a dramatic reversal of blindness.

Adult↗
PubMed1997

Quantitative vitreous collection using a modified infusion fluid during vitrectomy.

PURPOSE: To develop a vitreous sampling method that increases yield while reducing risk of harm to the patient. METHODS: Potential negative effects of fluoresceinated BSS infusion solution on biologic activity were assessed by monitoring changes in fibroblast contraction of collagen gels in response to serum or vitreous. Paired vitreous samples were collected from ten patients before and during infusion of fluoresceinated BSS solution. The extent to which the vitreous was diluted was calculated by comparing the levels of fluorescence in the samples with that in fluoresceinated BSS. Protein concentrations and levels of contraction-stimulating activity were measured for each sample. RESULTS: Fluoresceinated BSS did not alter fibroblast morphology, rate, or extent of gel contraction. Differences in corrected protein concentrations and biologic activities of the undiluted and diluted homogenous vitreous samples were not statistically significant. CONCLUSIONS: The use of fluoresceinated BSS infusion yields larger vitreous samples from which the native biochemical characteristics can be determined. Patient safety during collection is enhanced because ocular hypotony and collapse can be avoided.

Body Fluids↗
PubMed1997

Acute effects of oral glibenclamide on blood pressure and forearm vascular resistance in diabetics.

1. To determine the effects of an acute oral dose of glibenclamide on blood pressure (BP), basal forearm vascular resistance (FVR) and FVR responses to the K+ATP channel activating vasodilator diazoxide, a placebo-controlled, double-blind cross-over study was performed in eight male volunteers with non-insulin-dependent diabetes mellitus. 2. Changes in vascular responses to progressively increasing concentrations of diazoxide (3.75-30 mg/kg per min) and noradrenaline (25-100 ng/kg per min) were measured by venous occlusion plethysmography. 3. Glibenclamide significantly lowered plasma glucose levels compared with placebo (P < 0.02) and attenuated the decrease in FVR (P < 0.05) and the decrease in systolic BP (P < 0.05) that followed a meal. However, vasodilator responses to diazoxide were potentiated by the administration of oral glibenclamide (P < 0.01). 4. Acute administration of oral glibenclamide attenuates the normal decrease in FVR and systolic BP that follows a meal and potentiates rather than inhibits forearm vasodilator responses to intra-arterial diazoxide, probably via indirect humoral effects. These results suggest that glibenclamide has direct or indirect vasoconstrictor effects that antagonize the normal increase in forearm blood flow that follows a meal and that the inhibition of vascular K+ATP channels following acute oral glibenclamide administration is clinically insignificant compared with other indirect vascular effects of the drug.

Adenosine Triphosphate↗
PubMed1997

Cryptosporidium sp. Infections in Green Turtles, Chelonia mydas, as a Potential Source of Marine Waterborne Oocysts in the Hawaiian Islands.

For the first time, Cryptosporidium sp. oocysts were identified in fecal and intestinal samples from free-ranging marine turtles, Chelonia mydas, from the Hawaiian Islands. The oocysts produced positive reactions with commercial test kits recommended for the detection of human-infectious waterborne oocysts of Cryptosporidium parvum.

Journal Article↗
PubMed1997

Intrathecal urokinase as a treatment for intraventricular hemorrhage in the preterm infant.

Despite improvements in the care of preterm infants, intraventricular hemorrhage (IVH) and posthemorrhagic hydrocephalus (PHH) continue to be frequent occurrences in this patient population. Shunt procedures in these children are frequently complicated by obstruction and/or infection. As the hydrocephalus is usually caused by an obliterative arachnoiditis due to contact of the blood with the basilar meninges, it was postulated that infusion of urokinase into the ventricles of infants who have sustained an IVH would clear the blood, mitigate the arachnoiditis, and prevent the progression of PHH. Accordingly, 18 preterm infants who had sustained IVH and subsequently developed PHH were treated with intraventricular urokinase instilled via a surgically implanted subcutaneous reservoir. There were no complications associated with the urokinase. Infants were divided into two dosage groups: low dose (110,000-140,000 IU total) and high dose (280,000 IU total). One infant in the low-dose group died at 1 month of life of respiratory complications. In the low-dose group, 3 of 8 (37%) infants required shunt placement; in the high-dose group, all 9 required shunt placement. For the total group, the shunt rate was 71%. This compares to a historical control group shunt rate of 92%. While the difference between the treatment group as a whole and control group approaches, but does not reach, statistical significance (p = 0.068), there was a significant reduction in the shunt rate when the low-dose group was considered separately (p < 0.002). For those infants that required shunt placement, there were fewer shunt revisions performed in the treatment group than in the control group during the first 24 months following shunt placement: 0.67 versus 1.5 shunt revisions/shunted child. Initial experience with intraventricular urokinase following IVH and PHH in preterm infants suggests a beneficial effect in reducing the shunt revision rate in both high- and low-dose groups. Reduction in shunt placement rate is seen only in the low-dose group.

Animals↗
PubMed1997

Australasian perfusion incident survey.

An anonymous postal survey about perfusion accidents, incidents and safety procedures was conducted retrospectively in all identifiable cardiac surgery units in Australia and New Zealand over an 18-month period from January 1994 to July 1995. Responses were received from 69% of all eligible perfusionists representing 39 to 42 operating units. The most frequent incidents reported were heater/cooler failure (43% of respondents), urgent return to bypass following circuit disposal (38%), air embolus in a circuit not reaching the patient (24%), accidental cannula displacement (28%), protamine-induced circuit clotting postbypass (20%), hospital power failure (31%) and oxygenator membrane leaks (24%). There were 11 serious injuries and 10 deaths reported, giving an overall rate of serious injury or death of one in 1300 cases. However, the perfusion-related injury rate was lower, at one injury or death per 2500 perfusions. The use of safety equipment was widespread with low-level alarms in use by all respondents, bubble detectors by 74%, arterial line filters by 82% and written or computerized checklists by 80%. While the rate of injury was lower than that reported in surveys done elsewhere, the rate of reporting of incidents was greater and this may reflect a changing attitude of perfusionists to accountability in the delivery of their services. The data suggest that the level of safety in perfusion in Australasia is high but that improved incident reporting may help to further improve practices.

Australia↗
PubMed1997

Use of chest computed tomography in the staging of pediatric Wilms' tumor: interobserver variability and prognostic significance.

PURPOSE: To determine the specificity and prognostic significance of computed tomography (CT) of the chest in pediatric Wilms' tumor. PATIENTS AND METHODS: Patients treated for newly diagnosed Wilms' tumor at St Jude Children's Research Hospital between December 1978 and July 1995 were included in the study if an initial chest radiograph and CT were available and if pulmonary involvement (determined by chest radiographs) was absent. For the 202 patients studied, radiographs and CT scans were reviewed blindly and independently by three experienced radiologists for the presence of pulmonary nodules. Outcome variables consisted of intraobserver variability (in a subsample of 40 cases) and concordance between ratings on radiographs and CT scans (both by McNemar's test), interrater variability (by logistic regression), and the cumulative incidence of pulmonary relapse for patients with and without positive CT scans, by reviewer. RESULTS: As expected, ratings of pulmonary involvement on radiographs were discordant with CT ratings. There was marked variability among reviewers in CT ratings (P = .0001). Of 202 CT scans, 78 were read as positive by at least one reviewer, 41 were rated positive by only one reviewer, 18 by two reviewers, and 19 by all three. Intrarater variability on repeat reviews was not significant. Patients with nodules identified on CT had a significantly higher pulmonary relapse rate when analyzed separately by reviewer. However, for the 14 patients who had pulmonary relapse, CT scans were rated positive by all three reviewers in only five cases and as negative by all three in another five cases. CONCLUSION: The variability in interpretation of chest CT scans in patients with Wilms' tumor limits the predictive utility of these studies. Optimal, standardized techniques and central review are essential if chest CT is to be used for staging in cooperative studies.

Adolescent↗
PubMed1997

Comparative effects of glibenclamide and metformin on ambulatory blood pressure and cardiovascular reactivity in NIDDM.

OBJECTIVE: To compare the effects of chronic glibenclamide and metformin therapy on blood pressure (BP) and cardiovascular responsiveness in patients with NIDDM. RESEARCH DESIGN AND METHODS: Fourteen patients with NIDDM received metformin or glibenclamide for 1 month in a double-blind, randomized crossover study. At the end of each treatment period, patients were tested for forearm vascular responsiveness to intrabrachial arterial infusion of diazoxide (an ATP-sensitive potassium channel opener), acetylcholine, sodium nitroprusside, and norepinephrine, BP responses to intravenous infusions of NE and angiotensin II, BP responses to cold pressor testing and isometric exercise, and 24-h ambulatory BP monitoring. RESULTS: Metformin and glibenclamide produced similar glycemic control. Mean 24-h BPs did not differ between the two groups, but mean 24-h heart rates were significantly lower (75 +/- 6 bpm vs. 80 +/- 6 bpm) on glibenclamide therapy than on metformin. Plasma norepinephrine levels were significantly higher on glibenclamide (6.41 +/- 1.77 vs. 4.26 +/- 1.54 mmol/l, P < 0.01), and systolic BP responses to intravenous norepinephrine and angiotensin II were significantly higher on glibenclamide than on metformin (P < 0.02 and P < 0.05, respectively). Systolic BP responses to cold pressor testing appeared higher on glibenclamide than on metformin, but the difference did not quite achieve statistical significance (P = 0.052). Baseline forearm vascular resistance did not differ between the two drugs, nor did forearm vascular resistance responses to diazoxide, acetylcholine, sodium nitroprusside, and norepinephrine differ. CONCLUSIONS: Glibenclamide therapy is accompanied by greater systolic BP responses to norepinephrine and angiotensin II and higher plasma norepinephrine levels than those that occur on metformin therapy. Lower heart rates on glibenclamide therapy despite evidence of greater sympathetic activity suggests that glibenclamide may have negative chronotropic effects.

Acetylcholine↗
PubMed1997

Increased expression of G1 cyclins and cyclin-dependent kinases during tumor progression of chemically induced mouse skin neoplasms.

Cyclins and cyclin-dependent kinases (Cdks) are central to regulation of the cell cycle. Their abnormal expression may cause loss of cell-cycle control and result in autonomous cell growth, a critical feature of neoplasias. In this study, using immunoblotting, we analyzed the protein levels of several G1/S cyclins (cyclins D1, D2, D3, A, and E) and their respective Cdks (Cdk 2, 4, and 6) in 17 mouse squamous cell carcinomas (SCCs) and 18 mouse skin tumor cell lines. Overexpression of these cell cycle-related genes was frequent in tumors and cell lines. Of special interest was the fact that a group of cell lines that became more aggressive after animal passaging expressed more cyclins D2 and D3 than their respective parental lines did. In addition, SCCs had higher cyclin D3 expression levels than papillomas, and metastases had higher levels than the respective primary tumors, indicating that overexpression of cyclin D3 may be associated with increased aggressiveness of mouse SCC. Interestingly, overexpression of cyclin E was seen in most SCCs induced by a complete carcinogenesis protocol with benzo[a]pyrene (B(a)P) and only in a few SCCs induced by a two-stage carcinogenesis protocol using 7,12-dimethylbenz[a]anthracene as initiator. In contrast, more of the latter tumors overexpressed cyclin D1 and D2 than those induced by B(a)P. Thus, it is possible that different components of the cell-cycle machinery are involved in proliferative dysfunctions that take place during tumor development with different carcinogenesis protocols. Taken together, these results indicate that overexpression of G1 cyclins and their related Cdks is a significant molecular abnormality that could be involved in the process of tumor progression.

9,10-Dimethyl-1,2-benzanthracene↗