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Biomedical subjects

C Adams

Publications and source records attributed to C Adams.

At least 91 records · Page 5Linked to original sources
PubMed1996

Interaction between nutrition and Eimeria acervulina infection in broiler chickens: development of an experimental infection model.

In three experiments broiler chickens were inoculated with sporulated Eimeria acervulina oocysts at 18 d of age. Feed intake, body-weight gain, brush-border enzyme activities, fat digestion, protein digestion and protein retention were measured. Body-weight gain was reduced during the acute phase of the infection and increased during the recovery phase of the infection. Feed intake was decreased on day 4 and day 5 postinfection (PI) and increased from day 7 to day 11 PI. Maltase (EC 3.2.1.20) and sucrase (EC 3.2.1.48) activities were decreased on day 5 PI in all intestinal segments. In Expts 2 and 3, however, maltase activity was increased in the ileum. Fat digestion was decreased from day 2 to day 11 PI. N digestion and retention were decreased from day 2 to day 11 PI.

Animal Nutritional Physiological Phenomena↗
PubMed1996

Interaction between nutrition and Eimeria acervulina infection in broiler chickens: diet compositions that improve fat digestion during Eimeria acervulina infection.

Previously an experimental infection model was developed in which broiler chickens were inoculated with sporulated Eimeria acervulina oocysts at an age of 18 d. The infection resulted in adverse performance results and reduced nutrient digestion. In two new experiments with the infection model effects of diet adjustments on fat digestion were investigated. In the first experiment addition of 0.4 g cholic acid/kg to a diet rich in animal fat resulted in increased fat digestion during the infection. In the second experiment replacing animal fat by coconut oil resulted in improved fat digestion during the coccidiosis infection. However, replacement of animal fat by soybean oil did not improve fat digestion.

Animal Nutritional Physiological Phenomena↗
PubMed1996

Nicotinic receptor function in schizophrenia.

Schizophrenia can be partially characterized by deficits in sensory processing. Biochemical, molecular, and genetic studies of one such endophenotype, the P50 auditory-evoked potential gating deficit, suggest that one of the neuronal nicotinic receptors, the alpha 7 nicotinic receptor, may function in an inhibitory neuronal pathway involved in this phenotype. The P50 deficit is normalized in nongating subjects by nicotine. Although most schizophrenia patients are heavy smokers, the effects of nicotine may be transient, as alpha 7 receptors are known to desensitize rapidly. In an animal model of the P50 gating deficit, antagonists of the alpha 7 nicotinic receptor block normal gating of the second of paired auditory stimuli. Regional localization of receptor expression includes areas known to function in sensory filtering. An inhibitory mechanism, in the hippocampus, may involve nicotinic stimulation of gamma-aminobutyric acid (GABA)ergic interneurons, resulting in decreased response to repetitive stimuli. Expression of the alpha 7 receptor is decreased in hippocampal brain tissue, dissected postmortem, from schizophrenia subjects. The P50 deficit is inherited in schizophrenia pedigrees, but it is not sufficient for disease development and thus represents a predisposition factor. Linkage analysis between the P50 deficit in multiplex schizophrenia pedigrees and deoxyribonucleic acid (DNA) markers throughout the genome yielded positive lod scores to DNA markers mapping to a region of chromosome 15 containing the alpha 7 nicotinic receptor gene. Elucidation of possible interactions of the P50 with other factors, known to be important in the etiology of the disease, is important in determining an overall pathobiology of schizophrenia.

Animals↗
PubMed1996

Contralateral cerebellar hemorrhagic infarction after pterional craniotomy: report of five cases and review of the literature.

OBJECTIVE AND IMPORTANCE: Five cases of cerebellar hemorrhagic infarction complicating pterional craniotomy are presented. Recognition of this rare complication may be delayed, with catastrophic consequences, because clinicians are unaware of the possibility. We suggest that the mechanism of this complication is dislocation of the dependent part of the cerebellum and venous obstruction causing hemorrhagic infarction. CLINICAL PRESENTATION: Five patients undergoing pterional craniotomies for benign conditions (four unruptured aneurysms and one meningioma) developed hemorrhagic infarction of the contralateral cerebellum in the postoperative period. This resulted in obstructive hydrocephalus and brain stem compression. A review of the literature revealed only one previous report of a similar complication in patients with gross coagulopathy. This was not a problem in our patients. INTERVENTION: The time of onset of symptoms varied from immediately postoperative to 24 hours later. Once the diagnosis was made, the hydrocephalus was drained and the posterior fossa was decompressed. CONCLUSION: The outcome depended on two variables: 1) the rate of development of hemorrhagic infarction and the associated complications and 2) the amount of time that elapsed before remedial action was taken. Two patients with the first signs of deterioration in the immediate postoperative period had the worst outcome; one died and the other remained severely disabled. In two patients with good neurological recovery, problems were identified and corrected within 4 hours of the first sign of deterioration. Rapid overdrainage of cerebrospinal fluid during supratentorial surgery should be avoided, and the fluid volume should be replaced before closure. Postoperative evaluation of patients whose conditions deteriorate after supratentorial craniotomy should include adequate imaging studies of the posterior fossa.

Cerebellar Diseases↗
PubMed1996

Elevated aminotransferase activity as an indication of muscular dystrophy: case reports and review of the literature.

Five male children are reported in whom incidental recognition of elevated serum alanine aminotransferase (ALT) activity initiated investigation to identity the cause of suspected hepatocellular injury. All five were later diagnosed with X chromosome-linked muscular dystrophy. The serum level of ALT, generally considered to be specific for hepatocellular injury, was increased two to 25 times above normal in all the reported cases. Paradoxically, the increase in ALT activity was greater than that of serum aspartate aminotransferase (three to 16 times normal), an enzyme whose elevation is generally recognized as being less specific and indicative of muscle, cardiac, kidney, pancreatic, red blood cell or hepatic injury. At presentation to the gastrointestinal service, one case, age 2.5 months, had no symptoms or signs of neuromuscular dysfunction, while the other four had previously unrecognized hypertrophy of the calves, proximal limb weakness, positive Gower's sign or delayed gross motor skills. All five patients had marked elevation of serum creatine kinase activity and histopathologically confirmed muscular dystrophy. The practical clinical implication of this report is that children with elevated serum ALT, in the absence of other signs and symptoms of hepatic injury, may have occult muscular disease--most frequently muscular dystrophy. Although the clinical signs of muscular dystrophy may be subtle or absent, early determination of creatine kinase will suggest the correct diagnosis and minimize extensive and invasive investigation focusing on hepatic injury.

Adolescent↗
PubMed1996

Dynamic contrast-enhanced MR imaging of perianal fistulas.

OBJECTIVE: The objective of this study was to prospectively compare dynamic contrast-enhanced MR imaging with MR sequences previously described for assessing perianal fistulas in order to determine the best MR protocol for their evaluation. SUBJECTS AND METHODS: MR examinations of 42 consecutive patients with clinically suspected perianal fistulas were independently evaluated by two experienced observers blinded to the findings of digital rectal examination. The observers' evaluations occurred before definitive surgical exploration. All patients had body-coil MR imaging examinations, including the following sequences that were ranked for anatomic and pathologic information: spin-echo T1-weighted, short inversion time inversion recovery, and dynamic contrast-enhanced MR imaging in the coronal plane; and spin-echo T2-weighted imaging in the axial plane. Surgical findings were accepted as the gold standard and were recorded independently by the surgeon, who was unaware of the findings of the MR assessment. MR findings were subsequently correlated with digital rectal examination before surgery and with clinical follow-up. RESULTS: MR imaging correctly allowed our blinded observers to predict the surgical anatomy of perianal disease in 37 of the 42 patients (accuracy, 88%). For detection of the presence and site of an enteric fistulous entry, MR imaging had a sensitivity of 97%, a specificity of 67%, a positive predictive value of 88%, and a negative predictive value of 89%. On MR imaging examination, eight patients had no fistula, 12 had simple intersphincteric fistulas, and 22 had complex fistulas. MR imaging revealed all 14 perianal abscesses and fluid collections found at surgery. Digital rectal examination before surgery failed to reveal abscesses or important secondary tracks in eight of the 22 complex fistulas. For anatomic and pathologic depiction of fistulas, dynamic contrast-enhanced MR imaging ranked as the best sequence for 22 of 34 fistulas. The short inversion time inversion recovery sequence, which was unable to distinguish small abscesses from perianal inflammation and showed spurious high signal in old fibrotic tracks, led our observers to misdiagnose five cases. In four patients for which initial surgery did not confirm enteric entry sites that our observers had predicted by MR imaging, follow-up has confirmed the observers' diagnoses. The observers' evaluations of the MR examinations agreed in 37 (88%) of the 42 cases. CONCLUSION: MR imaging is more accurate than digital rectal examination before surgery in detecting complex features of perianal fistulas. MR imaging is noninvasive, is highly accurate, and has low interobserver variability. With MR imaging, observers may better predict outcome than with initial surgical exploration. MR assessment that includes dynamic contrast-enhanced MR imaging and axial T2-weighted sequences (examination time, 20 min) provides the anatomic and pathologic information required to guide surgical management.

Adult↗
PubMed1996

Genetic variability in the tumor necrosis factor-lymphotoxin region influences susceptibility to rheumatoid arthritis.

The major histocompatibility complex class III tumor necrosis factor-lymphotoxin (TNF-LT) region (6p21.3) was investigated as a possible susceptibility locus for rheumatoid arthritis (RA). Inheritance of five TNF microsatellite markers was determined in 50 multiplex families. Overall, 47 different haplotypes were observed. One of these, the TNF a6, b5, c1, d3, e3 (H1) haplotype, was present in 35.3% of affected, but in only 20.5% of unaffected, individuals (P < .005). This haplotype accounted for 21.5% of the parental haplotypes transmitted to affected offspring and only 7.3% not transmitted to affected offspring (P = .0003). The TNF a6 and TNF c1 alleles were individually associated with RA (P = .0005 and .0008, respectively), as were the HLA-DRB1 "shared epitope" (SE) (P = .0001) and HLA-DRB1*0401 (P = .0018). Both univariate and bivariate conditional logistic regression analysis showed significant effects of TNF c1 and SE in increasing risk to RA (P < .001). Stratification by the presence of SE indicated an independent effect of the TNFc1 allele (P = .0003) and the HLA A1, B8, DR3 extended haplotype (always TNFa2, b3, c1, d1, e3) (P = .0027) in SE heterozygotes, while the H1 haplotype was associated with RA in SE homozygotes (P = .0018). The TNF-LT region appears to influence susceptibility to RA, distinct from HLA-DR.

Arthritis, Rheumatoid↗
PubMed1995

Non-linkage of a T-cell receptor gamma chain microsatellite (D7S485) to rheumatoid arthritis in multiplex families.

A highly informative microsatellite marker, D7S485, from the T-cell receptor gamma (TCRG) locus, has been used to study segregation of TCRG genes in 26 multiplex rheumatoid arthritis (RA) families. We used the sib-pair method to assess excess identity-by-descent sharing among affected members in these families and the LINKAGE package of programs was used to calculate two-point lod scores for the D7S485 marker. There was no evidence for segregation of TCRG genes with RA in affected siblings and significantly negative lod scores were obtained from linkage analyses using both autosomal dominant and recessive models of inheritance.

Adolescent↗
PubMed1995

Long-term effects of human-to-rat mesencephalic xenografts on rotational behavior, striatal dopamine receptor binding, and mRNA levels.

Fetal ventral mesencephalic grafts have been used as a tool to counteract the symptoms of Parkinson's disease. In this study human fetal ventral mesencephalic xenografts were implanted into the lateral ventricle of unilaterally dopamine-depleted immunosuppressed rats. Rotational behavior elicited by low doses of apomorphine, host striatal dopamine receptor binding, and mRNA levels were investigated. Rotational behavior was reduced beginning 2 months after grafting. After 4 months only a small number of rotations, lasting approximately 30 min, were recorded. Seven months after transplantation, the rotational behavior was completely eleminated. Dopamine D2 receptor binding revealed significantly increased levels in sham-operated 6-hydroxydopamine- (6-OHDA) lesioned control striata. These increased levels decreased, and although still significantly higher at 4 months, normalized at the survival time of 7 months postgrafting. Regional differences were still obvious at 7 months in the dorsolateral quadrant of dorsal striatum. Dopamine D2 receptor mRNA revealed significantly increased levels in the lateral aspects of 6-OHDA-lesioned control striata, reversing by 4 months postgrafting. The D1 receptor binding revealed a moderately reduced signal in striata of lesioned animals. After grafting, this reduction became significantly lower than that seen in the control side, with a continous decrease over time. The same pattern was detected using in situ hybridization for dopamine D1 receptor mRNA, that is, moderate decreases after dopamine depletion and a significant decrease in the dorsomedial part of dorsal striatum 7 months postgrafting. Dopamine D3 receptor binding was increased after dopamine depletion, but reversed already by 4 months postgrafting. Taken together, human ventral mesencephalic xenografts are able to completely reverse apomorphine-induced rotational behavior, provided the grafts are left in vivo for a sufficient time. The increased striatal D2 receptors are reversed after grafting, but the human xenograft further suppressed the D1 receptor subtype both at binding and at mRNA levels. There was no strict correlation in the time courses of dopamine receptor changes and reduction of rotational behavior.

Animals↗
PubMed1995

Neuromuscular complications of bone marrow transplantation.

Six children are reported with neuromuscular complications of allogenic bone marrow transplantation. Myositis occurred in 4, chronic inflammatory demyelinating neuropathy in 1, and myasthenia gravis in 1. Chronic graft-versus-host disease was present in 3. The onset following bone marrow transplant may be delayed.

Biopsy↗
PubMed1994

Influence of the chemical nature of side chain at beta 108 of hemoglobin A on the modulation of the oxygen affinity by chloride ions. Low oxygen affinity variants of human hemoglobin expressed in transgenic pigs: hemoglobins Presbyterian and Yoshizuka.

Hemoglobin A (HbA) and two low oxygen affinity variants of HbA, HbPresbyterian and HbYoshizuka, were produced in transgenic pigs and purified to homogeneity by ion-exchange chromatography. These two variants contain either lysine (HbPresbyterian) or aspartic acid (HbYoshizuka) instead of the normal asparagine residue at position beta 108 in HbA. Transgenic pigs expressed these variants at a level up to 11% and were healthy. Both HbPresbyterian and HbYoshizuka exhibited low O2 affinity (P50 of 21.2 and 18.9, respectively, compared with control HbA value of 11.8 in 0.1 M NaCl, pH 7.5) and retained normal cooperativity with Hill coefficients of 2.9 and 2.5, respectively. HbPresbyterian exhibited Bohr effect comparable with HbA. In contrast, HbYoshizuka had a diminished response to changes in pH. Thus the structural basis of reduced O2 affinity of these variants appears to be distinct: the consequence of mutation at beta 108 is a function of the chemical nature of the side chain. This is further confirmed by the sensitivity of the O2 affinity of the variants to the presence of Cl-. The O2 affinity of HbYoshizuka is insensitive to changes in Cl- concentration, whereas the O2 affinity of HbPresbyterian exhibited a pronounced and dramatic chloride effect. In fact, P50 of HbPresbyterian was identical to that of HbA at very low Cl- concentrations, and the P50 increased to >40 at 0.5 M Cl-. The chloride effect was completely abolished when HbPresbyterian was stabilized at the 2,3-diphosphoglycerate pocket by interdimeric cross-linking. Molecular modeling studies demonstrate that in HbPresbyterian, Cl- can bridge the epsilon-amino group of Lys beta 108 with either the guanidino group of Arg beta 104 or the epsilon-amino group of Lys alpha 99, resulting in the stabilization of the "T" structure. The utility of these low O2 affinity hemoglobins as cell-free oxygen carriers is discussed.

Allosteric Regulation↗
PubMed1994

Isolation of a gene (pbsC) required for siderophore biosynthesis in fluorescent Pseudomonas sp. strain M114.

An iron-regulated gene, pbsC, required for siderophore production in fluorescent Pseudomonas sp. strain M114 has been identified. A kanamycin-resistance cassette was inserted at specific restriction sites within a 7 kb genomic fragment of M114 DNA and by marker exchange two siderophore-negative mutants, designated M1 and M2, were isolated. The nucleotide sequence of approximately 4 kb of the region flanking the insertion sites was determined and a large open reading frame (ORF) extending for 2409 bp was identified. This gene was designated pbsC (pseudobactin synthesis C) and its putative protein product termed PbsC. PbsC was found to be homologous to a family of enzymes involved in the biosynthesis of secondary metabolites, including EntF of Escherichia coli. These enzymes are believed to act via ATP-dependent binding of AMP to their substrate. Several areas of high sequence homology between these proteins and PbsC were observed, including a conserved AMP-binding domain. The expression of pbsC is iron-regulated as revealed when a DNA fragment containing the upstream region was cloned in a promoter probe vector and conjugated into the wild-type strain, M114. The nucleotide sequence upstream of the putative translational start site contains a region homologous to previously defined -16 to -25 sequences of iron-regulated genes but did not contain an iron-box consensus sequence. It was noted that inactivation of the pbsC gene also affected other iron-regulated phenotypes of Pseudomonas M114.

Amino Acid Sequence↗
PubMed1994

The tryptophan repressor sequence is highly conserved among the Enterobacteriaceae.

Tryptophan biosynthesis in Escherichia coli is regulated by the product of the trpR gene, the tryptophan (Trp) repressor. Trp aporepressor binds the corepressor, L-tryptophan, to form a holorepressor complex, which binds trp operator DNA tightly, and inhibits transcription of the tryptophan biosynthetic operon. The conservation of trp operator sequences among enteric Gram-negative bacteria suggests that trpR genes from other bacterial species can be cloned by complementation in E. coli. To clone trpR homologues, a deletion of the E. coli trpR gene, delta trpR504, was made on a plasmid by site-directed mutagenesis, then crossed onto the E. coli genome. Plasmid clones of the trpR genes of Enterobacter aerogenes and Enterobacter cloacae were isolated by complementation of the delta trpR504 allele, scored as the ability to repress beta-galactosidase synthesis from a prophage-borne trpE-lacZ gene fusion. The predicted amino acid sequences of four enteric TrpR proteins show differences, clustered on the backside of the folded repressor, opposite the DNA-binding helix-turn-helix substructures. These differences are predicted to have little effect on the interactions of the aporepressor with tryptophan, holorepressor with operator DNA, or tandemly bound holorepressor dimers with one another. Although there is some variation observed at the dimer interface, interactions predicted to stabilize the interface are conserved. The phylogenetic relationships revealed by the TrpR amino acid sequence alignment agree with the results of others.

Amino Acid Sequence↗
PubMed1994

Anatomical urinary stress incontinence in women with rheumatoid arthritis: its frequency and coping strategies.

OBJECTIVE: The objectives of this study were to develop a valid screening tool for anatomical urinary stress incontinence (AUSI), to use it to determine the frequency of AUSI in women with RA, and to identify the cognitive, behavioral, and psychological coping strategies used by these women to deal with incontinence. METHODS: A screening tool concerning AUSI was validated by comparing self-reported incidences of AUSI with clinical evaluation. Questionnaires regarding presence of AUSI and cognitive, behavioral, and psychological coping strategies were sent to 750 women clinically diagnosed with RA. RESULTS: Of the 262 respondents (35% response rate), 21% had characteristics of AUSI, a rate similar to general population studies. Coping strategies varied depending on whether the women were at home or away from home and whether the women were alone or with others. CONCLUSIONS: There is a need for women with incontinence and the health care workers who serve them to be educated about AUSI and its treatments.

Adaptation, Psychological↗
PubMed1994

Primary hypothyroidism with intracranial hypertension and pituitary hyperplasia.

A 12-year-old girl presented with primary hypothyroidism, secondary pituitary hyperplasia, and intracranial hypertension. Cranial computed tomography revealed a sellar mass with suprasellar extension. She responded to medical treatment. Intracranial hypertension may be associated with primary hypothyroidism prior to thyroxine treatment. Because significant pituitary hyperplasia can be associated with primary hypothyroidism, it is vital to have endocrine investigation prior to consideration of surgical removal of an apparent pituitary tumor.

Cerebrospinal Fluid Pressure↗
PubMed1994

Autosomal recessive, fatal infantile hypertonic muscular dystrophy among Canadian Natives.

We describe eleven mid-western Canadian aboriginal infants with a unique, progressive muscle disorder. All except one had muscle biopsy and/or autopsy. The infants were normal newborns who rapidly developed rigidity of all skeletal muscles, with early, respiratory insufficiency. Death occurred before 18 months of age. Electromyography showed increased insertion activity and profuse fibrillation potentials; motor unit potentials and interference pattern are normal until late in the course. Pathologic features include progressive, granular to powdery Z-band transformation, myofibrillar loss, and muscle regeneration. SDS-gel electrophoresis of one muscle sample revealed increased 54kDa and reduced 80kDa protein fractions. This disease differs from other conditions with Z-band alterations because of continuous muscle activity and relentless clinical progression. The clinical features, elevated serum creatine kinase, electromyographic and muscle biopsy findings suggest a dystrophic process. The recognition of this condition as an autosomal recessive disorder allows appropriate genetic counselling.

Canada↗