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Biomedical subjects

J Ramsey

Publications and source records attributed to J Ramsey.

At least 19 recordsLinked to original sources
PubMed2006

Unreduced gametes and neopolyploids in natural populations of Achillea borealis (Asteraceae).

Polyploidy is a major mechanism of speciation and adaptation, yet little is known about the origins of polyploids in natural species. I investigated gametic nonreduction and neopolyploid formation in natural tetraploid populations of Achillea borealis (Asteraceae), an autopolyploid complex consisting of tetraploid and hexaploid cytotypes. Cytological analyses of tetraploid populations revealed the occurrence of reduced (n=2x) as well as unreduced 'big' (2n=4x) and 'jumbo' (4n=8x) pollen grains, which were clearly distinguished by size. Production of unreduced pollen was monitored in two tetraploid populations in 1997 and 1998. Mean population-level frequencies of unreduced pollen ranged from 0.030 to 0.538%, with as few as one-third and as many as one-half of sampled plants producing unreduced grains. Eight individuals were found to produce >1% unreduced pollen, with highest observed frequencies of 7.0, 13.2 and 15.8%. Experimental crosses using high unreduced pollen producers as male parents generated viable seeds. However, the frequency of neohexaploids in the progeny of experimental crosses (0.388%) was similar to that observed in progeny of randomly selected, open-pollinated control parents (0.465%). These results suggest that unreduced eggs are the most likely source of new polyploids. In spite of the inefficiency of unreduced pollen in unilateral sexual polyploidization, the overall rate of neohexaploid formation (one in 233) was several orders of magnitude greater than estimates of genic mutation rates.

Achillea↗
PubMed2006

Chromosomal variation and genome size support existence of cryptic species of Triatoma dimidiata with different epidemiological importance as Chagas disease vectors.

The wide geographical distribution of Triatoma dimidiata, one of the three major vectors of Chagas disease, ranges from Mexico to northern Peru. Since this species occupies a great diversity of artificial and natural ecotopes, its eradication is extremely difficult. In order to assist control efforts, we used chromosome analyses and DNA amount as taxonomic markers to study genetic variability in populations of T. dimidiata from Mexico, Guatemala, El Salvador and Colombia. We differentiated three groups or cytotypes defined by characteristic chromosome C-banding patterns and genome size measured by flow cytometry. The three cytotypes are restricted to different geographic locations. Cytotype 1 occurs in Mexico (excluding Yucatán), Guatemala (excluding Petén), El Salvador and Colombia. Cytotype 2 occurs in Yucatán and cytotype 3 occurs in Petén. Cytotype 1, commonly associated with domestic and peridomestic environments but also inhabiting sylvatic ecotopes, is the most widespread and with major epidemiological significance. In contrast, the Yucatán cytotype inhabits wild ecotopes but increasingly enters houses, while the Petén cytotype appears exclusively sylvatic. We suggest that these cytotypes represent cryptic species of T. dimidiata with different epidemiological relevance as Chagas disease vectors. Poor ability to colonize human dwellings, together with their restricted geographic distribution, indicate that the Yucatán and Petén putative species probably have much less epidemiological significance than cytotype 1. Thus, the genetic markers we describe are powerful tools to differentiate cryptic species in T. dimidiata with different epidemiological significance, contributing to planning the most effective control measures.

Animals↗
PubMed2005

Cuticular hydrocarbon variability among Triatoma dimidiata (Hemiptera: Reduviidae) populations from Mexico and Guatemala.

The geographic variation in the cuticular hydrocarbon pattern among 11 populations of Triatoma dimidiata Latreille (Hemiptera: Reduviidae: Triatominae) from different regions of Mexico and Guatemala, was studied using capillary gas chromatography. T. dimidiata populations were differentiated based on the relative amounts of 71 hydrocarbon components. Insect population classification was mostly in agreement with their geographical vicinity; Mexican populations from the Yucatan peninsula grouped together with those from northern Guatemala, insects from the Mexican Gulf coast states were closely related to those collected from northern Oaxaca, and to a lesser extent, to insects from Chiapas. Insects from southern Oaxaca were clustered together with those from southern Guatemala. All these populations were clearly separated from Guatemalan specimens collected in caves from Alta Verapaz.

Animals↗
PubMed2001

Isoenzyme variability of five principal triatomine vector species of Chagas disease in Mexico.

Triatoma barberi, T. dimidiata, T. longipennis, T. pallidipennis and T. picturata, all key Chagas disease vectors in Mexico, were analysed by multilocus enzyme electrophoresis (MLEE) at 17 putative loci. The majority of insect specimens studied were collected from domestic and peridomestic structures from multiple geographic locations while others were collected from sylvatic areas. T. barberi was the least polymorphic species (P(0.95)=0.18), with polymorphism rates of the other species ranging from 0.29 to 0.50. T. barberi, a member of the protracta complex, clustered apart from the other studied species by Nei's genetic distance with >1.36, and at least eight loci were found to be diagnostic for this species. T. dimidiata was more related to T. longipennis, T. pallidipennis and T. picturata (phyllosoma complex) than to T. barberi, with a genetic distance averaging 0.36 with the phyllosoma complex species. In contrast, the genetic distances between the three phyllosoma complex species were not significantly different from zero, and there were no species-specific loci differentiating among them. The results strongly support the grouping of these three species in one complex, separate from the two other species studied.

Animals↗
PubMed2001

Induction of therapeutic antitumor antiangiogenesis by intratumoral injection of genetically engineered endostatin-producing Semliki Forest virus.

Antiangiogenic therapy using Semliki Forest virus (SFV) carrying Endostatin gene for malignant brain tumor was investigated to improve the therapeutic efficacy. The efficiency of SFV-mediated gene delivery was first evaluated for B 16 cells and compared with the efficiency in cells of endothelial origin (HMVECs). HMVECs are more susceptible to SFV infection than B 16 cells. For the in vivo treatment model, phosphate-buffered saline, SFV-LacZ, retrovirus vector GCsap-Endostatin, and SFV-Endostatin were injected to mice bearing B 16 brain tumors. A very significant inhibition of tumor growth was observed in the group that had been treated with SFV-Endostatin. A marked reduction of intratumoral vascularization was seen in the tumor sections from the SFV-Endostatin group compared with tumor sections from the SFV-LacZ or GCsap-Endostatin groups. Moreover, at day 7 after intravenous administration of SFV-Endostatin, the serum level of endostatin was augmented more than 3-fold compared to that after intravenous administration of GCsap-Endostatin. The results indicated that treatment with SFV-Endostatin inhibited the angiogenesis with established tumors. Gene therapy with Endostatin delivered via SFV may be a candidate for the development of new therapy for brain tumors.

Animals↗
PubMed2001

Ecstasy pill testing: harm minimization gone too far?

Harm reduction has become the focus of public health initiatives and therapeutic intervention in the management of dependent drug use over the last 20 years. The last decade has seen such approaches being extended to recreational drug use. Most harm reduction initiatives have aimed to inform users about risks and ways of minimizing risk. The concept of providing illicit drug users with quality assessment of their chosen drug is one possible harm reduction intervention that until recently has received little attention. In response to well-publicized 'ecstasy'-related deaths organizations in some European countries and the United States have chosen to provide a 'pill testing service' for users. There are two broad categories of pill testing offered. Simple colour reagent test kits (Marquis Reagent and colour charts) form the most widely used on-site pill testing method. Less frequently, but more accurately, laboratory personnel with access to sophisticated chromatographic equipment (high performance liquid chromatography (HPLC) or gas chromatography-mass spectrometry (GC-MS)) may provide analysis of a pill. Pill testing kits have been advocated as a 'tool to protect yourself against the polluted XTC market'. We refute this line of reasoning. Of the different tests only techniques such as GC-MS can identify satisfactorily the psychoactive constituents present in ecstasy pills. Colour tests based on an interpretation of a colour response in the presence of a drug are, at best, subjective. Pill testing of any description does not guarantee safety, or protect the consumer against individual responses to pills. At best it gives an artificial 'shine of safety' to a group of diverse drugs that remain both illicit and potentially harmful. Other simpler harm reduction mechanisms are likely to be more effective.

Chromatography, Gas↗
PubMed2001

The cost-effectiveness of a patient-sitter program in an acute care hospital: a test of the impact of sitters on the incidence of falls and patient satisfaction.

This article analyzes the costs and benefits of a patient-sitter program in relation to patient falls and patient satisfaction. During these days of intense budgetary scrutiny, it is necessary to integrate methods of cost/benefit analysis into our loss prevention management programs, whether physical loss or loss patient base due to dissatisfied patients. This article presents the research we have conducted to analyze costs and benefits of our patient-sitter program in relation to patient falls and patient satisfaction.

Accident Prevention↗
PubMed2000

Induction of a therapeutic antitumor immunological response by intratumoral injection of genetically engineered Semliki Forest virus to produce interleukin-12.

OBJECT: The authors investigated immunogene therapy for malignant glioma to determine whether its therapeutic efficacy could be improved. METHODS: Four groups of 203-glioma-bearing mice were treated with injections of phosphate-buffered saline, Semliki Forest virus (SFV)-LacZ, retrovirus vector DFG-interleukin (IL)-12, and SFV-IL12, respectively. The results indicated that therapeutic immunization with SFV-IL12 prolonged the survival of mice with established tumors. Semliki Forest virus induces apoptotic death to glioma cells, which facilitates the uptake of apoptotic cells by dendritic cells, providing a potential mechanism for enhanced immunogenicity. CONCLUSIONS: Immunogene therapy with IL-12 via SFV may be an excellent candidate for the development of new cancer vaccines.

Animals↗
PubMed2000

Sloughing of corneal epithelium and wound healing complications associated with laser in situ keratomileusis in patients with epithelial basement membrane dystrophy.

PURPOSE: To report sloughing of corneal epithelium during laser in situ keratomileusis and subsequent wound healing complications in patients with epithelial basement membrane dystrophy. METHODS: In a retrospective study, the surgical procedures, postoperative course, and visual acuities of 16 eyes of nine patients with epithelial basement membrane dystrophy who underwent laser in situ keratomileusis complicated with epithelial sloughing at three centers were reviewed. The mean follow-up period was 23 weeks (range, 4 to 52 weeks). RESULTS: In 13 (81%) of 16 eyes with epithelial basement membrane dystrophy, epithelial sloughing occurred during laser in situ keratomileusis. In eight of the 13 eyes, epithelial growth beneath the flap was observed. The flap was lifted and the interface epithelium scraped in six eyes. Flap melt or keratolysis occurred in four eyes. At the last follow-up visit, 13 of 16 eyes had an uncorrected visual acuity of 20/30 or better, and all eyes had a best-corrected visual acuity of 20/30 or better. CONCLUSIONS: Patients with epithelial basement membrane dystrophy have poorly adherent corneal epithelium and are predisposed to epithelial sloughing during the microkeratome pass of laser in situ keratomileusis. This may lead to flap distortion, interface epithelial growth, flap keratolysis, and corneal scarring. It is not recommended that laser in situ keratomileusis be performed in patients with classic, symptomatic epithelial basement membrane dystrophy. In patients who present with mild and asymptomatic epithelial basement membrane dystrophy, laser in situ keratomileusis should be performed with caution, or photorefractive keratectomy may be the preferred refractive procedure.

Adult↗
PubMed2000

Regulating surrogacy--a contravention of human rights?

On the 2nd of October 2000, The Human Rights Act 1998 came into full force, signalling the incorporation of The European Convention on Human Rights into U.K. law. Areas of law believed to be inconsistent with the Convention may now be challenged in both The European Court of Human Rights and domestic courts. This article considers whether existing laws on the regulation of access to infertility services, in particular surrogacy, will be deemed incompatible with the ECHR. Human rights as enshrined within Articles 8 and 12 will be examined in light of recent suggestions that there may arise legal challenges by those who have had access to reproductive services restricted or denied. It will be shown that, although existing and potential future controls may arguably infringe these rights, it is nevertheless unlikely that they will be held to be in contravention of The Human Rights Act 1998.

Europe↗
PubMed1998

Clinical and endocrine effects of a microdose GnRH agonist flare regimen administered to poor responders who are undergoing in vitro fertilization.

OBJECTIVE: To assess the endocrine and clinical responses to microdose GnRH agonist (GnRH-a) that was administered in the early follicular phase before controlled ovarian hyperstimulation to poor responders who were candidates for IVF-ET. DESIGN: Prospective nonrandomized trial with historical controls. SETTING: Tertiary care university-affiliated infertility practice. PATIENT(S): Thirty-four IVF-ET candidates with a prior poor response to a standard long-protocol GnRH-a controlled ovarian hyperstimulation regimen (cycle A). Patients were divided into two groups based on their age at the initiation of cycle A (Group 1: < or = 39 years, n = 15; Group 2: > or = 40 years, n = 19). INTERVENTION(S): Low-dose oral contraceptive (x 21 d) followed by GnRH-a (leuprolide acetate; 40 micrograms s.c. b.i.d.) flare and urofollitropin initiated on day 3 of GnRH-a administration (cycle B). MAIN OUTCOME MEASURE(S): Comparative analysis of clinical responses (total urofollitropin dose used and number of oocytes retrieved as well as fertilization and clinical and ongoing pregnancy rates) and endocrine responses (serum E2, FSH, LH, T, and P levels) between cycles A and B in the two groups. Early follicular phase serum E2 and FSH changes in groups 1 and 2 were compared with changes in nine normal responder controls who were receiving a standard long-protocol GnRH-a/urofollitropin regimen (group 3). RESULT(S): Maximal E2 levels as well as clinical and ongoing pregnancy rates were higher in cycle B patients receiving microdose GnRH-a. Cancellation rates in cycle B were lower than in cycle A. Statistically significant increases in treatment day 6 serum FSH levels were noted during cycle B in both groups 1 and 2 but not in group 3 controls. No abnormal rises in LH, P, or T were noted in any of the groups. CONCLUSION(S): Microdose GnRH-a enhances urofollitropin response and clinical outcome in poor responders undergoing IVF-ET. This may be due to enhanced release of early follicular phase endogenous FSH without concomitant deleterious rises in androgen levels or corpus luteum rescue.

Adult↗
PubMed1998

Assessment of practice in pre-registration nurse education and the development of a skills acquisition manual.

It has been suggested that Project 2000 training has not taken account of the need to assess the development of specific nursing skills. This could result in nurses who may be in a vulnerable position upon qualification regarding the expectations of their skills performance. A new initiative has been developed at the University of Luton, which enables specific skills to be assessed for pre-registration students during the Common Foundation Programme. This document is discussed here and is the precursor to a wider research study proposed to be undertaken upon completion of the evaluation.

Clinical Competence↗
PubMed1998

Venipuncture in the medical physiology laboratory.

Medical physiology laboratories, traditionally devoted to animal experimentation, face unprecedented difficulties linked to cost, staffing, instrumentation, and the use of animals. At the same time, laboratory experiences with living creatures play a unique role in medical education. In this article we describe the use of venipuncture and subsequent blood analysis, with medical students serving as both subjects and experimenters, in a sequence of first-year physiology laboratories. These experiments are safe, robust, inexpensive, and time efficient, and they teach the principles of cardiovascular, respiratory, renal, nutritional, and gastrointestinal physiology. In addition, they enhance medical education in several other important dimensions. First, they teach safe venous blood collection and handling, a training appropriate for students at this level. Second, by serving each week as subjects as well as experimenters, students experience aspects of both sides of the doctor-patient relationship. Third, the laboratories can be used to teach fundamentals of research design and analysis. Finally, because blood analysis is central to medicine, and because the student's own blood data are discussed, students are enthusiastic and cooperative, and the clinical relevance of the data is clear.

Clinical Laboratory Techniques↗