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Biomedical subjects

G Nicholson

Publications and source records attributed to G Nicholson.

At least 73 records · Page 4Linked to original sources
PubMed1993

Purification and chemical characterization of staphyloferrin B, a hydrophilic siderophore from staphylococci.

This paper describes the chemical characterization of staphyloferrin B, a new complexone type siderophore isolated from low iron cultures of Staphylococcus hyicus DSM 20459. Purification of the very hydrophilic metabolite was achieved by anion exchange high performance liquid chromatography HPLC. Mass spectrometry showed a molecular mass of 448 amu. Hydrolysis with 8 M HCl revealed the presence of L-2,3-diaminopropionic acid, citrate, ethylenediamine and succinic semialdehyde. The connections between the four building blocks were determined by two-dimensional nuclear magnetic resonance measurements. UV/Vis and circular dichroism spectra are consistent with the proposed structure, which could also be confirmed by precursor feeding. The siderophore activity of staphyloferrin B was demonstrated by iron transport measurements.

Citrates↗
PubMed1993

Pregnancy and delivery in Charcot-Marie-Tooth disease type 1.

We report the obstetric complications and the influence of pregnancy and delivery in 21 Charcot-Marie-Tooth disease type 1 (CMT 1) patients with 45 gestations. Sixteen patients had subjective disabilities from childhood or youth, and five with late onset had subclinical CMT when they became pregnant. The rate of obstetric complications in the study group was in accordance with that of the normal population, and there was no deleterious effect on fetal outcome. Of the 21 participants, 38% (8 of 21) reported an exacerbation of CMT in at least one pregnancy. These patients noted increasing weakness in 81% (17 of 21) of their gestations. A temporary worsening occurred in 35% (6 of 17) of these pregnancies, and neurologic disabilities persisted after 65% of the deliveries (11 of 17). Patients who had pregnancy-associated progression in the first gestation (7 of 21) experienced similar deterioration in subsequent pregnancies (10 of 11), ie, there is a high risk for recurrence of exacerbations. Four women (19%) stated that their last deliveries were responsible for either an exacerbation or the onset of the neuropathy. The remaining nine patients (43%) denied any effect of their gestations on the progression of the neuropathy. Among the patients who had subjective disabilities from childhood or youth, the risk of a noticeable exacerbation in at least one pregnancy was 50% (8 of 16) and affected 81% of their gestations (17 of 21), whereas there was no influence of pregnancy in the five patients with adult onset of CMT, although the first symptoms were noticed postpartum in two of them.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Intermediate nerve conduction velocities define X-linked Charcot-Marie-Tooth neuropathy families.

Three genetic loci for the Charcot-Marie-Tooth (CMT) syndromes with slow motor nerve conduction velocities (hereditary motor and sensory neuropathy: HMSN type I) have been mapped to chromosomes 1 (CMT1B), 17 (CMT1A), and the X chromosome (CMTX). The clinical features of these three CMT subgroups are similar. To determine whether any clinical features distinguish CMTX families, the range of clinical findings and motor nerve conduction velocities were examined in two large CMTX families, the range of clinical findings and motor nerve conduction velocities were examined in two large CMTX families with CMTX proven by linkage to X-chromosome markers. CMTX males had more wasting and weakness than CMTX females or individuals with CMT1A. Patellar reflexes were more often retained in CMTX. Motor nerve conduction velocities were faster than in CMT1A. Intermediate-range median nerve conduction velocities were present in CMTX females (45 +/- 9 m/sec; range, 26 to 61 m/sec). These velocities were significantly faster than those for CMT1A females (22 +/- 8 m/sec, p < 0.0001). Median nerve conduction velocities in CMTX males (31 +/- 6 m/sec) were significantly slower than in CMTX females and faster than in CMT1A males (20 +/- 6 m/sec, p < 0.0001). The combination of slow conduction velocities in affected males (< 40 m/sec) and intermediate-range median motor conduction velocity results (> 40 m/sec) in affected or obligate carrier females is a useful distinguishing feature to separate CMTX from CMT1A, as intermediate conduction velocities are not present in autosomal-dominant dominant CMT1A families. This feature defines possible CMTX families for linkage studies. Families with no male-to-male inheritance of the syndrome, slow motor nerve conductions in affected males, and normal or intermediate-range conduction velocities in carrier females should be considered to be X-linked CMT families.

Adolescent↗
PubMed1991

Duodenal ulcer relapse after eradication of Helicobacter pylori.

Thirty-six patients with healed duodenal ulcers, 27 infected with Helicobacter pylori and nine uninfected, were followed for up to 12 months to determine the rate of ulcer relapse. Eight patients withdrew over the follow up period. At one year, 15 of 20 (75%) infected patients and one of eight (13%) uninfected patients had relapsed, p less than 0.05. Eradication of H pylori favourably influences the natural history of duodenal ulcer recurrence. Significant patient morbidity may be prevented by using measures to eradicate H pylori during or after duodenal ulcer healing.

Amoxicillin↗
PubMed1991

Unlinked surveillance of the prevalence of HIV infection in antenatal patients in the West Midlands, England.

In the course of an unlinked, anonymous survey of anti-HIV seroprevalence among antenatal patients in the West Midlands, carried out between November 1986 and March 1990, seven out of 202,012 patient samples were anti-HIV seropositive. Although the numbers of women infected by heterosexual contact are still low in this region, it is likely that HIV infection is no longer limited to well-defined, male risk groups. It is therefore increasingly important to monitor the course of the epidemic through large-scale unbiased surveys of the heterosexual population in order to plan future preventive and health-care strategies.

Adult↗
PubMed1991

Semi-quantitative assay of D antigen site density by flow cytometric analysis.

This study describes the comparative measurement of D antigen site density using a fluorescent indirect antiglobulin test (FIAT) read by flow cytometry. The test results confirmed the continuum of D antigen strength from weakest D through to R2R2 and also allowed the majority of weak D samples to be adequately distinguished from D-negative samples.

Erythrocytes↗
PubMed1989

Contamination of endoscopes used in AIDS patients.

Contamination of twenty endoscopes used in patients with AIDS was assessed. The suction-biopsy, air, and water channels and the insertion tube were sampled after use, after washing in detergent, and after disinfection for 2 min in 2% alkaline glutaraldehyde. The polymerase chain reaction with Southern blotting, cell cultures, and antigen immunoassay were used to detect human immunodeficiency virus (HIV). Samples were also examined for cytomegalovirus, adenoviruses, enteroviruses, herpes simplex virus, myxoviruses, hepatitis B surface antigen, fungi, and bacteria. Seven of twenty unwashed endoscopes were contaminated by HIV. Commensal bacteria were found in all endoscopes, Candida albicans in six, Staphylococcus aureus in five, and Pseudomonas aeruginosa in five. Washing alone removed all detectable organisms from 66 of 68 contaminated sites; Neisseria spp were recovered from two air channels after washing but not after disinfection. Washing achieved a mean reduction of 4.93 (95% confidence interval 3.69-6.17) colony forming units per ml.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Campylobacter pylori infection in Meckel's diverticula containing gastric mucosa.

A retrospective survey was undertaken of 228 resected Meckel's diverticula to determine if there was any evidence of Campylobacter pylori infection in diverticula containing gastric mucosa. Among the 65 diverticula with gastric mucosa one was heavily infected with organisms having the morphological appearances of C pylori. The specimen had been removed from a six year old Samoan boy who had been admitted with small bowel obstruction. Infection and associated mucosal inflammatory infiltrate were limited to areas of gastric mucosa only. The detection of the organism at this site remote from the gastroduodenal environment suggests the organism may be transmitted by the orofaecal route.

Campylobacter↗
PubMed1988

Campylobacter pylori infection in patients undergoing endoscopy in Fiji.

Forty two patients (20 Fijian and 22 Indian) presenting for endoscopy at the Colonial War Memorial Hospital, Suva, Fiji, were biopsied to detect Campylobacter pylori infection. Detection of the organism's urease activity in biopsy material or seeing the organism in Warthin-Starry silver stained histology sections were used to diagnose infection. Thirty-nine patients (93%) were infected; 19 of 20 Fijians (95%) and 20 of 22 Indians (91%). Of the 39 infected patients, 37 (95%) had chronic active gastritis and 24 (62%) had active peptic ulcer disease. The implications of these findings in relation to the management of endoscopy patients in Fiji are discussed.

Adult↗
PubMed1988

Distribution of Campylobacter pylori in the human stomach obtained at postmortem.

The distribution of Campylobacter pylori, its prevalence, and its relationship to gastritis and urease activity have been studied in 54 postmortem stomachs. Infection was confirmed by finding C. pylori in a Gram-stained smear of gastric mucus harvested from the entire stomach. Eight tissue specimens were obtained from predetermined sites from each stomach and examined for histologic gastritis and urease activity. Thirty-seven per cent of stomachs were infected, and of these 80% had widespread histologic gastritis. The detection of urease activity provided information on the distribution of the organism and had a high correlation with histologic gastritis. The organism is capable of infecting any area of the stomach. Infection is common and is more prevalent in Polynesian subjects (60%) than in Caucasians (19%).

Adolescent↗
PubMed1987

Ingestion of Campylobacter pyloridis causes gastritis and raised fasting gastric pH.

Campylobacter pyloridis was ingested by a volunteer who had a histologically normal gastric mucosa and fasting gastric pH recordings of less than 2. Three days later he developed moderate to severe attacks of epigastric pain. On the 5th day after ingestion C. pyloridis was cultured from antral biopsies which showed histological acute gastritis. However, fundal histology and fasting gastric pH were normal. On the 8th day fasting gastric pH rose to 7.6. On day 11 C. pyloridis was cultured from both antral and fundal biopsies which showed histological gastritis. Doxycycline was taken for 28 days but infection and gastritis persisted. Bismuth subsalicylate was taken for 28 days and final biopsies, taken 1 wk after stopping therapy, were culture negative. Histology showed a minimal residual chronic gastritis. C. pyloridis can cause an acute upper gastrointestinal illness associated with histological gastritis and an increase in fasting gastric pH.

Acute Disease↗
PubMed1986

Seroepidemiology of Campylobacter pyloridis.

A total of 1158 sera were tested by an enzyme linked immunosorbent assay (ELISA) for IgG and IgA antibodies to Campylobacter pyloridis. When used to test sera from gastroendoscopy patients this method had a sensitivity of 91% and a specificity of 75%. Ninety-eight of 108 infected patients (91%) were seropositive whereas only 23 of 92 (25%) uninfected patients were seropositive (p less than 0.001). Positive serology was also associated with histological gastritis (p less than 0.001). When sera from occupational groups were compared to random blood donor sera, meat workers, freezing works veterinary surgeons and pest control officers had significantly higher seropositivity. Cook Island (33 of 85 (39%)), Samoan (57 of 129 (44%)) and Tongan (39 of 56 (70%)) blood donors also had greater seropositivity than random blood donors (15 of 102 (15%)), (p less than 0.001 for all three ethnic groups). Seropositivity increased with age. The results indicate that C pyloridis infection is common among certain groups within New Zealand. The implication of this finding with respect to the hypothesis that C pyloridis is aetiologically related to dyspepsia and peptic ulcer disease is discussed.

Adolescent↗