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J A Brown

Publications and source records attributed to J A Brown.

At least 19 recordsLinked to original sources
PubMed1992

A procedure for large-scale purification of domoic acid from toxic blue mussels (Mytilus edulis)

Pure domoic acid is required for use in research to investigate the biological effects of this new shellfish toxin. It may also prove to be a useful tool in studies exploring the basis of Alzheimer's disease. In this paper we describe a procedure which is effective in obtaining adequate quantities of pure domoic acid from blue mussel (Mytilus edulis). The procedure involves tissue homogenization, treatment of homogenate with chloroform and methanol, and separation of different phases with the addition of water. The aqueous-methanolic phase (upper layer) contains water soluble components including domoic acid, the chloroform phase (lower layer) contains lipoid moieties, and the interphase contains denatured proteins. The aqueous phase containing domoic acid was removed, rotory evaporated to get rid of methanol, followed by ultrafiltration to remove high molecular weight contaminants. The filtrate was lyophilized, resuspended in 1 N HCl, centrifuged and the resulting clear solution subjected to column chromatography on C18 reversed phase silica gel. Fractions containing domoic acid were pooled, and lyophilized. A brownish dry powder contained pure domoic acid with 60-65% yield from the original tissue homogenate. Another 10-15% of domoic acid was mixed with its isomer, and can be further resolved to obtain an overall recovery of 75-80% of the starting material.

Animals↗
PubMed1992

Elevated serum alpha-fetoprotein levels in primary gallbladder carcinoma without hepatic involvement.

BACKGROUND: Elevated serum alpha-fetoprotein (AFP) levels, although frequently associated with hepatocellular carcinoma, have also been reported in cases of primary gallbladder carcinoma. METHODS: The case of a 56-year-old man with a markedly elevated serum AFP level and primary gallbladder carcinoma without detectable hepatic involvement is reported. RESULTS: The patient had right upper quadrant abdominal pain and a palpable right upper quadrant mass. Computerized tomography scan of the abdomen showed a large, subhepatic mass consistent with the gallbladder, and normal liver parenchyma. Liver enzyme levels were normal. Management included cholecystectomy followed by postoperative radiation therapy to the gallbladder bed and portal areas and systemic chemotherapy. At the end of therapy, the AFP level had returned to normal. CONCLUSIONS: Gallbladder carcinoma is rarely diagnosed before surgery, which sometimes inhibits operative planning. AFP may be a useful preoperative tumor marker in differentiating the patient with primary gallbladder carcinoma from the patient with gallbladder hydrops.

Adenocarcinoma, Papillary↗
PubMed1992

Parental origin determination in thirty de novo Robertsonian translocations.

Cytogenetic heteromorphisms and restriction fragment length polymorphisms were used to assign the parental origins of 30 de novo non-homologous Robertsonian translocations. The balanced and unbalanced translocations studied included 20 rob(14q21q) four rob(13q14q)four rob(15q21q) one rob(13q15q), and one rob(13q21q). Significantly more maternally (26/30) than paternally (4/30) derived de novo translocations were noted and all rob(14q21q) ascertained through unbalanced probands (20/20) were maternal in origin. Interestingly, 12/13 probands who were trisomic and informative for proximal chromosome 21q loci were homozygous for the markers tested. Segregation (2:1) of the Robertsonian translocation into one daughter cell in meiosis I and subsequent failure of the chromosome 21 chromatids to separate in meiosis II may account for our observation of homozygosity for proximal chromosome 21 loci in the majority of de novo rearrangements tested.

Chromosomes, Human, Pair 21↗
PubMed1992

Glomerular bypass shunts and distribution of glomeruli in the kidney of the lesser spotted dogfish, Scyliorhinus caniculus.

Scanning electron microscopy of corroded resin casts of the renal vasculature of Scyliorhinus caniculus has revealed a novel vascular pathway arising from the afferent arteriole and bypassing the glomerulus. This glomerulus bypass shunt occurred in 36% of the glomerular casts examined. The shunt ran to join a peritubular network of capillaries and thereby offers the potential to vary the degree of glomerular perfusion and control the proportion of active glomeruli. In 29% of glomeruli two efferent arterioles drained the capillary knot. Glomeruli were located close to the dorsal margin of the posterior mass of the kidney, and towards the lateral edge of the anterior lobes of the kidney of female dogfish. In male dogfish, glomeruli were evenly distributed through the posterior mass of kidney, while in female dogfish 89% of glomeruli occurred in the posterior mass and 11% of glomeruli were located within the small anterior lobes.

Animals↗
PubMed1992

Angiotensin II binding to tissues of the rainbow trout, Oncorhynchus mykiss, studied by autoradiography.

Tissue slices from seawater-adapted and freshwater-adapted rainbow trout, Oncorhynchus mykiss, were exposed to 125I-angiotensin II (1.01.10(-9) M) and binding sites located by light-microscopic autoradiography. Binding/uptake was significantly inhibited by excess (10(-5) M) unlabelled angiotensin II, suggesting specific binding/uptake of angiotensin II to the ventral and dorsal aorta (smooth muscle), urinary bladder (smooth muscle and epithelial lining), glomeruli and proximal tubules, the gill (lamellae and central filament), skin (epithelium), intestine and oesophagus (mucosal epithelium), liver, heart (ventricular myocytes), adrenocortical tissue and brain (cerebellum and medulla oblongata). The specific binding/uptake of angiotensin II to tissues of freshwater- and seawater-adapted animals were generally similar. However, binding/uptake by the proximal tubules was significantly higher in freshwater-adapted trout than seawater-adapted trout. Specific binding/uptake of angiotensin II by the smooth muscle of the bladder was significantly higher in trout adapted to seawater than trout adapted to freshwater.

Adaptation, Physiological↗
PubMed1992

Sino-bronchial reflex, asthma and sinusitis.

Sinusitis should be suspected in cases of chronic, difficult to control asthma or other pulmonary diseases. Appropriate measures to diagnose and treat sinus disease are listed, and an upright Waters roentgenogram may be all that is required for diagnosis. A true sino-bronchial reflex is proposed in these patients. Nasal receptors and reflexes are effective in the physiology of the nose, and in many cases, the diagnosis and treatment of rhinitis and sinusitis results in the improvement of various chronic pulmonary conditions.

Asthma↗
PubMed1992

Molecular cloning and expression of the rhesus macaque D1 dopamine receptor gene.

Using homologous probes for the cloning of related genes within the family of guanine nucleotide-binding protein-coupled receptors, we have cloned the gene for the rhesus macaque D1 dopamine receptor. By using the rat D1 receptor coding sequence as a probe under high stringency conditions, the rhesus D1 receptor gene was isolated from a lambda EMBL3 rhesus genomic DNA library. The rhesus D1 dopamine receptor gene is intronless and encodes a 446-amino acid protein that contains two consensus sites for asparagine-linked glycosylation (Asn-5 and Asn-176) and two consensus sites for cAMP-dependent protein kinase phosphorylation (Thr-136 and Thr-268). The primary amino acid sequence of the rhesus D1 dopamine receptor shows an extremely high degree of similarity (99.6%) to the human D1 receptor. Genomic DNA analyses conducted with high and reduced stringency hybridizations indicate that the rhesus macaque D1 receptor is a member of a large multigene family. Like the human D1 receptor mRNA, the rhesus D1 receptor mRNA is approximately 4 kilobases in size and is localized predominantly in the caudate, with lesser amounts in the hippocampus and cortex. The rhesus D1 receptor coding region was inserted into the cytomegalovirus promoter-driven expression vector pcDNA-1, and the recombinant (pcDNA-D1) was cotransfected with the selectable marker pRSVneo, conferring G418 resistance, into D1 receptor-deficient C6 glioma cells. Analyses of the selected transfectant demonstrate the expression of a high affinity, functional D1 dopamine receptor. The D1 receptor radioligand [3H]SCH 23390 bound transfectant membranes with an affinity (Kd), of 0.3 nM; the D2-selective ligand spiperone, the dopamine receptor ligand clozapine, and the serotonin receptor antagonist ketanserin bound with considerably lower affinities (102, 80, and 95 nM, respectively). Both dopamine and the D1-selective agonist SKF 38393 inhibited the binding of [3H]SCH 23390 to transfectant cell membranes; the binding of these agonists was sensitive to GTP. Dopamine potently stimulated the accumulation of cAMP in transfected C6 cells, whereas SKF 38393 was a partial agonist in these cells. Also, the density of recombinant D1 receptors on the transfectant cells was decreased 40% upon treatment with 10 microM dopamine, indicating that occupation of recombinant D1 receptors by agonists alters surface expression of the receptors.

Adenylyl Cyclases↗
PubMed1992

What about Prozac?

Explore the source record for details and available documents.

Combined Modality Therapy↗
PubMed1992

The diagnosis and management of depression: an overview.

The authors present an overview of the diagnosis, treatment, and management of depressed patients. They discuss current psychotherapeutic techniques, the psychopharmacologic management of depression, and guidelines for referral of depressed patients to mental health professionals.

Antidepressive Agents, Tricyclic↗
PubMed1992

Aphidicolin-inducible common fragile-site expression: results from a population survey of twins.

Common chromosomal fragile sites appear to be ubiquitous in humans and other mammals, and, although the molecular basis and function of these sites remain an enigma, it has been speculated that they may be a cytogenetic expression of gene activity. A population survey of 28 twin pairs was conducted to assess the heritability of common fragile-site expression. Our data yielded a heritability estimate of .88 for total site expression, suggesting that these sites may result from some common process that is under relatively stringent genetic control. An analysis of the expression of individual autosomal sites revealed that expression on both homologues in the same cell occurred more frequently than expected.

Adolescent↗
PubMed1991

Misoprostol compared with sucralfate in the prevention of nonsteroidal anti-inflammatory drug-induced gastric ulcer. A randomized, controlled trial.

OBJECTIVES: To compare the efficacy and frequency of adverse experiences of misoprostol and sucralfate in the prevention of gastric ulcers in patients receiving nonsteroidal anti-inflammatory drug (NSAID) therapy. DESIGN: A prospective, randomized, single-blind, multicenter trial. PATIENTS: Patients with osteoarthritis receiving treatment with ibuprofen, piroxicam, or naproxen and experiencing abdominal pain were eligible. INTERVENTIONS: Patients who were expected to receive at least 3 months of NSAID therapy and who did not have a gastric ulcer at the time of the initial screening endoscopy were randomized to receive misoprostol, 200 micrograms four times a day, or sucralfate, 1 g four times a day. A gastric ulcer was defined as a lesion of the gastric mucosa 0.3 cm or greater in diameter. Patients were followed clinically, and repeat endoscopies were performed after 4, 8, and 12 weeks. MAIN MEASUREMENT: The development of a gastric ulcer, which was regarded as a prophylaxis failure. RESULTS: Two hundred fifty-three patients were evaluable for efficacy analysis. A gastric ulcer developed in 2 of the 122 (1.6%, 95% CI, 0.3% to 6.4%) patients on misoprostol, compared with 21 of 131 patients on sucralfate (16%, CI, 10.4% to 23.7%). The difference in ulcer rates was 14.4% (CI, 10.4% to 19.5%; P less than 0.001). CONCLUSION: In patients receiving chronic NSAID therapy for osteoarthritis, treatment with misoprostol for 3 months was associated with a significantly lower frequency of gastric ulcer formation, compared with treatment with sucralfate (P less than 0.001).

Adult↗
PubMed1991

Minimization of indomethacin-induced reduction in renal function by misoprostol.

A prospective, randomized, open-label, triple crossover comparison of the effects of indomethacin, misoprostol, or the combination, on renal function was performed to assess the ability of an oral prostaglandin E analogue, misoprostol, to minimize indomethacin-induced decline in renal function in middle-aged women. Twelve healthy women (mean age: 60.5 +/- 1.6 yr) with normal renal function (serum creatinine: 81 +/- 9 umol/L) were studied; six women were normotensive, and six women were hypertensive with their blood pressure controlled with 50-mg hydrochlorothiazide daily. All patients were placed on a 2-g sodium daily diet for 2 weeks before initiation of the study. The subjects were prospectively randomized to receive each of three 4-day treatments of indomethacin (25 mg q 6hr), misoprostol (200 mcg q 6hr), or the combination of drugs with a 4-day washout between each treatment period. Measurements of GFR (urine accumulation of 99mTc-DTPA) and RPF (serum disappearance 131I-Hippuran), and urine collections for electrolytes were obtained before the first treatment period and on the fourth day of each treatment period. Three of the six hypertensive patients and three of the six normotensive patients had a decrease (greater than 10%) in GFR associated with indomethacin therapy. When misoprostol was given with the indomethacin, four of these six patients did not experience a decline in GFR (baseline GFR for six patients: 75.4 +/- 6.6 mL/min/1.73m2, GFR after indomethacin: 57.8 +/- 9.5 mL/min/1.73m2, GFR with combination of indomethacin and misoprostol: 69.7 +/- 3.5 mL/min/1.73m2. RPF was not consistently altered by subacute/chronic dosing of indomethacin, misoprostol, or the combination of the drugs. The authors conclude that misoprostol ameliorates indomethacin-induced renal dysfunction in salt-restricted and diuretic-treated middle-aged women with normal serum creatinine.

Alprostadil↗
PubMed1991

A molecular genetic approach to the identification of isochromosomes of chromosome 21.

The largest class of de novo chromosomal rearrangements in Down syndrome are rea(21q21q). Classically, these rearrangements have been termed Robertsonian translocations, implying an attachment of two different chromosome 21 homologues. Additionally, a Robertsonian translocation between two chromosomes 21 cannot be distinguished from an isochromosome composed of genetically identical arms by cytogenetic analyses. Therefore, we have used molecular techniques to differentiate between true Robertsonian translocations and isochromosomes. Samples were obtained from 12 probands, ascertained for de novo rearrangements between homologous chromosomes 21 [11 rea(21q21q) and 1 rea (21;21)(q22;q22)], their parents (n = 24) and available siblings (n = 7). The parental origins of the de novo rearrangements were assigned using molecular and cytogenetic analyses. Although not statistically significant, there was a two-fold increase in the number of paternally derived de novo rearrangements (n = 8) as compared with maternally derived rearrangements (n = 4). To distinguish between rob(21q21q) and i(21q), we used restriction fragment length polymorphisms (RFLPs) spanning the length of chromosome 21. Using all informative and partially informative RFLPs, we used the method of maximum likelihood to assign the most likely rearrangement definition (i or rob) and parental origin in each family. The maximum likelihood estimates indicated that all rearrangements tested (n = 8) were isochromosomes. C-banding revealed two centromeres in three cases indicating that a U-type exchange occurred between sister chromatids in these rearrangements. Our results suggest that the majority of de novo rea(21q21q) are isochromosomes derived from a single parental chromosome 21.

Cells, Cultured↗
PubMed1991

Prostaglandins in the kidney, urinary bladder and gills of the rainbow trout and European eel adapted to fresh water and seawater.

Prostaglandins in kidney, gills, and urinary bladder of freshwater-adapted and seawater-adapted rainbow trout, Oncorhynchus mykiss (= Salmo gairdneri), and European eel, Anguilla anguilla, were determined by solid-phase extraction of tissue homogenates and high-pressure liquid chromatography. Prostaglandins E2, E1, F1 alpha, F2 alpha, and D2 and the more stable metabolite of prostacyclin, 6-keto F1 alpha, occurred in these osmoregulatory tissues. In gill filaments and kidneys of both eel and trout, prostaglandins D2 and 6-keto F1 alpha were major prostaglandins. Concentrations of these prostaglandins were significantly lower in the eel after seawater adaptation, but not in the trout. The urinary bladder of the trout contained the highest levels of prostaglandins; bladders of seawater-adapted trout contained prostaglandin D2 at 6.7 ng/mg wet tissue, the highest level of any prostaglandin determined in the present studies. Prostaglandin D2 was not detected in bladders of freshwater-adapted trout.

Adaptation, Physiological↗
PubMed1991

Intracranial infection after missile injuries to the brain: report of 30 cases from the Lebanese conflict.

This study reviews the features of 30 intracranial infections complicating 600 penetrating head injuries from missiles in patients treated at the American University of Beirut Medical Center between 1981 and 1988. The follow-up period ranged from 1 month to 7 years (mean, 2.5 years). Sixteen patients had a brain abscess, 9 had cerebritis, 2 had an infected intracerebral hematoma, and 5 had meningitis. Infection developed 4 days to 7 years after the initial debridement. The infecting organisms were Gram positive in 11 patients (36%), Gram negative in 12 (40%), and a combination of Gram positive and Gram negative in 2 (7%). Twenty-four patients (80%) had wound dehiscence or cerebrospinal fluid leakage at the time the infection appeared. There was a 76% correlation between the organisms cultured from the dehiscent scalp wound and the brain. Twenty-three patients had intracranial retention of bone. Infection developed in 16 of the 30 patients (70%) around bone fragments, in 4 around a metallic fragment, in 2 around absorbable gelatin sponge, and in 3 along the missile tract; 2 had an infected intracerebral hematoma, and 3 had meningitis. At least one of the following risk factors was present in each patient: extensive brain injury, coma, trajectory through an air sinus, cerebrospinal fluid fistula, inadequate initial debridement, or incomplete dural closure. The incidence of intracranial infection in patients with postoperative retention of bone was 4% in the absence of scalp wound dehiscence, compared with 84.6% when wound dehiscence was present. Ten patients (43%) still retained a bone fragment measuring less than 1 cm after excision of a brain abscess or treatment of cerebritis or meningitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone and Bones↗
PubMed1991

Protein and antigen profiles of prevalent serovars of Leptospira interrogans.

Whole-cell and detergent-soluble proteins, enriched for outer membrane antigens, of the Leptospira interrogans serovars present in commercially available pentavalent vaccines (hardjo, pomona, icterohaemorrhagiae, grippotyphosa, and canicola) were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting (immunoblotting). Protein and antigenic profiles of these serovars, representing several serogroups, were compared with similar profiles of the most common North American bovine pathogen, serovar hardjo type hardjo bovis. The reference strain of serovar balcanica and a hardjoprajitno bovine field isolate (serovar hardjo) were also assayed. Coomassie blue-stained gels revealed extensive protein similarities, and Western blots demonstrated antigenic relatedness throughout the low- and high-molecular-weight regions. Possible quantitative differences in protein expression among the strains were noted, as were similarities in the protein profiles of type hardjo bovis and the balcanica reference strain. A cocktail composed of these homologous antigens may serve as an efficacious subunit vaccine for leptospirosis.

Animals↗