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Biomedical subjects

M C Roberts

Publications and source records attributed to M C Roberts.

At least 55 records · Page 3Linked to original sources

Depressive and anxiety symptoms in patients with schizophrenia and schizophreniform disorder.

BACKGROUND: Symptoms of depression and anxiety are frequently encountered in the course of schizophrenia and are of considerable clinical importance. They may compromise social and vocational functioning, and they are associated with an increased risk of relapse and suicide. Various treatment approaches have been reported to be successful. METHOD: The sample comprised 177 patients with DSM-III-R or DSM-IV schizophrenia or schizophreniform disorder who were participants in multinational clinical drug trials at our academic psychiatric unit over a 7-year period and who were assessed by means of the Positive and Negative Syndrome Scale (PANSS). Analysis was performed on baseline PANSS scores. The depression/anxiety score was compared in the men and women, first-episode and multiple-episode patients, and those with predominantly positive and negative syndromes. Correlations were sought between depression/anxiety scores and age, total PANSS score, positive score, negative score, general psychopathology score, and treatment outcome. Multivariate analysis was applied to determine contributions of individual variables toward depression/anxiety and outcome scores. RESULTS: Depression and anxiety symptoms were more severe in women (p = .007), first-episode patients (p = .02), and those with predominantly positive symptoms (p < .0001). Depression/anxiety scores were significantly correlated to age (r = -0.31, p < .0001), PANSS positive scores (r = 0.39, p < .0001), and treatment outcome (r = 0.25, p = .006). Multivariate analysis bore out these results, with the exception that first episode was not a significant predictor of depression and anxiety scores. CONCLUSION: PANSS depressive/anxiety scores were generally low in our sample, perhaps because patients with schizoaffective disorder were excluded. The finding that these symptoms were more prominent in women and first-episode patients is in keeping with previous literature. The higher scores in first-episode patients are likely due to the higher positive symptom scores in these patients. The association between depressive/anxiety scores and positive symptoms but not with negative symptoms points to a specific relationship between affective symptoms and the positive symptom domain of schizophrenia. The presence of depressive and anxiety symptoms may predict a more favorable outcome to treatment, although this may only apply to the acute exacerbations of the illness.

Adult↗

Glutamine and transforming growth factor-alpha stimulate extracellular regulated kinases and enhance recovery of villous surface area in porcine ischemic-injured intestine.

BACKGROUND: Epidermal growth factor (EGF) signals enterocyte proliferation via extracellular regulated kinases (ERKs). Because glutamine is required for EGF-stimulated proliferation and stimulates ERKs in intestinal cell culture, we hypothesized that glutamine and the EGF-related peptide transforming growth factor-alpha (TGF-alpha) would synergistically enhance repair associated with stimulation of ERKs. METHODS: Thiry-Vella loops were created in juvenile pigs. One half of the loop was subjected to 2 hours of ischemia, and the other half served as control. Loops were infused daily with Ringer's solution containing 140 mmol/L glucose, 140 mmol/L glutamine, 140 mmol/L glucose plus 60 micrograms/L TGF-alpha, or 140 mmol/L glutamine plus 60 micrograms/L TGF-alpha. RESULTS: After 2 hours of ischemia, complete villous epithelial sloughing was present. By 18 hours, villous epithelium had fully restituted, but villi remained stunted until 144 hours after injury. Glutamine + TGF-alpha triggered sustained increases in ERK activity compared with glucose-treated tissues (maximal at 18 hours), whereas glutamine alone or glucose + TGF-alpha caused only transient elevations in ERK activity. By 72 hours, villous surface area had increased to normal values with glutamine plus TGF-alpha treatment, whereas villi remained stunted with glucose alone, glutamine alone, or glucose plus TGF-alpha. CONCLUSIONS: Glutamine plus TGF-alpha treatment restored mucosal architecture within 72 hours of severe ischemic injury associated with sustained elevations in ERK activity.

Animals↗

Myeloperoxidase activity of the large intestine in an equine model of acute colitis.

OBJECTIVE: To determine whether quantification of myeloperoxidase (MPO) activity could be a useful laboratory technique to detect granulocyte infiltration in equine intestinal tissues. SAMPLE POPULATION: Intestinal tissue (inflamed or healthy) collected from 16 age- and sex-matched Shetland Ponies. PROCEDURE: Intestinal tissue MPO activity was determined, and histologic assessment of adjacent specimens from healthy and inflamed intestine was done. RESULTS: Intestinal tissue MPO activity and histopathologic score increased with time after castor oil challenge and peaked at 16 hours in an equine diarrhea model in which individual ponies provided their own control tissues. CONCLUSIONS: Intestinal tissue inflammation scores correlated positively with tissue MPO activity in adjacent specimens. CLINICAL RELEVANCE: Tissue MPO assay may be a useful laboratory tool to quantify intestinal mucosal inflammation in ponies.

Animals↗

Tetracycline resistance in Staphylococcus spp. from domestic animals.

A total of 838 staphylococcal isolates representing 19 different species were obtained from cattle, cats, dogs, ducks, guinea pigs, horses, mink, pigeons, pigs, rabbits, and turkeys. From these 228 (27.2%) isolates were shown to be resistant to tetracycline and to carry one or two of the tetracycline resistance (tet) genes tet (K), tet (L), tet (M), or tet (O) with seven different distribution patterns. Additional resistances to one or more antibiotics were observed in 153 (67.1%) of the tetracycline resistant isolates. The tet (M) gene was found in 94.3% of the resistant S. intermedius isolates while the tet (K) gene predominated in most of the other staphylococcal species irrespective of the host animal. The tet (K) and tet (L) genes were located on plasmids while the tet (M) and tet (O) genes appeared to be associated with the chromosome.

Animals↗

Antibiotic resistance mechanisms in bacteria of oral and upper respiratory origin.

Over the past 20 years, antibiotic resistance has increased in virtually every species of bacteria examined. In this paper, the main mechanisms of antibiotic resistance currently known for antibiotics used for treatment of disease caused by oral and upper respiratory bacteria will be reviewed, with an emphasis on the most commonly used antibiotics. The possible role that mercury, which is released from silver amalgams, plays in the oral/respiratory bacterial ecology is also discussed, as it relates to possible selection of antibiotic resistant bacteria.

Bacteria↗

Intercity spread of gonococci with decreased susceptibility to fluoroquinolones: a unique focus in the United States.

Patients and gonococcal isolates (n = 783) from five sexually transmitted disease clinics in Ohio and western Pennsylvania were studied to investigate the spread of gonococci with decreased fluoroquinolone susceptibility. Among patients with gonorrhea, rates of infection with strains with decreased fluoroquinolone susceptibility (MIC of 0.125-0.25 microg ciprofloxacin/mL) were 20% for Cleveland, 9% for Akron, 7% for Columbus, 1% for Toledo, and 0.5% for Pittsburgh. Persons infected with strains with decreased susceptibility were more likely than those with susceptible strains to be male and older; no significant differences in sex behaviors, residence of sex partners, or recent antibiotic use were detected. Prevalence of decreased susceptibility was not correlated with reported levels of community fluoroquinolone use. The Pro/IB-3 auxotype/serovar class accounted for 80% (44/55) of isolates with decreased susceptibility. Pro/IB-3 isolates from three cities had indistinguishable pulsed-field gel electrophoresis patterns, suggesting intercity spread of a clone.

Adult↗

The presence of the tetO gene in a variety of tetracycline-resistant Streptococcus pneumoniae serotypes from Washington State.

Seventy tetracycline-resistant Streptococcus pneumoniae were tested for the presence of tetracycline resistance genes, tetM and tetO, using a polymerase chain reaction (PCR) assay and DNA-DNA hybridization. Seven isolates representing five serotypes (12, 22, 6A, 19F and 23) carried the tetO gene. Five of the isolates were genetically unrelated as judged using pulsed field gel electrophoresis (PFGE) analysis. Two 19F isolates came from the same patient, carried both tetM and tetO genes and had the same PFGE pattern. The other 63 isolates carried only the tetM gene. DNA sequences from three of the tetO-carrying isolates were determined; they showed 91-95% nucleotide sequence identity over 300 nucleotides, and 93-95% amino acid sequence identity over 100 amino acids. The isolates carrying both tetO and tetM genes could transfer the tetM gene into both Enterococcus faecalis and S. pneumoniae recipients, but not the tetO gene. There was no detectable transfer of the tetO gene, by conjugation, from the other five isolates.

Adolescent↗

Antimicrobial susceptibilities of Porphyromonas gingivalis, Prevotella intermedia, and Prevotella nigrescens spp. isolated in Spain.

The susceptibilities of 143 Porphyromonas gingivalis, Prevotella intermedia, and Prevotella nigrescens isolates to 18 antimicrobial agents were tested. All P. gingivalis isolates were susceptible. In contrast, some Prevotella spp. (17%) were resistant to beta-lactams, erythromycin, clindamycin, or tetracycline and carried resistance genes, ermF or tetQ, or beta-lactamases.

Adult↗

A novel erythromycin resistance methylase gene (ermTR) in Streptococcus pyogenes.

Erythromycin resistance among streptococci is commonly due to target site modification by an rRNA-methylating enzyme, which results in coresistance to macrolide, lincosamide, and streptogramin B antibiotics (MLSB resistance). Genes belonging to the ermAM (ermB) gene class are the only erythromycin resistance methylase (erm) genes in Streptococcus pyogenes with MLSB resistance that have been sequenced so far. We identified a novel erm gene, designated ermTR, from an erythromycin-resistant clinical strain of S. pyogenes (strain A200) with an inducible type of MLSB resistance. The nucleotide sequence of ermTR is 82.5% identical to ermA, previously found, for example, in Staphylococcus aureus and coagulase-negative staphylococci. Our finding provides the first sequence of an erm gene other than ermAM that mediates MLSB resistance in S. pyogenes.

Amino Acid Sequence↗

Molecular analysis by pulsed-field gel electrophoresis and antibiogram of Streptococcus pneumoniae serotype 6B isolates from selected areas within the United States.

Fifty-eight clinical isolates of Streptococcus pneumoniae serotype 6B, including 16 from Alaska, 14 from Arizona, 11 from Washington, and 17 from seven additional states, were analyzed. The antibiograms of these isolates were assigned to 10 antibiotic profiles based on their susceptibilities to penicillin, erythromycin, tetracycline, and trimethoprim-sulfamethoxazole. Thirty-two (55%) of these isolates were penicillin nonsusceptible, while 21 (36%) were intermediate or resistant to three or more antibiotics. The restriction endonucleases ApaI and SmaI were used to digest intact chromosomes, and the fragments were resolved by pulsed-field gel electrophoresis (PFGE). The ApaI and SmaI PFGE patterns were combined, and 13 of the 16 Alaskan isolates showed indistinguishable PFGE patterns. One other isolate exhibited highly related ApaI and SmaI PFGE patterns, differing by only one band after restriction with ApaI. Among the 14 isolates from Arizona, 1 was indistinguishable from the predominant ApaI and SmaI PFGE patterns seen in the Alaskan isolates; 5 others were highly related (+/-1 band after cutting with either enzyme) to the Alaskan isolates, suggesting a common ancestral origin. Of the remaining eight isolates, six additional ApaI plus SmaI PFGE patterns were observed. The 28 isolates from the various contiguous states had 22 ApaI plus SmaI PFGE patterns. No correlations were found between specific PFGE patterns, antibiograms, dates of isolation, or geography. The serotype 6B isolates across the contiguous United States were genetically diverse, while the 6B isolates from Alaska appeared to be much less diverse.

Alaska↗

Antibiotic resistance in oral/respiratory bacteria.

In the last 20 years, changes in world technology have occurred which have allowed for the rapid transport of people, food, and goods. Unfortunately, antibiotic residues and antibiotic-resistant bacteria have been transported as well. Over the past 20 years, the rise in antibiotic-resistant gene carriage in virtually every species of bacteria, not just oral/respiratory bacteria, has been documented. In this review, the main mechanisms of resistance to the important antibiotics used for treatment of disease caused by oral/respiratory bacteria--including beta-lactams, tetracycline, and metronidazole--are discussed in detail. Mechanisms of resistance for macrolides, lincosamides, streptogramins, trimethoprim, sulfonamides, aminoglycosides, and chloramphenicol are also discussed, along with the possible role that mercury resistance may play in the bacterial ecology.

Drug Resistance, Microbial↗

Prostaglandins I2 and E2 have a synergistic role in rescuing epithelial barrier function in porcine ileum.

Prostaglandins (PG) are cytoprotective for gastrointestinal epithelium, possibly because they enhance mucosal repair. The objective of the present studies was to assess the role of prostaglandins in intestinal repair. Intestinal mucosa from porcine ileum subjected to 1 h of ischemia was mounted in Ussing chambers. Recovery of normal transepithelial electrical resistance occurred within 2 h, and continued to increase for a further 2 h to a value twice that of control. The latter response was blocked by inhibition of prostaglandin synthesis, and restored by addition of both carbacyclin (an analog of PGI2) and PGE2, whereas the addition of each alone had little effect. Histologically, prostaglandins had no effect on epithelial restitution or villous contraction, indicating that elevations in transepithelial resistance were associated with increases in paracellular resistance. Furthermore, prostaglandin-stimulated elevations in resistance were inhibited with cytochalasin D, an agent known to stimulate cytoskeletal contraction. Synergistic elevations in transepithelial resistance, similar to those of carbacyclin and PGE2, were also noted after treatment with cAMP and A23187 (a calcium ionophore). We conclude that PGE2 and PGI2 have a synergistic role in restoration of intestinal barrier function by increasing intracellular cAMP and Ca2+, respectively, which in turn signal cytoskeletal-mediated tight junction closure.

Animals↗

Psychiatric manifestations and magnetic resonance imaging in HIV-negative neurosyphilis.

Neurosyphilis can mimic virtually any psychiatric disorder. Since there are no studies measuring the relationship between its psychiatric manifestations and neuroradiological findings, we performed magnetic resonance imaging (MRI) on 20 newly diagnosed patients with neurosyphilis and 20 healthy volunteers. MRI abnormalities occurred in 13 neurosyphilis patients. These included foci of increased signal intensity of T2-weighted images, and generalized cerebral atrophy. Two control subjects showed minor focal changes. In the neurosyphilis patients, frontal lesions showed statistically significant associations with the overall degree of psychiatric morbidity as measured by the brief psychiatric rating scale (p < 0.05). Temporo-parietal lesions showed a near significant association with cognitive impairment as measured by the Mini mental-state examination (p = 0.06). Atrophy measures correlated significantly with cognitive impairment. The results suggest that the site of brain lesions may be important in determining the nature of the psychiatric symptoms in neurosyphilis.

Adult↗

Is reperfusion injury an important cause of mucosal damage after porcine intestinal ischemia?

BACKGROUND: Intestinal ischemic injury is exacerbated by reperfusion in rodent and feline models because of xanthine oxidase-initiated reactive oxygen metabolite formation and neutrophil infiltration. Studies were conducted to determine the relevance of reperfusion injury in the juvenile pig, whose low levels of xanthine oxidase are similar to those of the human being. METHODS: Ischemia was induced by means of complete mesenteric arterial occlusion, volvulus, or hemorrhagic shock. Injury was assessed by means of histologic examination and measurement of lipid peroxidation. In addition, myeloperoxidase, as a marker of neutrophil infiltration, and xanthine oxidase-xanthine dehydrogenase were measured. RESULTS: Significant ischemic injury was evident after 0.5 to 3 hours of complete mesenteric occlusion or 2 hours of shock or volvulus. In none of these models was the ischemic injury worsened by reperfusion. To maximize superoxide production, pigs were ventilated on 100% O2, but only limited reperfusion injury (1.2-fold increase in histologic grade) was noted. Xanthine oxidase-xanthine dehydrogenase levels were negligible (0.4 +/- 0.4 mU/gm). CONCLUSIONS: Reperfusion injury may not play an important role in intestinal injury under conditions of complete mesenteric ischemia and low-flow states in the pig. This may result from low xanthine oxidase-xanthine dehydrogenase levels, which are similar to those found in the human being.

Animals↗

Probing the nematode surface.

The surface of parasitic nematodes has been well studied with respect to its structural and immunological properties, but little is known about its biophysical nature and the role this plays in the host-parasite relationship. In this article, Clare Roberts and Jay Modha highlight some biophysical features of nematode surfaces and discuss their recent findings regarding mechanisms controlling surface-associated biophysical phenomena observed in parasitic nematodes during infection or culture in medium simulating the mammalian host environment. The nematode surface is distinct from the plasma membrane, nevertheless some parallel features exist and are described.

Journal Article↗