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Biomedical subjects

J Ferguson

Publications and source records attributed to J Ferguson.

At least 163 records · Page 9Linked to original sources
PubMed1995

Cloning and characterization of the Streptomyces peucetius dnrQS genes encoding a daunosamine biosynthesis enzyme and a glycosyl transferase involved in daunorubicin biosynthesis.

The dnrQS genes from the daunorubicin producer Streptomyces peucetius were characterized by DNA sequencing, complementation analysis, and gene disruption. The dnrQ gene is required for daunosamine biosynthesis, and dnrS appears to encode a glycosyltransferase for the addition of the 2,3,6-trideoxy-3-aminohexose, daunosamine, to epsilon-rhodomycinone.

Amino Acid Sequence↗
PubMed1995

Regulation of daunorubicin production in Streptomyces peucetius by the dnrR2 locus.

Sequence analysis of the dnrR2 locus from the cluster of daunorubicin biosynthesis genes in Streptomyces peucetius ATCC 29050 has revealed the presence of two divergently transcribed open reading frames, dnrN and dnrO. The dnrN gene appears to encode a response regulator protein on the basis of conservation of the deduced amino acid sequence relative to those of known response regulators and the properties of the dnrN::aphII mutant. Surprisingly, amino acid substitutions (glutamate and asparagine) at the putative site of phosphorylation (aspartate 55) resulted in a reduction rather than a complete loss of DnrN activity. The deduced DnrO protein was found to be similar to the Streptomyces glaucescens tetracenomycin C resistance gene repressor (TcmR) and to two Escherichia coli repressors, the biotin operon repressor (BirA) and the tetracycline resistance gene repressor (TetR). The dnrN::aphII mutation was suppressed by introduction of the dnrI gene on a plasmid. Since the introduction of dnrN failed to restore antibiotic production to a dnrI::aphII mutant, these data suggest the presence of a regulatory cascade in which dnrN activates the transcription of dnrI, which in turn activates transcription of the daunorubicin biosynthesis genes.

Amino Acid Sequence↗
PubMed1995

Evaluation of a new, semiquantitative screening culture device for urine specimens.

The EZ Streak urine culture device (Difco Laboratories, Detroit, Mich.) combines the advantages of both the dip-slide and the classic urine culture technique, enabling bacterial enumeration and isolation following a simple inoculation step. Five hundred clean-catch urine specimens submitted by outpatients attending a health maintenance organization were used to compare the EZ Streak with culture using a 0.001-ml loop. Complete agreement of colony counts determined by the two methods was obtained for 114 (91.2%) of 125 positive specimens, but 99.2% of the results agreed in clinical interpretation, indicating the presence or absence of bacteriuria. Overall agreement between the EZ Streak and culture was 95.7%. The sensitivity and specificity of the EZ Streak were determined to be 98.4 and 99.4%, respectively. For this patient population, the EZ Streak was determined to be a reliable replacement for routine urine culture.

Bacteriological Techniques↗
PubMed1995

Follow up of an immunocompromised contact group of a case of open pulmonary tuberculosis on a renal unit.

BACKGROUND: The organisation, management, outcome and cost of follow up of a large group of mainly immunocompromised patients and healthcare workers who were exposed to a staff member of a London renal unit with smear positive pulmonary tuberculosis are described. METHODS: Following British Thoracic Society (BTS) guidelines, 576 close contacts were identified and divided into three groups: (1) 303 renal patients including 61 with renal transplants; (2) 90 surgical patients; and (3) 183 staff members. Screened contacts were interviewed, completed a symptoms questionnaire, and were offered a chest radiograph and Heaf or Mantoux test if appropriate with referral to a chest physician if required. RESULTS: Overall, 524 (85%) living contacts have been screened: 243 (97%) renal (first screening), 63 (70%) surgical, and 135 (74%) staff contacts. Thirty one transplant patients were prescribed isoniazid chemoprophylaxis. Fifty two renal patients had died before screening and 11 deaths occurred after first interview. One case of tuberculosis epidemiologically related to the index case was diagnosed on clinical criteria. A review of the case records and/or death certificates and entries on to tuberculosis registers indicated no further cases. The cost of the investigation was estimated to be approximately franc25 000, or franc44 per contact screened, with staff costs comprising 79% of the total. CONCLUSIONS: Undiagnosed tuberculosis in healthcare workers working with immunosuppressed patients can lead to large and expensive follow up studies. The applicability of the 1990 and 1994 BTS guidelines to the investigation of tuberculosis in an immunocompromised nosocomial group, and the role of the infection control doctor and the consultant in Communicable Disease Control in overlapping nosocomial and community incidents, are discussed.

Adolescent↗
PubMed1995

In vivo models of thrombogenic potential: usefulness and limitations.

The thrombogenicity of prothrombin complex concentrates (PCCs) has been known as a risk factor since their first clinical use about 30 years ago. The development of in vivo models to define the thrombogenic components in PCCs was instrumental in providing a logical basis for selecting in vitro assays to screen for the distribution of such components during the manufacture of PCCs, and to minimize their appearance in the final product. Even so, these thrombogenic components are not completely removed, as shown in our canine nonstasis model of thrombogenicity: PCCs were still found to elicit a thrombogenic response, shown by increased fibrinopeptide A, fibrin(ogen) degradation products, activated partial thromboplastin time, and decreased fibrinogen and platelet counts when clinically relevant doses were used. The new generation of high-purity factor IX (HP-FIX) concentrates differs from PCCs because these products contain only negligible amounts of clotting factors other than factor IX, lower amounts of activated clotting factors, and, in products we have assayed, no coagulant-active phospholipids. When we infused a number of HP-FIX products in the canine nonstasis model, no thrombogenic response was observed at doses considerably greater than PCC doses that did elicit a response. Likewise, HP-FIX products were much less thrombogenic than PCCs when tested in small-animal stasis and nonstasis thrombogenicity models. Small-animal models are also useful for evaluating the role of factor IXa as a potential thrombogenic contaminant of concentrates and ensuring minimal amounts in the final product. The limitations associated with extrapolating in vivo model data will be shown to be minimal if ongoing clinical studies continue to demonstrate the low thrombogenic potential of HP-FIX concentrates in humans.

Animals↗
PubMed1995

The diagnostic implication of falcine calcification on plain skull radiographs of patients with basal cell naevus syndrome and the incidence of falcine calcification in their relatives and two control groups.

The purpose of our study was to identify the incidence of falcine calcification shown on plain skull radiographs in people with basal cell naevus syndrome (BCNS) and in their relatives compared with a normal population. A population of people with BCNS and their relatives was identified on non-radiological grounds and the incidence of falcine calcification on skull radiographs in each of these two groups was compared with the incidence of falcine calcification in a control group of people and of a larger group who attended casualty departments. Falcine calcification was graded into dense, fine but definite, and faint. 85 people with BCNS had nearly 100% incidence of falcine calcification in adults. 83 first degree unaffected relatives showed no excess over "normal" incidence of falcine calcification. In the 970 casualty patients some falcine calcification was common (> 20%) in males over 30 and in females over 50 years of age. It occurred earlier and was more common in males than in females. Dense calcification occurred in 5-7% of females and males over 60 years of age. Dense calcification was rare (< 2%) under the age of 40 years. In conclusion, falcine calcification should be regarded as the fourth major feature and a very important diagnostic feature of BCNS. An adult labelled as a BCNS sufferer without falcine calcification probably has not got the syndrome. The genetic defect responsible for the metabolic defect resulting in dural calcification is probably the same as, or in close linkage disequilibrium to, that responsible for the major clinical features of the syndrome. The age and sex distribution of falcine calcification in a general hospital casualty population is described.

Adolescent↗
PubMed1995

The development of a post-operative pain service (1): An overview.

Slapping the patient on the face and saying: "It's all over" is a complete inversion of the truth. As far as the patient is concerned, it is just the beginning. This patient's view is supported by the report of a Working Party on Pain after Surgery which concluded that "the treatment of pain after surgery in British hospitals is inadequate and has not advanced significantly for many years". Yet failure to relieve pain is unacceptable not only for humanitarian reasons but also because unrelieved pain may inhibit optimal recovery. In their recommendations the Working Party placed a high priority on the establishment of an acute pain team in all acute general hospitals. This team would be responsible for education, research, audit, promoting pain assessment and ensuring adequate resources and safe practice.

Clinical Protocols↗
PubMed1995

Venlafaxine in depressed geriatric outpatients: an open-label clinical study.

A 12-month open-label clinical trial was conducted to evaluate patient acceptance and safety of venlafaxine, a novel antidepressant, in ambulatory geriatric depressed patients. The sample consisted of 58 depressed patients aged 65 years and older who needed long-term antidepressant treatment. The setting was multiple study sites in California, Florida, New York, Utah, and Washington. All patients took venlafaxine; 52 qualified for the intent-to-treat analysis, and 24 completed 12 months of treatment. Repeated-measures analysis of variance within subjects showed significant improvements in Clinical Global Impressions severity and improvement, Modified Symptom Checklist, and Quality of Life Questionnaire scores. One patient developed a rash that was judged to be a serious drug-related side effect. The most common side effects were headache (n = 25), nausea (n = 21), insomnia (n = 18), dry mouth (n = 18), and sweating (n = 18). The results demonstrate the safety and patient acceptance of venlafaxine in depressed geriatric outpatients for acute and maintenance treatment.

Aged↗
PubMed1995

The acoustic reflex at a 1000 Hz probe frequency: phasor and vector analysis.

Phasor plots of reflex growth functions have been inconclusive concerning the effect of the reflex for mass dominated ears. The present study aimed to establish whether vector plots clarified the effects of the reflex for phasors not showing a clear circular shape. Measured admittance data (ipsilateral reflexes across a wide intensity range) was represented as both phasor diagrams and converted to impedance quantities, represented as vectors. The results analysed for 34 ears showed few unclassifiable phasor diagrams. In addition, all growth functions showed increased stiffness on vector analysis. Resistance changes appeared to be variable. The results suggest that vector diagrams may be a useful way of representing data that is not clearly represented via phasor diagrams. The current study, however, does not clarify the pattern for mass dominated ears.

Adolescent↗
PubMed1995

Phase I evaluation of therapy with four schedules of 5-fluorouracil by continuous infusion combined with recombinant interferon alpha.

The purpose of this study was to determine the maximum tolerated dose and dose-limiting toxicities of 5-fluorouracil (5-FU) when administered concurrently with recombinant IFN-alpha using four continuous infusion (CI) dosing schedules of 5-FU. Forty-five patients with advanced or refractory cancers were treated with 5-FU by CI, plus IFN during the infusion only, by one of four schedules: schedule A: 24-h 5-FU infusion repeated weekly, 9 x 10(6) units IFN x 2 doses weekly; schedule B: 48-h 5-FU infusion repeated weekly, 9 x 10(6) units IFN x 4 doses weekly; schedule C: 5-day 5-FU infusion repeated every 3 weeks, 9 x 10(6) units IFN three times weekly; and schedule D: 21-day 5-FU infusion, repeated after 7 days off therapy, 9 x 10(6) units IFN three times weekly. At least three patients were treated at all dose levels. Doses of 5-FU were escalated to the next level if less than one half of the patients at a given level developed grades 2-4 toxicity. The maximum tolerated dose for 5-FU was 2150 mg/m2/week for schedule A (24-h CI), 2350 mg/m2/week for schedule B (48-h CI), 750 mg/m2/day for schedule C (5-day CI), and 175 mg/m2/day for schedule D (21-day CI). Median delivered dose intensities at these levels were 1788 mg/m2/week for schedule A, 2192 mg/m2/week for schedule B, 1250 mg/m2/week for schedule C, and 593 mg/m2/week for schedule D. The dose-limiting toxicities were hematological and gastrointestinal (stomatitis, diarrhea, nausea, anorexia) for schedules A and B and gastrointestinal (mostly stomatitis) for schedules C and D. Severe fatigue due to IFN was rare. Responses correlated with toxicity >/= grade 2, but not with increased dose intensity. Responses were noted in several tumor types on schedules A, B, and D. 5-FU can be combined with IFN using 24- and 48-h high-dose and long-term low-dose CI schedules, with large differences in dose intensity at maximum tolerated dose. Shorter infusions produce less mucosal and more hematological toxicity. Tumor responses were seen on both short- and long-term CI schedules. Future studies can establish the efficacies of these new schedules of 5-FU/IFN administration in specific tumor types.

Adult↗
PubMed1994

Morphology and birth dates of horizontal cells in the retina of a marsupial.

Most eutherian (placental) mammals have two horizontal cell types; however, one type only has been seen in rodents. In order to assess whether one type of horizontal cell or two is a basic mammalian feature, we have examined the morphology of horizontal cells in a marsupial, the quokka wallaby, by Golgi staining or horseradish peroxidase labelling. The birth dates of horizontal cells have also been determined by 3H-thymidine/autoradiography. There are two types of horizontal cell in the wallaby retina. One type has no axon and corresponds to the axonless cell in eutherian species; the other has shorter dendrites, an axon, and an axonal arbor, corresponding to the eutherian short-axon cell. As in eutherian mammals, the dendrites of each horizontal cell type lie in the outer plexiform layer (OPL) and contact cones and the axonal arbor of the short-axon cell contacts rods. The dendrites of the axonless cells are long, with an average length of 250 microns, and each cell has one, sometimes two, short, stubby processes, which branch off a dendrite, traverse the inner nuclear layer, and reach the inner plexiform layer. The dendritic field of these cells is elongated, and dendrites show a preferential orientation at right angles to the trajectory of overlying ganglion cell axons. Short-axon cells have a morphology similar to that seen in other species, although the axonal arbor is relatively small. Both types of horizontal cell are generated in the first phase of retinal cell generation.

Animals↗
PubMed1994

Lipohaemarthrosis in knee trauma: an experience of 907 cases.

The role of the horizontal beam lateral radiograph in the investigation of knee trauma was assessed by retrospective analysis of 907 cases presenting to a tertiary trauma unit. For each case the presence of a visible lipohaemarthrosis on the horizontal beam radiograph was correlated with the presence of an intra-articular fracture. Visible lipohaemarthrosis is a very specific sign of an intra-articular fracture (88.6 per cent), occurring in 27.1 per cent of cases. The authors propose that the horizontal beam lateral radiograph should be the standard lateral view in the investigation of knee trauma. The presence of a visible lipohaemarthrosis in the absence of a visible fracture, or isolated fracture of patella or fibula on the plain radiographs, are indications for further investigation.

Hemorrhage↗
PubMed1994

Induction of type I hypersensitivity in guinea pigs after inhalation of phthalic anhydride.

Guinea pigs were exposed through inhalation to phthalic anhydride (PA) dust at 0.5, 1.0, and 5.0 mg/m3, 3 hours/day for 5 consecutive days. Inhalation challenge with aerosolized phthalic anhydride-guinea pig serum albumin (PA-GPSA) conjugate elicited immediate-onset respiratory reactions in animals exposed to all three levels of dust. Inhalation challenge of a subgroup of animals with phthalic anhydride dust did not elicit an immediate response, as measured by changes in respiratory frequency and plethysmograph pressure. Serologic studies showed that these animals had allergic IgG1a antibody to PA-GPSA. There was a dose-dependent increase in specific IgG antibody activity, as measured by ELISA. Animals exposed to and challenged with 5.0 mg/m3 PA dust had significant numbers of hemorrhagic lung foci. Those animals with the greatest number of foci had high IgG antibody activity to PA, as measured by ELISA. This study showed that exposure to levels of PA dust as low as 0.5 mg/m3, below the current threshold limit value of 6.0 mg/m3, can sensitize animals to produce allergic antibody.

Administration, Inhalation↗
PubMed1994

Decrease of prostatic intraepithelial neoplasia following androgen deprivation therapy in patients with stage T3 carcinoma treated by radical prostatectomy.

OBJECTIVES: Prostatic intraepithelial neoplasia (PIN) is considered the most likely precursor of prostatic adenocarcinoma. The effect of androgen deprivation therapy on the prevalence of PIN is unknown. METHODS: We undertook a case-control study of radical retropubic prostatectomies from 24 treated patients and a control group of 24 untreated patients matched for age and clinical stage (all T3). Androgen deprivation therapy included LHRH agonist leuprolide and flutamide (18 patients), diethylstilbestrol (DES) (2 patients), DES with leuprolide and flutamide (1 patients), and orchiectomy (3 patients). Prostatectomy specimens were evaluated for the presence and extent of high-grade PIN according to the number of high-power microscopic fields, and nuclear tumor grade (1 to 4 scale) and Gleason score were also determined. RESULTS: The prevalence of high-grade PIN in pretreatment transrectal needle biopsies was similar in the treated and untreated groups. The prevalence and extent of high-grade PIN were lower in cases treated with androgen deprivation therapy than controls. Nuclear tumor grade was also lower in treated patients, but there was a paradoxical increase in the Gleason score. The prevalence of aneuploidy in the cancers was similar in both groups. CONCLUSIONS: These findings suggest that androgen deprivation therapy decreases the prevalence and extent of high-grade PIN.

Adenocarcinoma↗
PubMed1994

Effect of melatonin on human skin color.

Previous studies have shown the pineal hormone melatonin to influence mammalian coat color and amphibian skin color when administered exogenously. It has also been suggested that melatonin can be employed effectively to inhibit progress of neoplastic disease in both animals and humans. In the present study, we set out to investigate the effect of melatonin on human skin color in an effort to uncover its mechanism of action as an antimelanoma agent. We followed seven patients receiving orally administered melatonin over a mean duration of 19 months, and four controls who were not receiving melatonin, for an average of 12 months using monthly reflectometry measurements in three sites to determine skin color. There was no significant change in skin color among patients receiving melatonin, and no difference relative to controls. On the basis of these data, we conclude that melatonin has no effect on human skin pigmentation, and that the demonstrated effectiveness of melatonin in mediating malignant melanoma growth is not related to suppression of normal melanogenesis.

Administration, Oral↗
PubMed1994

Cellular sensitivity to oxidative stress in the photosensitivity dermatitis/actinic reticuloid syndrome.

Skin fibroblasts from certain patients with the photosensitivity dermatitis/actinic reticuloid syndrome show enhanced sensitivity to ultraviolet radiation compared to normal fibroblasts. To probe further the link between oxidative damage and this disease, we have obtained a more extensive set of cell lines from patients with a severe form of the disease and examined their sensitivity towards oxidative stress by measuring cell survival following UVA radiation (330-450 nm) or hydrogen peroxide treatment (0.1-2.4 mM). The activation of the stress gene, heme oxygenase, has also been assessed by measuring the accumulation of mRNA after hydrogen peroxide treatment. Our studies have confirmed that a slight ultraviolet sensitivity is a characteristic of photosensitivity dermatitis/actinic reticuloid syndrome cell strains and we further demonstrate that these cell lines are particularly sensitive to hydrogen peroxide with up to a three- to fourfold increased sensitivity as compared to normal controls. We also show that certain ataxia telangiectasia strains that are especially sensitive to hydrogen peroxide are also slightly sensitive to ultraviolet radiation. Hydrogen peroxide induces accumulation of mRNA for the oxidant-inducible stress protein, heme oxygenase, with similar kinetics (maximum mRNA accumulation 2-4 h following treatment) and with a similar range of magnitudes in both normal (6.6-20.6 times mRNA increase over basal levels) and photosensitivity dermatitis/actinic reticuloid (2.9-12.8 times) skin cells. Because cells from photosensitivity dermatitis/actinic reticuloid patients show increased sensitivity towards oxidative stress but show no significant change in oxidant activation of the heme oxygenase gene, we propose that the defect involves a late stage of processing of oxidative damage rather than a compromised free radical scavenging system.

Adolescent↗