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Biomedical subjects

S Haynes

Publications and source records attributed to S Haynes.

At least 19 recordsLinked to original sources
PubMed2003

Diversity of bacteria associated with natural aphid populations.

The bacterial communities of aphids were investigated by terminal restriction fragment length polymorphism and denaturing gradient gel electrophoresis analysis of 16S rRNA gene fragments generated by PCR with general eubacterial primers. By both methods, the gamma-proteobacterium Buchnera was detected in laboratory cultures of six parthenogenetic lines of the pea aphid Acyrthosiphon pisum and one line of the black bean aphid Aphis fabae, and one or more of four previously described bacterial taxa were also detected in all aphid lines except one of A. pisum. These latter bacteria, collectively known as secondary symbionts or accessory bacteria, comprised three taxa of gamma-proteobacteria (R-type [PASS], T-type [PABS], and U-type [PAUS]) and a rickettsia (S-type [PAR]). Complementary analysis of aphids from natural populations of four aphid species (A. pisum [n = 74], Amphorophora rubi [n = 109], Aphis sarothamni [n = 42], and Microlophium carnosum [n = 101]) from a single geographical location revealed Buchnera and up to three taxa of accessory bacteria, but no other bacterial taxa, in each aphid. The prevalence of accessory bacterial taxa varied significantly among aphid species but not with the sampling month (between June and August 2000). These results indicate that the accessory bacterial taxa are distributed across multiple aphid species, although with variable prevalence, and that laboratory culture does not generally result in a shift in the bacterial community in aphids. Both the transmission patterns of the accessory bacteria between individual aphids and their impact on aphid fitness are suggested to influence the prevalence of accessory bacterial taxa in natural aphid populations.

Animals↗
PubMed2001

Coagulation factor activity during neonatal extra-corporeal membrane oxygenation.

OBJECTIVE: To ascertain the activity of major coagulation factors during the first 24 h of extra-corporeal membrane oxygenation (ECMO) used to support hypoxaemic neonates. DESIGN AND SETTING: A prospective observational study in a regional centre for ECMO and paediatric cardiac surgery, placing 15-20 neonates on ECMO per year. PATIENTS: Ten neonates receiving ECMO for severe hypoxaemia. MEASUREMENT AND RESULTS: The activity of major clotting factors, of the inhibitor anti-thrombin III and of markers of blood activation were measured during the first 24 h of neonatal extra-corporeal membrane oxygenation (ECMO) and prior to initiation of ECMO. There was laboratory evidence of factor deficiency and of activation of coagulation at all stages. The initiation of ECMO leads to an initial worsening of coagulopathy, but factor deficiency and abnormal activation of coagulation is also seen prior to ECMO in these very sick neonates. CONCLUSION: If factor deficiency is to be avoided a pro-active approach is required to rapidly correct factor activity. This would include the use of fresh frozen plasma. The effect of such an approach on outcome is at yet uncertain.

Biomarkers↗
PubMed2001

'Real life' clinical learning on an interprofessional training ward.

This paper describes the multi-method evaluation of an interprofessional training ward placement for medical, nursing, occupational therapy and physiotherapy students. Unique in the UK, and an extension of pioneering work in Sweden (Wahlström et al. 1997, Wahlstroöm & Sandén 1998), this interprofessional clinical placement allowed senior pre-qualifying students, under the supervision of practitioners, to plan and deliver interprofessional care for a group of orthopaedic and rheumatology patients. This responsibility enabled students to develop both their profession-specific skills in a real-world setting and the quality of their interprofessional teamwork. Student teams were supported by facilitators who led reflective sessions and acted as a resource for the students' problem-based learning. The training ward was evaluated by a multi-method approach, incorporating interviews, observations and questionnaires with students, patients and clinical staff. The evaluation findings have been grouped into a number of themes which offer an insight into the varying perspectives of training ward students, patients and staff. This paper pays particular attention to the nursing perspective of the interprofessional training ward pilot.

Education, Nursing↗
PubMed1999

Telomere length shortening is associated with disease evolution in chronic myelogenous leukemia.

We studied telomere length in the peripheral blood leukocyte samples of a large group of patients with chronic myelogenous leukemia (CML) by Southern blot hybridization using the (TTAGGG)4 probe. The average telomere length expressed as the peak telomere repeat array (TRA) of the peripheral blood samples obtained from a group of 34 healthy age-matched controls ranged between 7.6 and 10.0 kb and the mean peak TRA was 8.7 kb. Forty-one patients in the chronic phase of CML were studied; 32/41 (78%) showed telomere reduction (<7.6 kb) relative to age-matched controls and the mean peak TRA was 6.4 kb (range 4.0-10.6 kb). Serial samples were analysed from 12 patients at both chronic phase and during disease progression. The leukocyte DNA of all 12 patients in accelerated phase and/or blast crisis showed telomere reduction relative to age-matched controls and the mean peak TRA was 4.1 kb (range 3.0-5.4 kb). The peak TRA in the accelerated or blast phase was reduced compared with the corresponding paired sample in the chronic phase in all cases studied. These data show that a marked reduction in telomere length is associated with disease progression in CML.

Adult↗
PubMed1999

Intrathoracic tracheal rupture.

This paper reports five new cases of intrathoracic tracheal rupture in cats, and summarizes these cases in conjunction with 11 cases from the literature. Most cats had no obvious respiratory signs at the time of injury, and in half of them the tracheal rupture was the only injury. The interval from trauma to onset of dyspnoea ranged from 1 to 28 days (median 12.5 days). Radiographic findings include loss of continuity of the trachea, often with a gas-filled diverticulum present between separated tracheal rings. With careful attention to surgical technique and anaesthetic management the prognosis for these cats is excellent. All eight of the cats reported in the last 14 years having surgical correction survived and returned to normal. The surgical anatomy, approach and tracheal anastomosis technique is described and recommendations for anaesthetic management are made.

Animals↗
PubMed1999

Vascular surgical society of great britain and ireland: autologous transfusion reduces blood transfusion requirements in aortic surgery

BACKGROUND: Elective aortic surgery is associated with a blood loss that warrants a routine blood crossmatch of 4-6 units. Autologous transfusion strategies to reduce blood requirements were evaluated in a pilot study involving six hospitals in the North West. METHODS: Eighty patients undergoing elective aortic surgery were randomized to either autologous (a combination of acute normovolaemic haemodilution and intraoperative cell salvage) or homologous transfusion. The transfusion trigger, in the absence of pressing clinical need, was 8 g dl-1 haemoglobin for both groups. RESULTS: Randomization achieved two groups well matched for age, aneurysm or occlusive surgery, aspirin intake, estimated blood volume, preoperative haemoglobin and aneurysm size. In the 'best' hospitals (n = 49) mean(s.d.) blood loss (630(49) ml) was significantly lower (P < 0.01) than that in the 'worst' hospitals (1077(110) ml, n = 31) and fewer patients required transfusion (nine of 42 versus 15 of 30; P < 0.05). No significant differences were found between homologous and autologous groups for all variables measured in the 'best' hospitals. In the 'worst' hospitals blood requirements were significantly higher (P < 0.05) for the homologous group (800(112) ml) compared with the autologous group (489(65) ml), although blood loss was similar (1239(195) versus 915(92) ml respectively). CONCLUSION: Autologous transfusion techniques significantly reduced homologous blood requirements in aortic surgery where blood loss exceeded 800 ml.

Journal Article↗
PubMed1999

Pharmacokinetics of calcium absorption from two commercial calcium supplements.

This study was conducted to compare pharmacokinetic indices of calcium absorption after a single oral (500 mg calcium) load of Citracal (calcium citrate) and Os-Cal (calcium carbonate). In 18 postmenopausal normal women, venous blood samples were obtained for the measurement of calcium before and hourly for 6 hours after an oral ingestion of Citracal, Os-Cal, or placebo with a breakfast meal. The change in area under the curve (delta AUC) in serum calcium from preload was 2.5-fold greater for Citracal than Os-Cal, and the peak-basal variation in serum calcium was 76% higher for Citracal than Os-Cal. The increment in serum calcium from preload after Citracal administration was significantly higher than that obtained after placebo load during most time periods and significantly higher than that of Os-Cal at 1, 4, and 5 hours after load. In contrast, delta AUC and peak basal variation of Os-Cal did not differ significantly from placebo and increment in serum calcium was significantly increased from placebo only at 6 hours. In conclusion, Citracal is much more bioavailable than Os-Cal.

Absorption↗
PubMed1998

Converting enzyme inhibition causes hypocitraturia independent of acidosis or hypokalemia.

BACKGROUND: Angiotensin II stimulates the proximal tubular Na/H antiporter and increases proximal tubular cell pH. Because intracellular pH may affect urinary citrate excretion and enzymes responsible for renal citrate metabolism, the present studies examined the effect of enalapril, an angiotensin converting enzyme inhibitor, on the activity of renal cortical ATP citrate lyase and urinary citrate excretion. METHODS: Enalapril was given to rats (15 mg/kg/day) for seven days and to humans (10 mg twice daily) for 10 days. Blood and 24-hour urine samples were obtained in both groups. Renal cortical tissue from rats was analyzed for enzyme activity. RESULTS: In rats, enalapril decreased urinary citrate excretion by 88%. The change in urinary citrate was not associated with a difference in plasma pH, bicarbonate nor potassium concentration. However, similar to metabolic acidosis and hypokalemia, enalapril caused a 42% increase in renal cortical ATP citrate lyase activity. When given to humans, enalapril significantly decreased urinary citrate excretion and urine citrate concentration by 12% and 16%, respectively, without affecting plasma pH or electrolytes. CONCLUSIONS: Enalapril decreases urinary citrate in rats and humans. This is due, at least in part, to increases in cytosolic citrate metabolism through ATP citrate lyase in rats similar to that seen with chronic metabolic acidosis and hypokalemia. The effects of enalapril on urinary citrate and renal cortical ATP citrate lyase occur independently of acidosis or hypokalemia but may be due to intracellular acidosis that is common to all three conditions.

Acidosis↗
PubMed1997

Isolation from phage display libraries of single chain variable fragment antibodies that recognize conformational epitopes in the malaria vaccine candidate, apical membrane antigen-1.

Phage display of single chain variable fragment (scFv) antibodies is a powerful tool for the selection of important and useful antibody specificities. We have constructed such a library from mice protected from malaria challenge by immunization with recombinant Plasmodium chabaudi DS apical membrane antigen (AMA-1). Panning on refolded AMA-1 enriched a population of scFvs which specifically bound the antigen. The single chain antibodies recognize conformational epitopes on AMA-1 from the P. chabaudi DS strain but not on AMA-1 of the 556KA strain of P. chabaudi. A subset of the antibody fragments recognized AMA-1 from the human malaria parasite Plasmodium falciparum. Nucleotide sequencing revealed that at least four unique scFv genes were selected by the panning procedure. These scFv antibodies are valuable reagents for probing the structure and function of AMA-1 and will be used to test the feasibility of using recombinant antibodies in a passive immunization therapy against malaria.

Animals↗
PubMed1996

Absence of the beta subunit (cchb1) of the skeletal muscle dihydropyridine receptor alters expression of the alpha 1 subunit and eliminates excitation-contraction coupling.

The multisubunit (alpha 1s, alpha 2/delta, beta 1, and gamma) skeletal muscle dihydropyridine receptor transduces transverse tubule membrane depolarization into release of Ca2+ from the sarcoplasmic reticulum, and also acts as an L-type Ca2+ channel. The alpha 1s subunit contains the voltage sensor and channel pore, the kinetics of which are modified by the other subunits. To determine the role of the beta 1 subunit in channel activity and excitation-contraction coupling we have used gene targeting to inactivate the beta 1 gene. beta 1-null mice die at birth from asphyxia. Electrical stimulation of beta 1-null muscle fails to induce twitches, however, contractures are induced by caffeine. In isolated beta 1-null myotubes, action potentials are normal, but fail to elicit a Ca2+ transient. L-type Ca2+ current is decreased 10- to 20-fold in the beta 1-null cells compared with littermate controls. Immunohistochemistry of cultured myotubes shows that not only is the beta 1 subunit absent, but the amount of alpha 1s in the membrane also is undetectable. In contrast, the beta 1 subunit is localized appropriately in dysgenic, mdg/mdg, (alpha 1s-null) cells. Therefore, the beta 1 subunit may not only play an important role in the transport/insertion of the alpha 1s subunit into the membrane, but may be vital for the targeting of the muscle dihydropyridine receptor complex to the transverse tubule/sarcoplasmic reticulum junction.

Action Potentials↗
PubMed1996

The lack of influence of long-term potassium citrate and calcium citrate treatment in total body aluminum burden in patients with functioning kidneys.

BACKGROUND: It has been suggested that citrate salts might enhance aluminum (Al) absorption from a normal diet, posing a threat of Al toxicity even in subjects with normal renal function. We have recently reported that in normal subjects and patients with moderate renal failure, short-term treatment with tricalcium dicitrate (Ca3Cit2) does not significantly change urinary and serum Al levels. However, we have not assessed total body Al stores in patients on long-term citrate treatment. OBJECTIVE: The objective of this study was to ascertain body content of Al non-invasively using the increment in serum and urinary Al following the intravenous administration of deferoxamine (DFO) in patients with kidney stones and osteoporotic women undergoing long-term treatment with potassium citrate (K3Cit) or Ca3Cit2, respectively. METHODS: Ten patients with calcium nephrolithiasis and five with osteoporosis who were maintained on potassium citrate (40 mEq/day or more) or calcium citrate 800 mg calcium/day (40 mEq citrate) for 2 to 8 years, respectively, and 16 normal volunteers without a history of regular aluminum-containing antacid use participated in the study. All participants completed the 8 days of study, during which they were maintained on their regular home diet. Urinary Al excretion was measured during a two-day baseline before (Days 5, 6) and for 1 day (Day 7) immediately following a single intravenous dose of DFO (40 mg/kg). Blood for Al was obtained before DFO administration, and at 2, 5 and 24 hours following the start of the infusion. RESULTS: The median 24-hour urinary Al excretion (microgram/day) at baseline versus post-DFO value was 15.9 vs. 44.4 in the normal subjects and 13.3 vs. 35.7 in the patients. These values were all within normal limits and did not change significantly following DFO infusion (p = 0.003 and p = 0.0001, respectively). The median change of 17.1 micrograms/day in urinary Al in the normal subjects was not significantly different from the 18.7 micrograms/day change measured in the patient group (p = 0.30). Similarly, no change in the mean serum Al was detected at any time following the DFO infusion, either in the patient or control group (patients 4.1 to 4.3 ng/ml, controls 7.4 to 4.6 ng/ml). CONCLUSION: The results suggest that abnormal total body retention of Al does not occur during long-term citrate treatment in patients with functioning kidneys.

Adult↗
PubMed1995

The reproducibility and repeatability of the Wits analysis.

Since the introduction of the Wits analysis, the validity of the method has been questioned, as the functional occlusal plane in particular has been cited as a major source of error. This may be either subjectively placed or defined by existing cephalometric methods. A study is therefore reported of the repeatability (intraobserver comparison) and reproducibility (interobserver comparison) of the Wits assessment on the basis of a double series of tracings by each of two observers. No statistically significant difference was found for the repeatability of distance AO-BO by either observer, but interobserver repeatability was less satisfactory, and the mean values varied by approximately 75%. It was also found that the highest single error between two series of tracings was 3.1 mm (observer A) and 5.8 mm (observer B).

Adolescent↗
PubMed1994

Slow-release sodium fluoride in the management of postmenopausal osteoporosis. A randomized controlled trial.

OBJECTIVE: To test whether intermittent treatment with slow-release sodium fluoride and continuous calcium citrate supplementation inhibits vertebral fractures without causing fluoride complications. DESIGN: A placebo-controlled, randomized trial. SETTING: Outpatient setting of specialty clinics in Dallas and Temple, Texas. INTERVENTIONS: Slow-release sodium fluoride (25 mg twice daily) in repeated 14-month cycles (12 months on treatment followed by 2 months off treatment) compared with placebo. Both groups took calcium citrate (400 mg calcium twice daily) continuously. PATIENTS: 110 patients with postmenopausal osteoporosis were randomly assigned to two groups. In the slow-release sodium fluoride group, 48 of 54 patients completed more than 1 cycle of treatment (mean, 2.44 cycles/patient), whereas 51 of 56 patients in the placebo group completed at least 1 cycle (mean, 2.14 cycles/patient) in this interim analysis. MEASUREMENTS: Vertebral fracture rate and lumbar bone mineral content. Vertebral fractures were quantified from yearly radiographs. Bone mass was determined annually by densitometry. RESULTS: In the sodium fluoride group, the mean L2 to L4 bone mineral content increased by 4% to 6% in each cycle and the mean femoral neck bone density increased by 4.1% and 2.1% during the first two cycles, but the radial bone density did not change. The placebo group showed no statistical change in bone mass at any site. Compared with the placebo group, the sodium fluoride group had a lower individual new vertebral fracture rate (0.057/patient cycle compared with 0.204/patient cycle, P = 0.017), a higher fracture-free rate (83.3% compared with 64.7%, P = 0.042), and a lower group fracture rate (0.085/patient cycle compared with 0.239/patient cycle, P = 0.006). The side-effect profile was similar for the two groups; no patient developed microfractures, hip fractures, or blood loss anemia. CONCLUSIONS: Intermittent slow-release sodium fluoride plus continuous calcium citrate, administered for about 2.5 years, inhibits new vertebral fractures, increases the mean spinal bone mass without decreasing the radial shaft bone density, and is safe to use.

Aged↗
PubMed1994

Intermittent self-catheterisation--the key facts.

1. There is a lack of knowledge among health professionals about intermittent self-catheterisation. 2. The technique has improved quality of life for many people suffering from continence problems. 3. Intermittent self-catheterisation has many advantages over the use of permanent indwelling catheters.

Humans↗
PubMed1993

Inter- and intra-observer identification of landmarks used in the Delaire analysis.

The investigation of intra- and inter-observer tracing error of points S, N, ANS, A, B, Me, Go, and Ba (conventional cephalometric points) and some of the landmarks used in the Delaire analysis (FM, M, CT, Clp, and Br) shows that a high level of intra-observer repeatability was achieved for each landmark, and that no statistically significant differences occurred. Also there were no statistically significant differences on inter-observer comparison of averaged values for the replicate tracings of each observer. However, the gross error which may occur in an individual case may be of considerable clinical significance.

Adolescent↗