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D J Morris

Publications and source records attributed to D J Morris.

At least 55 records · Page 3Linked to original sources
PubMed1996

Comparison of primer sets for detection of fecal and ocular adenovirus infection using the polymerase chain reaction.

Adenoviruses of subgenus F (types 40 and 41) cause infantile gastroenteritis and adenoviruses principally of types 1-7 are found in feces during respiratory or generalized infections. Adenoviruses (mostly types 3, 4, 8, 19, or 37) are also linked with follicular or epidemic conjunctivitis. The diagnostic efficiency of the polymerase chain reaction (PCR) for adenoviruses was assessed using genus-reactive primers H1 and H2 or JCH1 and JCH2 or subgenus F-specific primers F1a and F2a. With diarrheal stool specimens containing subgenus F adenoviruses, F1a/F2a PCR achieved at least as high a positivity rate (75/76 [99%]) as electron microscopy (72/76 [95%]) and was more sensitive than polyclonal antibody-based immune electron microscopy (IEM) for subgenus identification (75/76 [99%] vs. 66/76 [87%], P = 0.008). Twenty-three subgenus F strains untypeable by monoclonal antibody-based IEM were typed as 40 (n = 4) or 41 (n = 19) by Hha I digestion of the PCR product. The genus-reactive primer pairs provided DNA amplification assays of generally equal efficiency on conjunctival swab specimens though possible nucleic acid degradation in DNA extracts during storage could have meant that JCH1/JCH2 PCR was truly the more sensitive. The use of either genus-reactive primer set on fecal specimens cannot be recommended because, although the positivity rates with subgenus F PCR positive specimens were high (70/75 [93%] for H1 and H2, 14/15 [93%] for JCH1 and JCH2), the detection rates were disappointing with similar specimens yielding nonsubgenus F adenoviruses.

Adenoviridae Infections↗
PubMed1996

Role of telomeric sequences in murine radiation-induced myeloid leukaemia.

A previous study indicated that a highly inbred CBA/H mouse colony contained four genotypic variants for telomere-like repeat (TLR) sequence arrays and that one variant subpopulation that constituted 20% of the colony contributed the vast majority (> 90%) of radiation-induced acute myeloid leukaemias (AMLs). Through screening of a satellite CBA/H colony and rescreening of the original colony, we show that, whereas germline telomere sequence polymorphism is frequent in CBA/H mice, there is no genetic link between a specific TLR locus variant and susceptibility to AML. Studies on telomere-hybridising fragments between 200 bp and 150 kb revealed that the germline telomere mutation frequency was highest for restriction fragments > 50 kb. The hypervariability of these high-molecular-weight fragments resulted in each CBA/H mouse from the highly inbred colony having a different genotype. Although it was not possible to ascribe a specific somatic telomere mutation to AML development, telomere rearrangements were common in induced AMLs. Some terminal telomere-hybridising restriction fragments were shortened in AML samples in comparison with normal tissue, but, insofar as the reduction in size was relatively small, it seems unlikely that telomere erosion is a major contributor to the molecular pathology of murine radiation-induced AML.

Animals↗
PubMed1996

Multiplex polymerase chain reaction for adenovirus and herpes simplex virus in eye swabs.

Adenoviruses and herpes simplex virus (HSV) can cause clinically indistinguishable episodes of acute eye disease. Adenovirus infection is associated with nosocomial outbreaks and HSV may result in episodes of recurrent ocular inflammation. In a comparison of multiplex PCR for the two viral DNAs and virus isolation in cell culture, identical results were obtained for 18 of 20 specimens (positive for adenovirus in 5, HSV in 5, and negative in 8). One specimen was falsely negative for each viral DNA. Inclusion of human beta-globin primers in the adenovirus-HSV reaction was precluded by a consequential 10--100-fold reduction in sensitivity for the two viral targets and by the failure of beta-globin DNA amplification at the annealing temperature (45 degrees C) required to ensure detection of adenoviruses of serotypes 7 and 11 with the selected adenovirus primers. A single-target beta-globin PCR gave positive results with 19 of the 20 specimens prepared by treatment with proteinase K lysis buffer, indicating the effectiveness of this simple DNA extraction procedure. Nonetheless, the availability of effective antiviral therapy for HSV made monitoring for extraction failure using human primers crucial to avoid false-negative results for HSV DNA. Adenovirus-HSV PCR has considerable potential for the rapid diagnosis of viral eye disease particularly if beta-globin primers can be included in the reaction.

Adenovirus Infections, Human↗
PubMed1996

Polymerase chain reaction for rapid diagnosis of respiratory adenovirus infection.

Endemic (type 1, 2, 5 and 6) and epidemic (type 3, 4 and 7) respiratory adenovirus infections are associated with upper respiratory tract symptoms, pharyngoconjunctival fever, and pneumonia. Improved methods of diagnosis are needed, particularly in immunocompromized patients. We examined 93 throat swabs or nasopharyngeal aspirates from patients with acute respiratory disease using virus isolation and an adenovirus-specific polymerase chain reaction (PCR) based on consensus primers H1 and H2 derived from the hexon region DNA sequences of serotypes 2 and 5. Specimens which yielded viruses other than adenovirus in cell culture (n = 23) or which were negative for infectious viruses (n = 25) were negative in the PCR. The sensitivity of DNA amplification was 76% (34/45) in comparison with virus culture, being markedly lower with subgenus B (types 3 and 7) strains than with subgenus C (type 1, 2, 5 and 6) isolates (8/16 (50%)) vs. 26/28 (93%). P = 0.004) despite the use of a low annealing temperature to maximize detection of adenoviruses belonging to subgenera other than C. Of the 11 samples falsely negative in a single-round PCR but yielding adenovirus type 1 (n = 1), type 2 (n = 1). type 3 (n = 7), type 7 (n = 1), or untyped isolates (n = 1) in cell culture, nine (82%) gave positive results after nested DNA amplification. Possible approaches to further improving the performance of adenovirus PCR with respiratory specimens are discussed.

Adenoviridae Infections↗
PubMed1996

Endogenous 11 beta-hydroxysteroid dehydrogenase inhibitors and their role in glucocorticoid Na+ retention and hypertension.

11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) metabolizes active glucocorticoids to their inactive 11-dehydro products and protects renal mineralocorticoid receptors from the high circulating levels of endogenous glucocorticoids. 11 beta-HSD has been suggested to be important not only in the control of renal sodium retention but also blood pressure. We had previously shown that 11 alpha- and 11 beta-hydroxyprogesterone (11 alpha- and 11 beta-OHP) were (I) potent inhibitors of 11 beta-HSD (Isoforms 1 and 2) activity in vitro, (ii) able to confer mineralocorticoid (MC) activity upon corticosterone (B) in vivo and (iii) hypertensinogenic when chronically infused into Sprague-Dawley (SD) rats. In addition we also showed that 3 alpha,5B-tetrahydroprogesterone (3 alpha,5B-THP) and chenodeoxycholic acid (CDCA) were potent inhibitors of 11 beta-HSD1 activity but not 11 beta-HSD2 activity, however, these substances were still able to confer MC activity upon B in the adrenalectomized rat. To assess the possible blood pressure modulating effects of 3 alpha,5B-THP and CDCA we have now infused these substances into intact SD rats continuously for 14 days. Both 3 alpha,5B-THP and CDCA caused a significant elevation in blood pressure within seven days, an effect that persisted throughout the 14-day infusion. These results show that both 3 alpha,5B-THP and CDCA are hypertensinogenic in the rat and that the inhibition of either 11 beta-HSD2 or 11 beta-HSD1 activity by endogenous progesterone metabolites and CDCA may be involved in the pathology of hypertension.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1996

Detection of herpes simplex virus DNA in donor cornea culture medium by polymerase chain reaction.

AIMS/BACKGROUND: Herpes simplex virus (HSV) may establish latent infection in the cornea and therefore be transmissible by corneal transplantation. Monitoring of donor cornea culture medium was evaluated for HSV infection. METHODS: HSV was sought using virus isolation in cell culture, and its DNA was amplified to detectable levels using the polymerase chain reaction (PCR). RESULTS: Virus isolation in cell culture was negative on neat, cell pellet, and cell free supernatant prepared from the spent culture media of 80 corneas. Three cell pellets (3.8%) were positive for HSV DNA. The PCR positive culture negative results might have reflected latent rather than active HSV infection of the cornea. Post transplant follow up of the three recipients of corneas with HSV PCR positive organ culture media revealed no evidence of HSV induced eye disease or primary graft failure. CONCLUSION: Screening of corneal culture medium for HSV by virus culture or for HSV DNA by PCR could not be recommended.

Aged↗
PubMed1996

11 alpha- and 11 beta-hydroxyprogesterone, potent inhibitors of 11 beta-hydroxysteroid dehydrogenase, possess hypertensinogenic activity in the rat.

The progesterone derivatives 11 alpha- and 11 beta-hydroxyprogesterone are potent inhibitors of 11 beta-hydroxysteroid dehydrogenase (isoforms 1 and 2) in vitro and can confer mineralocorticoid activity on corticosterone in the rat in vivo. 11 beta-Hydroxysteroid dehydrogenase metabolizes active glucocorticoids to their inactive 11-dehydro products and protects renal mineralocorticoid receptors from the high circulating levels of endogenous glucocorticoids. 11 beta-Hydroxysteroid dehydrogenase has been suggested to be important not only in the control of renal sodium retention but also of blood pressure. To assess the possible blood pressure-modulating effects of 11 alpha- and 11 beta-hydroxyprogesterone, we infused these substances into both intact and adrenalectomized Sprague-Dawley rats continuously for 14 days. Both 11 alpha- and 11 beta-hydroxyprogesterone caused a significant elevation in blood pressure within 3 days, an effect that persisted throughout the 14-day infusion. The hypertensive effects of 11 alpha-hydroxyprogesterone were abolished by adrenalectomy and significantly attenuated when 11 alpha-hydroxyprogesterone was infused together with the specific mineralocorticoid receptor antagonist RU28318. In an additional series of experiments, 11 alpha-hydroxyprogesterone significantly amplified the hypertensive effects of corticosterone in adrenalectomized spontaneously hypertensive rats but had no effects by itself in this experimental animal. These results demonstrate that both 11 alpha- and 11 beta-hydroxyprogesterone are potently hypertensinogenic in the rat and that this activity depends on an intact adrenal and at least in part on the activation of mineralocorticoid receptors. 11 beta-Hydroxyprogesterone, and similar endogenous progesterone metabolites that inhibit 11 beta-hydroxysteroid dehydrogenase, may be involved in the pathology of certain hypertensive states.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1995

Polymerase chain reaction for rapid detection of ocular adenovirus infection.

Adenoviruses are associated with endemic and epidemic acute conjunctivitis, large nosocomial outbreaks reflecting virus transmission on unwashed hands or inadequately sterilised ophthalmic instruments. The polymerase chain reaction (PCR) proved more sensitive than antigen detection by immune dot-blot test for the rapid diagnosis of ocular adenovirus infection (sensitivities in a retrospective study 112/123 (91%) versus 72/123 (59%), P < 0.001). Indeed, in a prospective comparison, DNA amplification and virus isolation generated similar numbers of positive results (34 versus 32), though five PCR positive results were possibly false positives. The sensitivity of the PCR was largely independent of adenovirus subgenus or serotype, though reduced sensitivity with subgenus B strains could not be excluded. Specimen preparation for DNA amplification using a simple lysis buffer proved more effective than phenol-chloroform extraction. The immune dot-blot test gave unavoidable false positive results, but with the PCR this problem could be minimized by technical modifications. The PCR could replace antigen detection and virus isolation as the initial test for adenoviruses in conjunctival swabs, with cell culture only being retained for adenovirus serotyping in PCR positive specimens and for other viruses such as herpes simplex.

Adenoviridae↗
PubMed1995

Bidirectional activity of 11 beta-hydroxysteroid dehydrogenase in vascular smooth muscle cells.

Endogenous glucocorticoids (GC) can be metabolized through the enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD); in the rat, corticosterone (B) is converted to its inactive metabolite 11-dehydrocorticosterone (A). Since increased tissue concentrations of GCs may affect blood pressure by potentiating the vasoactive effects of alpha-adrenergic agonists and possibly other pressors, we studied the metabolism of corticosterone in freshly dissected aortae and cultured vascular smooth muscle cells (VSMC). Incubations were generally conducted for 60 min with 10(-8) M steroid; steroids were isolated and identified by HPLC. In aortic minces stripped of endothelium, the oxo-reductase reaction of A back to B was nearly 4 times greater than the dehydrogenase reaction of B to A (2.8 +/- 0.5 x 10(-11) versus 7.3 +/- 1.0 x 10(-12) mol/mg protein). This pattern was also seen in cultured VSMC during growth and quiescent states (growth A to B 3.2 +/- 0.4 x 10(-12) versus B to A 9.7 +/- 0.9 x 10(-13) mol/mg protein; quiescent A to B 8.8 +/- 0.1 x 10(-12) versus B to A 1.2 +/- 0.2 x 10(-12) mol/mg protein). Enzyme activity in either direction was less during growth, correlating with a decrease in mRNA for 11 beta-OHSD. In cell homogenates containing 200 microM NADP(H), the enzyme functioned equally in either direction at pH 7.4 with an apparent Km for corticosterone of approximately 2 x 10(-7) M. Carbenoxolone, an inhibitor of 11 beta-OHSD, suppressed the dehydrogenase reaction to a greater degree than the reverse oxo-reductase reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1995

Pathogenesis of calciphylaxis: study of three cases with literature review.

Calciphylaxis is characterized by ischemic necrosis, primarily of skin. The early phase of the ischemia has not been studied, and the pathogenesis is uncertain. In this study of early calciphylaxis, the vessels responsible for the ischemia seem to be within the material available for microscopic review, and the various stenosing vascular lesions are quantified. A distinctive and previously described small vessel calcification with superimposed endovascular fibrosis is most common, and is much more frequent than two other lesions proposed to cause the ischemia (thrombosis and global calcific obliteration). The calcified stenotic vessels average 100 microns in diameter. Calcification precedes the endovascular fibrosis. Vessels with early endovascular fibroblastic activation are found statistically to be strongly associated with the presence of a giant cell reaction. This endovascular giant cell reaction has not been previously described in calciphylaxis. Two additional cases show similar findings. The histology resembles the reaction to calcium in a variety of other extraosseous calcification syndromes, for example, pseudogout, as if calciphylaxis were an endovascular form of calcium crystal-induced inflammatory disease. The literature is reviewed, and the clinicopathologic, radiographic, and therapeutic implications are discussed.

Aged↗
PubMed1995

Multiplex polymerase chain reaction for human herpesvirus-6, human cytomegalovirus, and human beta-globin DNA.

Human cytomegalovirus and human herpesvirus-6 are closely related viruses which cause similar diseases, have similar cellular repositories of latent infection, and may be detected largely in the same types of clinical specimens. DNA amplification appears likely to play an increasing role in the diagnosis of recent and remote infection with these agents. A sensitive multiplex polymerase chain reaction was therefore developed for the two viruses and for human beta-globin DNA. Optimization of parameters such as the primers, primer concentrations, magnesium concentration, and buffer constituents was crucial in achieving a sensitive assay. Preliminary results indicated that the assay could simultaneously monitor DNA extraction from clinical specimens and allow detection of HCMV or HHV-6 in patients with diseases possibly caused by either pathogen.

Base Sequence↗
PubMed1995

Effects of electrode configuration on threshold functions for electrical stimulation of the cochlea.

Psychophysical detection threshold vs frequency functions for sinusoidal electrical stimulation of the deafened cochlea were measured in 18 nonhuman primate subjects. Functions for monopolar or widely-spaced ( > 2.5 mm) bipolar stimulation were lower and usually had steeper slopes than those for more narrowly-spaced ( < 2.0 mm) bipolar stimulation. In 56% of the cases the difference between thresholds for narrowly-spaced bipolar of monopolar stimulation was greater for low frequency stimuli (63 or 100 Hz) than for high frequency stimuli (800 or 1,000 Hz) by 5 dB or more. Two cases were compared in more detail using pulsatile stimuli. For sinusoidal stimuli, one of these cases showed a moderate frequency dependent effect of electrode configuration and the other did not. The case with the frequency dependent effect of electrode configuration for sinusoids also showed a phase-duration dependent effect of electrode configuration for detection of single biphasic pulses: strength-duration curves (detection threshold in decibels vs pulse duration in ms/phase) were steeper for monopolar stimulation than for narrowly-spaced (0.7 mm) bipolar stimulation. This effect was not seen in the case that showed little or no frequency dependence in the effect of electrode configuration for sinusoidal stimuli. Slopes of threshold vs pulse rate functions where pulse duration was held constant at 2 ms/phase were not affected by electrode configuration in either subject.

Animal Welfare↗
PubMed1995

Prospective study of adenovirus antigen detection in eye swabs by radioimmune dot-blot.

Rapid laboratory diagnosis of ocular adenovirus infection is crucial in the containment of nosocomial transmission of the virus. In a large prospective study of adenovirus assay in eye swabs, antigen detection by radioimmune dot-blot (turnaround time 72 hours) achieved a sensitivity of 67% (239/355) and a specificity of 93% (3065/3285) in comparison with virus culture (median turnaround time 14 days). When specimens weakly reactive for adenovirus antigen, or equally reactive for both adenovirus antigen and Chlamydia trachomatis antigen, were considered falsely reactive in the adenovirus test, the sensitivity of the latter was reduced and false positive reactions were only marginally less frequent. The radioimmune dot-blot provides a more rapid diagnosis of ocular adenovirus infection than virus culture, but the high risk of false negative and in particular false positive results limits its clinical utility.

Adenovirus Infections, Human↗
PubMed1995

11 alpha- and 11 beta-hydroxyprogesterone, potent inhibitors of 11 beta-hydroxysteroid dehydrogenase (isoforms 1 and 2), confer marked mineralocorticoid activity on corticosterone in the ADX rat.

The effects of 11 alpha- and 11 beta-hydroxyprogesterone (11 alpha-OHP, 11 beta-OHP), on the activity of the glucocorticoid inactivating enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) were studied. 11 alpha-OHP and 11 beta-OHP were potent inhibitors of both 11 beta-HSD1 in rat liver microsomes and 11 beta-HSD2 in lysates of JEG-3 cells, a human choriocarcinoma cell line. In addition, both progesterone metabolites were markedly potent in conferring mineralocorticoid activity upon B in the adrenalectomized rat. These results provide insight into the structural properties required of inhibitors of 11 beta-HSD activity and indicate a possible role for endogenous 11 beta-HSD inhibitors in the regulation of glucocorticoid-induced Na+ retention.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1995

Effects of electrical current configuration on stimulus detection.

Psychophysical detection of electrical stimulation of the cochlea was studied as a function of electrical-current configuration. Subjects were postlingually deaf humans with Nucleus 20 + 2, Nucleus 22, and Ineraid cochlear implants and nonhuman primates unilaterally deafened and implanted with a multielectrode array similar to the Nucleus implant. In nonhuman primate and human Ineraid subjects, which had percutaneous connectors, we compared threshold functions for sinusoids and pulse trains for quadrupolar, bipolar, monopolar, and parallel multipolar stimulation. Thresholds decreased across this set of configurations. In some cases, the effects of current configuration were dependent on sinusoidal frequency and pulse duration. Pulse duration-dependent effects were also seen when comparing bipolar, monopolar, and common-ground configurations. Bipolar and monopolar stimulation were compared in Nucleus subjects using pulse trains at 50 microseconds per phase. For bipolar stimulation, thresholds decreased as a function of electrode separation, reaching a level near that for monopolar stimulation at separations of 3.5 to 6.5 mm in most cases. These results may be interpreted in terms of effects of current configuration on the magnitude and shape of electrical-potential fields produced in the cochlea, although more central factors also play a role in determining psychophysical detection thresholds.

Animals↗