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Biomedical subjects

M J Robinson

Publications and source records attributed to M J Robinson.

At least 55 records · Page 3Linked to original sources
PubMed1995

Pleomorphic liposarcoma of the pterygomandibular space involving the maxilla.

Liposarcoma of the head and neck is rare. Because of its rarity, we report this case of pleomorphic liposarcoma of the left pterygomandibular space, involving the maxilla, maxillary sinus, left lateral maxillary wall, left maxillary gingiva with extension into the buccal space, retro-orbital region, left mandibular ramus, and left zygomatic process. To our knowledge, there are only two other reported cases of liposarcoma involving the maxilla, one of which was a pleomorphic liposarcoma. The pertinent literature is reviewed with an emphasis on the importance of histopathologic classification.

Adolescent↗
PubMed1995

Studies on TGF-beta 1 gene expression in the intima of the human aorta in regions with high and low probability of developing atherosclerotic lesions.

Certain regions of the human aorta are at greater risk for early and more severe atherosclerotic lesions development than others. Cornhill and coworkers (Cornhill FJ et al.: Arteriosclerosis 5:415, 1985) created maps for the probability of developing atherosclerosis defining the high-probability region (HPR) in the dorsal descending thoracic aorta and the low-probability region (LPR) in the ventral descending thoracic aorta. Our study examines the hypothesis that transforming growth factor beta -1 (TGF-beta 1), a well-known suppressor of growth and function in many human cell lines, is one of the inhibitors of human atherogenesis. The present experiment analyzes the expression of mRNA for TGF-beta 1 in both the HPR and the LPR of aortas from young (age 17 to 25 y) males of black (n = 8) and white (n = 7) race. The level of TGF-beta 1 gene expression was assessed in the aortic intima in both the HPR and the LPR, using National Institutes of Health Image 1.47, an Apple Macintosh application capable of digital image processing, analysis, and morphometric measurement. There was significantly lower (P = 0.002, alpha = 0.05) TGF-beta 1 gene expression in the HPR than in the LPR in the 22- to 25-y age group. There was no significant difference in the 17- to 21-y age group and between the HPR and the LPR in the entire study group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Giardiasis diagnosed by biopsy of the colon and terminal ileum: unusual sites for a common pathogen.

Giardiasis is a common intestinal infection which commonly presents with nonspecific symptoms. Suspected cases are usually diagnosed by stool examination or duodenal aspirates or biopsies. The purpose of this case report is to alert physicians to the fact that the organism may be present in colonic and ileal biopsies when clinical symptoms prompt a clinician to perform colonic biopsies rather than the usual tests of stools and duodenal aspirates or biopsies.

Adult↗
PubMed1994

Microbial keratitis in children.

In a five-year review, we identified 29 cases of microbial infection in 28 patients who were 16 years old or younger. Herpes simplex infections were excluded. Predisposing factors included trauma (ten cases, 34%), severe systemic illness (eight cases, 27%), contact lens use (seven cases, 24%), exposure keratopathy (seven cases, 24%), and previous ocular surgery (six cases, 21%). A total of 24 microorganisms were identified in cultures of corneal scrapings from 22 of the 29 cases; two cases involved polymicrobial infections. Of the 24 identified pathogens, gram-positive cocci were the most common (12). Other microorganisms included gram-negative bacteria (five) and fungi (four). Isolated cases of Acanthamoeba species, Borrelia burgdorferi, and Bacillus species were also present. Therapy with intensive topical antibiotics was successful in this series. The rate of surgical intervention (6/29, 21%) was similar to that of previous reports.

Adolescent↗
PubMed1994

Heparin prevents antigen-induced airway hyperresponsiveness: interference with IP3-mediated mast cell degranulation?

We hypothesized that heparin, because of its antiallergic and/or anti-inflammatory properties, modifies airway hyperresponsiveness (AHR). We studied the effects of inhaled heparin on AHR induced by specific antigen or by platelet-activating factor (PAF), a proinflammatory mediator. Specific lung resistance (sRL) was measured in 17 allergic sheep before, immediately after, and serially for up to 2 h after airway challenge with either specific antigen or PAF. Airway responsiveness was expressed as the cumulative provocative dose of carbachol that increased sRL to 4 cmH2O/s [PD4, in breath units (BU; 1 BU = 1 breath of 1% carbachol solution)]. PD4 was determined on a baseline day and on various experimental days 2 h after airway challenge with antigen or PAF, without or after pretreatment with inhaled heparin (1,000 U/kg). Pretreatment with inhaled heparin prevented antigen-induced bronchoconstriction and postantigen AHR. PD4 was 26 +/- 2.6 (SE), 12 +/- 1.7, and 22 +/- 2.8 BU on baseline, antigen control, and postheparin days, respectively. Heparin given immediately after the antigen challenge failed to modify the magnitude and/or duration of antigen-induced bronchoconstrictor response or postantigen AHR. Heparin also failed to prevent PAF-induced changes in sRL and AHR. In vitro heparin inhibited anti-immunoglobin E- and 1,4,5-inositol triphosphate-mediated degranulation of rat peritoneal mast cells without attenuating the effects of the Ca2+ ionophore A-23187. These data suggest that in "acute responders" heparin prevents antigen-induced bronchoconstriction and AHR, possibly by inhibiting 1,4,5-inositol triphosphate-dependent mast cell mediator release and not by its anti-inflammatory action.

Animals↗
PubMed1994

Granulomatous lymphadenitis caused by Coccidioides immitis.

The dimorphic fungus Coccidioides immitis is endemic to regions of the southwestern United States, Mexico, and Central America. The mycelial form is highly infectious and is carried in dust, which is inhaled. The lung is primarily affected. The disease caused by this organism ranges from an asymptomatic form to the disseminated or progressive type. Diagnosis hinges on identification of fungal infection by means of biopsy, culture, serology, or skin testing. Each method has advantages and pitfalls. This report discusses a case of granulomatous lymphadenitis caused by C immitis which was diagnosed in the eastern United States by means of a lymph node biopsy.

Adult↗
PubMed1993

Effects of topoisomerase II-targeted drugs on enzyme-mediated DNA cleavage and ATP hydrolysis: evidence for distinct drug interaction domains on topoisomerase II.

Topoisomerase II is the target for two broad groups of clinically relevant drugs. Members of these groups are classically defined by their ability to enhance enzyme-mediated DNA cleavage (such as etoposide and m-AMSA) or to inhibit enzyme-catalyzed ATP hydrolysis (such as novobiocin). The above notwithstanding, little is known concerning the interactions of drugs in either mechanistic class with the topoisomerase II-DNA complex. In order to further delineate the mechanism of drug action, the effects of several topoisomerase II-targeted agents on the DNA cleavage and ATP hydrolysis steps of the enzyme's catalytic cycle were determined. Of the drugs examined (genistein, quercetin, quercitrin, etoposide, m-AMSA, CP-115,953, and novobiocin), only novobiocin was unable to enhance topoisomerase II-mediated DNA cleavage. Moreover, with the exception of etoposide, all of the drugs were found to inhibit enzyme-catalyzed ATP hydrolysis. This latter finding undercuts the common assumption that DNA cleavage-enhancing drugs are specific for the cleavage/religation activity of topoisomerase II. Finally, by utilizing a series of competition experiments that took advantage of mechanistic differences between drug classes, it was possible to functionally define drug interaction domains on the eukaryotic type II enzyme. Results of this novel approach indicate that the interaction domain for novobiocin on topoisomerase II is distinct from those of the DNA cleavage-enhancing drugs.

Adenosine Triphosphate↗
PubMed1993

Endothelin-1-induced reductions in cerebral blood flow: dose dependency, time course, and neuropathological consequences.

The capacity of endothelin-1 to induce severe reductions in cerebral blood flow and ischaemic neuronal damage was assessed in anaesthetised rats. Endothelin-1 (25 microliters of 10(-7)-10(-4) M) was applied to the adventitial surface of an exposed middle cerebral artery and striatal blood flow assessed by the hydrogen clearance technique. Endothelin-1 induced severe dose-dependent reductions in cerebral blood flow (e.g., minimum CBF at 10(-5) M of 9 +/- 11 ml 100 g-1 min-1 compared to 104 +/- 22 ml 100 g-1 min-1 with vehicle, p < 0.05), which persisted for at least 60 min at each concentration of endothelin-1. Application of endothelin-1 to the middle cerebral artery produced dose-dependent ischaemic brain damage (e.g., volume of damage of 65 +/- 34 mm3 at 10(-5) M compared to 0.22 +/- 0.57 mm3 for vehicle, p < 0.01). These data demonstrate that endothelin-1 is capable of reducing blood flow to pathologically low levels and provide a new model of controlled focal ischaemia followed by reperfusion.

Animals↗
PubMed1993

Parental costs of neonatal visiting.

Interviews with 93 mothers of 109 low birthweight infants admitted to a regional neonatal intensive care unit showed that, although 82 (88%) mothers visited on a daily basis, some families faced considerable travelling difficulties. Five families travelled more than 100 miles and three families had twin siblings in different neonatal units. Analysis of the travelling and associated expenditure strongly indicates that the parents in most need received little or no help from the statutory authorities and only 26 (28%) families received financial help from any source. There emerges a strong case for offering appropriate financial help to parents on low incomes to facilitate visiting and increase family contact.

Costs and Cost Analysis↗
PubMed1993

Gastric syphilis. Primary diagnosis by gastric biopsy: report of four cases.

Gastric involvement in secondary or tertiary syphilis is rarely recognized clinically, and its diagnosis by examination of endoscopic biopsy specimens has been reported infrequently. We report four cases of gastric syphilis with the primary diagnosis made by gastric biopsy. The patients, all male, ranged in age from 38 to 78 years and presented with gastric complaints, the most common being upper gastrointestinal tract bleeding (three of four). Gastroscopy showed either erosive gastritis or gastric ulcers with heaped, nodular edges. The clinical diagnoses ranged from benign ulcer disease to infiltrating carcinoma and lymphoma. Gastric biopsy specimens in all cases showed a severe gastritis with dense plasmacytic infiltration, associated with varying numbers of polymorphonuclear leukocytes and lymphocytes, variable degrees of glandular destruction and reactive atypia, and a vasculitis without proliferative changes. Modified Steiner silver impregnation stain revealed numerous spirochetes in all four cases and associated Helicobacter pylori infection in one case. Serologic studies for syphilis were positive in all four cases (rapid plasma reagin test, fluorescent treponemal antibody absorption test). None of the patients were seroreactive for antibodies to human immunodeficiency virus. These recent cases of gastric syphilis emphasize the importance of remaining alert to the protean clinical manifestations of syphilis and aware of the histopathologic patterns of this disease.

Adult↗
PubMed1992

Fungal keratitis from nylon line lawn trimmers.

Ocular trauma from nylon line lawn trimmers is becoming more prevalent. Previous case reports have described penetrating trauma caused by these tools. We managed three cases of fungal keratitis caused by injuries from nylon line trimmers. Fungal keratitis should be strongly considered as the cause of any corneal ulcer related to trauma from a nylon line lawn trimmer.

Accidents, Home↗
PubMed1992

Autoradiographic evaluation of forskolin and D1 dopamine receptor binding in a rat model of focal cerebral ischaemia.

Post-ischaemic changes in forskolin and D1 dopamine receptor (labelled with SCH23390) binding sites were evaluated in a rat unilateral middle cerebral artery occlusion (MCA) model. The changes in binding were assessed acutely (2 h post-MCA occlusion) in relation to local cerebral blood flow (lCBF) and chronically (24 h post-MCA occlusion) in relation to histopathological alterations. Two hours following occlusion lCBF was significantly reduced throughout the territory of the MCA. Despite the widespread hypoperfusion, significant reductions in binding were only observed in the dorsolateral caudate nucleus--the region with the most profound reduction in blood flow (6% of the control contralateral lCBF value). Forskolin binding sites were reduced to 40% of the contralateral value while D1 binding sites were reduced to 80% of the contralateral value. Analysis of the relationship between forskolin binding and CBF in the caudate nucleus revealed that the ischaemic threshold for alteration in forskolin binding sites 2 h after MCA occlusion was approximately 34 ml/100 g/min. Twenty-four h post-occlusion forskolin binding sites were further reduced in the dorsolateral caudate nucleus (to 6% of contralateral) while D1 binding showed minimal reduction from that observed at 2 h. The areas of reduced binding corresponded to the area of histopathological change in the caudate nucleus and rostral neocortex. In conclusion, reduction in forskolin binding progresses further than reduction in D1 binding within the first 24 h following focal cerebral ischaemia. For both forskolin and D1 binding sites, the areas of reduced binding 24 h post-MCA occlusion predicted the area of histopathological change.

Animals↗
PubMed1992

Effects of novel fluoroquinolones on the catalytic activities of eukaryotic topoisomerase II: Influence of the C-8 fluorine group.

A previous study (M.J. Robinson, B.A. Martin, T.D. Gootz, P.R. McGuirk, M. Moynihan, J.A. Sutcliffe, and N. Osheroff, J. Biol. Chem. 266:14585-14592, 1991) demonstrated that novel 6,8-difluoroquinolones were potent effectors of eukaryotic topoisomerase II. To determine the contribution of the C-8 fluorine to drug potency, we compared the effects of CP-115,955 [6-fluoro-7-(4-hydroxyphenyl)-1-cyclopropyl-4-quinolone-3-carboxylic acid] on the enzymatic activities of Drosophila melanogaster topoisomerase II with those of CP-115,953 (the 6,8-difluoro parent compound of CP-115,955). Removal of the C-8 fluoro group decreased the ability of the quinolone to enhance enzyme-mediated DNA cleavage approximately 2.5-fold. Like its difluorinated counterpart, CP-115,955 increased the levels of cleavage intermediates without impairing the DNA religation reaction of the enzyme. Removal of the C-8 fluorine reduced the ability of the quinolone to inhibit topoisomerase II-catalyzed DNA relaxation. In addition, the cytotoxicity of CP-115,955 towards Chinese hamster ovary cells was decreased compared with that of CP-115,953. These results demonstrate that the C-8 fluorine increases the potency of quinolone derivatives against eukaryotic topoisomerase II and mammalian cells. Further comparisons of CP-115,955 with CP-115,953 and CP-67,804 (the N-1 ethyl-substituted derivative of the difluoro parent compound) indicate that the two intrinsic activities of quinolone-based drugs towards topoisomerase II (i.e., enhancement of DNA cleavage and inhibition of catalytic strand passage) can be differentially influenced by alteration of ring substituents. Finally, correlations between the biochemical and cytological activities of these drugs suggest that the ability to inhibit catalytic strand passage enhances the cytotoxic potential of quinolones towards eukaryotic cells.

Animals↗
PubMed1992

When will my baby go home?

The length of stay of preterm babies discharged from a neonatal nursery was determined and the predictive value of perinatal factors on the duration of stay was assessed on 762 preterm Salford born babies admitted to Hope Hospital neonatal unit between April 1986 and November 1990. The data were analysed using multiple logistical regression and forward stepwise regression analysis. Babies were discharged at a median (quartile range) postconceptional age of 36.3 (35.3-37.6) weeks. Seventeen factors were found to be strongly predictive of discharge date. The most significant predictive factor was gestational age accounting for 40% of variability compared with respiratory difficulties (6%), low birth weight (4%), sepsis (2%), and metabolic problems (1%). Most babies are discharged at approximately the same postconceptional age despite variations in their clinical course. Gestational age at birth is the most powerful predictive factor of time of discharge.

Bacterial Infections↗