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Biomedical subjects

R Wharton

Publications and source records attributed to R Wharton.

16 recordsLinked to original sources
PubMed1990

Acute deterioration of renal function associated with enteric hyperoxaluria.

Enteric hyperoxaluria due to malabsorption syndromes has been well documented to cause renal calculi and chronic tubulointerstitial renal damage. Rarely, in the setting of intestinal bypass operations for morbid obesity, enteric hyperoxaluria has produced acute renal failure. We report two patients who suffered acute deterioration of renal function associated with increased intestinal absorption and renal excretion of oxalate associated with steatorrhea. One patient had a large portion of his small bowel resected many years prior to the onset of the renal failure and the second patient had chronic pancreatitis causing steatorrhea. Both patients had renal biopsy documentation of the acute nature of the tubular damage produced by oxalate deposition. The mechanisms of their deterioration of renal function may relate to sudden increases in steatorrhea in association with episodes of volume depletion. Enteric hyperoxaluria may be an easily overlooked and potentially preventable etiology of acute renal dysfunction.

Acute Kidney Injury↗
PubMed1989

Restriction fragment length polymorphisms within proximal 15q and their use in molecular cytogenetics and the Prader-Willi syndrome.

Restriction fragment length polymorphisms (RFLPs) are described in detail for 6 DNA probes (D15S9-13, D15S18) that localize to the proximal long arm of human chromosome 15 (15q11-15q13: this report and Tantravahi et al., Am. J. Med. Genet. 33:78-87. Multiple RFLPs are detected by the probe that identifies locus D15S13, and these RFLPs are shown by genomic mapping to result from a nearby insertion or deletion of 1.8 kilobases (kb) of DNA. This set of RFLPs detected by proximal 15q probes can be used for studies on the Prader-Willi syndrome (PWS) and on mentally retarded individuals with a supernumerary inv dup(15) chromosome. Five of the polymorphic loci (D15S9-13) map to the region implicated in the cause of the PWS (15q11.2-15q12). Each of 4 families tested with these probes, as well as an additional "PWS-like" patient, was informative by RFLP analysis. The two PWS deletions studied, which occurred de novo, were inherited from the chromosome 15 provided by the father. By contrast, the 2 inv dup(15) chromosomes analyzed were of maternal origin. The use of RFLPs can also simplify the molecular determination of copy number in chromosomal aneuploidy, as exemplified by analysis of individuals with the PWS and a deletion, patients with an inv dup(15), and one patient with a more complex rearrangement involving chromosome 15. Our studies demonstrate the application of DNA probes for both molecular cytogenetic studies on this chromosome region and the development of diagnostic molecular markers to aid early clinical diagnosis of the PWS.

Chromosome Deletion↗
PubMed1989

Quantitative calibration and use of DNA probes for investigating chromosome abnormalities in the Prader-Willi syndrome.

Ten genomic DNA probes, subcloned from inserts derived from a phage library constructed from the DNA of flow-sorted chromosomes, have now been mapped to locations within 15q11-15q13. By dosage blotting and densitometry, 5 of these probes map to the 15q11.2-15q12 segment missing in one 15 chromosome of a Prader-Willi syndrome (PWS) patient with a prominent cytological deletion. A sixth probe most likely maps to the same region. The other 4 probes map outside of this segment but within 15q11-15q13. Several of the 15q11.2-15q12 probes, and a cDNA probe homologous to one, have been used to test the DNA from 8 patients exhibiting a wide range of the clinical manifestations expected for PWS patients. DNA deletion was observed in all 3 patients with cytological 15q1 deletions as well as in a patient with an unbalanced (Y;15) translocation. DNA from 1 PWS patient with an unbalanced (5;15) translocation and an inverted duplication of the short arm and proximal long arm of 15 showed at least 1 and possibly 2 extra copies of each genomic probe tested. In the other 3 patients with no cytological deletions, no DNA deletions were found. Thus, the molecular probes described can be used in most PWS patients to analyze the region of proximal 15q implicated in this syndrome.

Adolescent↗
PubMed1988

A repressor heterodimer binds to a chimeric operator.

Replacement of the solvent-exposed residues of the DNA recognition helix of the 434 repressor with the corresponding residues of the P22 repressor generates a hybrid protein, 434R[alpha 3(P22R)], which binds specifically to P22 operators. We show here that a new DNA-binding specificity is generated by combining 434 and 434R[alpha 3(P22R)] repressor monomers to form a heterodimer. The heterodimer specifically recognizes a chimeric P22/434 operator that lacks two-fold rotational symmetry.

Base Sequence↗
PubMed1988

Bacillus infections in patients with cancer.

Eighteen febrile patients experienced 24 episodes of Bacillus bacteremias from January 1978 to June 1986. Bacillus species isolated included Bacillus cereus (eight cases), Bacillus circulans (three), Bacillus subtilis (two), Bacillus pumilus (two), Bacillus licheniformis (one), Bacillus sphaericus (one), Bacillus coagulans (one), and six that could not be speciated. Fifteen patients had lymphoma or leukemia and three had breast cancer. Nine patients were neutropenic (polymorphonuclear neutrophil count, less than 1.0 x 10(9)/L), seven patients had a Hickman catheter in place, and 14 had recently received chemotherapy. Twelve of the bacteremic episodes were clinically significant, and four of these 12 involved Hickman catheters. Catheter removal was ultimately necessary in all four patients. Scanning and transmission electron microscopy was performed on one of the removed Hickman catheters and showed Bacillus organisms embedded in a biofilm composed of gram-positive cocci and glycocalyx. Bacillus species were uniformly susceptible to vancomycin, imipenem, and aminoglycosides, with penicillin susceptibilities being variable. Bacillus appears to be another gram-positive organism now being recognized as a bacterial pathogen for compromised hosts. When such infections involve long-term indwelling venous access devices, treatment should include immediate catheter removal as well as antibiotic therapy.

Adolescent↗
PubMed1987

Clinical heterogeneity associated with deletions in the long arm of chromosome 15: report of 3 new cases and their possible genetic significance.

Deletions, duplications, and rearrangements of the long arm of chromosome 15 are frequently associated with the clinical diagnosis of the Prader-Willi syndrome. However, a number of other clinical entities have also been associated with similar, if not identical, cytogenetic defects, arguing for clinical heterogeneity associated with abnormalities in this region of chromosome 15. We present 3 patients who all appear to have deletions in 15q11-15q12, such as described for many patients with Prader-Willi syndrome; however, none of these patients has classical clinical features of the Prader-Willi syndrome. The first patient is a child with Williams syndrome, the second, Angelman (Happy Puppet) syndrome, and the third is a child with hypotonia of infancy, obesity, and developmental delay, but who does not meet specific diagnostic criteria for the Prader-Willi syndrome. It is proposed that different molecular abnormalities involving specific points or segments along the long arm of chromosome 15 might account for the clinical diversity seen among these and other patients.

Abnormalities, Multiple↗
PubMed1986

Complementary medicine and the general practitioner.

The attitudes to complementary medicine of a random sample of general practitioners in Avon were assessed. A questionnaire was sent to 200 general practitioners, of whom 145 responded. The treatments studied were acupuncture, homoeopathy, herbal medicine, spinal manipulation, faith healing, and hypnosis. Of the 145 general practitioners, 55 (38%) had received some training in complementary medicine and 22 (15%) wished to arrange training. Overall, general practitioners knew little about the techniques of complementary medicine. Despite this 86 doctors (59%) thought that the complementary techniques being assessed were useful to their patients: 110 (76%) had referred patients for this type of treatment over the past year to medically qualified colleagues and 104 (72%) had referred patients to non-medically qualified practitioners. Most (93%) of those who responded believed that complementary practitioners needed statutory regulation; only 3% thought that they should be banned. The method of regulation most favoured was through a central and independent national body. General practitioners' views about complementary techniques were most influenced (in a positive manner) by observed benefits to their patients (41%) and personal or family experience of benefit (38%). The results of the study show a surprisingly high interest in complementary medicine among general practitioners in the Avon area.

Attitude of Health Personnel↗
PubMed1986

Antibiotic synergism and response in gram-negative bacteremia in granulocytopenic cancer patients.

To determine whether antimicrobial synergism affects the outcome of gram-negative bacteremia among profoundly (less than 100/microliter) neutropenic cancer patients, the clinical courses of 75 such patients who received empiric therapy with combination, broad-spectrum antibiotics were analyzed. Twenty-nine of 34 (85 percent) patients whose granulocyte count increased to more than 100/microliter during therapy improved, whereas only 12 of 41 (29 percent) patients with no increase in granulocyte count showed improvement (p = 0.0002). The critical group for further analysis was, therefore, those patients with persistent, profound granulocytopenia. Among these 41 patients, synergism was associated with a substantially better response rate: eight of 18 (44 percent) improved compared with none of 13 in whom synergism was not detected (p = 0.005); presence or absence of synergism could not be assessed for the pathogens isolated from the remaining 10 patients because the organisms were exquisitely susceptible to one of the two antibiotics used. Further evaluation of these persistently neutropenic patients indicated that synergism appeared critical even when the pathogen was susceptible to both antibiotics. Thus, seven of 11 (64 percent) showed response when the two drugs were synergistic in activity, compared with none of six when synergism was not present (p = 0.01). These data again demonstrate the importance of granulocyte recovery to patient response and further indicate that synergistic combinations of antibiotics are indicated for cancer patients with gram-negative bacteremia and persistent, profound granulocytopenia.

Agranulocytosis↗
PubMed1985

Violence on television and imitative behavior: impact on parenting practices.

In the past 30 years, four federal government commissions have reported on the relationship between television violence and aggressive behavior. The latest report concluded categorically that there is a causal relationship between television violence and aggressive behavior. Two infants were seen at an emergency room as a direct consequence of their socially isolated single mothers seeing a particular made-for-television movie. In one case, the infant died as a possible result of a parent imitating an act of child abuse; in the other case, early medical intervention precluded possible tragedy. These cases illustrate another way in which children may be victimized by violence on television; namely, by parents imitating inappropriate parental behavior. The origins of imitative behavior are discussed with specific reference to the impact on vulnerable parents. The concept of media-influenced parenting behavior is presented and implications for physicians are discussed.

Child Abuse↗
PubMed1984

Persistent isolation of an unusual Pseudomonas species from a phenolic disinfectant system.

A well-characterized unusual Pseudomonas species contaminated the piped disinfectant system of a newly-opened laminar air flow intensive care facility. This organism was frequently isolated (10(4)-10(6) cfu/ml) from phenolic diluted 1:256 in the system, and could also be recovered (0.01-0.2 cfu/ml) from undiluted phenolic. During the 20-month period when this unusual Pseudomonas was present, none of the severely compromised, granulocytopenic oncology patients treated in the intensive care facility were either colonized or infected with this Pseudomonas sp. Eradication of the organism from the system proved difficult and was accomplished by removing a contaminated reservoir of diluted phenolic disinfectant followed by transient cleansing of the system with very high concentrations (84,000 ppm) of chlorine. This experience demonstrates that phenolics should be added to the list of disinfectants which can harbor Pseudomonas spp. in the clinical setting.

Air Microbiology↗
PubMedDate not supplied

Moxalactam and piperacillin: a study of in vitro characteristics and pharmacokinetics in cancer patients.

We evaluated the microbiologic characteristics including MIC determinations, synergy plate assays and serum bactericidal activity for two regimens being examined as empiric antibiotic therapy for febrile granulocytopenic cancer patients. The regimens consisted of moxalactam (4 g.i.v. q12h) plus piperacillin (75 mg/kg i.v. q6h) or moxalactam (as above) plus amikacin (levels adjusted to one hour post-infusion levels of 25 mg/l and troughs of 6-8 mg/l). Detailed pharmacokinetics were ascertained for the beta lactams. All drugs were active against a panel of 11 strains each of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. The pharmacokinetic profile showed serum levels sufficient to provide good antimicrobial activity throughout the dosing interval. Both regimens displayed synergistic or partially synergistic activity in the main for the test organisms; moxalactam plus piperacillin produced good results against S. aureus and P. aeruginosa. In the serum bactericidal assays, the moxalactam-piperacillin combination produced significantly higher mean titers at both peak and trough when compared to the moxalactam-amikacin regimen. This may be because moxalactam acts as a beta lactamase inhibitor for both staphylococcal beta lactamase, as well as the Sabath-Abraham Id type beta lactamase carried by P. aeruginosa (among others). Moxalactam-piperacillin deserves extensive evaluation as empiric therapy for the febrile neutropenic cancer patients.

Amikacin↗
PubMedDate not supplied

Adolescent obesity.

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Adolescent↗