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Biomedical subjects

B Baker

Publications and source records attributed to B Baker.

At least 19 recordsLinked to original sources
PubMed2006

Artificial perfusion of the fetal circulation of the in situ mouse placenta: methodology and validation.

Here we present methodology and validation (including measurement of unidirectional maternofetal clearance (Kmf) of (45)Ca and (14)C-mannitol) for in situ perfusion of the mouse placenta. On day 18 of gestation (term=19 days) mice were anaesthetised and the uterus delivered into a saline bath (40 degrees C). A fetus was selected, the umbilical artery and vein catheterised and perfused with Krebs Ringer (pH 7.4) at 60 microl/min. (45)Ca/(14)C-mannitol (2 microCi/5 microCi in 50 microl saline) was injected via maternal tail vein. Perfusate samples were collected every 5 min for 45 min. Maternal carotid artery pressure was monitored throughout perfusion. A terminal maternal cardiac blood sample was taken and analysed. Placentas were immersion fixed and processed for electron microscopy. Kmf for (45)Ca and (14)C-mannitol was calculated as perfusate [(45)Ca or (14)C-mannitol] x perfusion rate/maternal plasma [(45)Ca or (14)C-mannitol]xplacental weight. Maternal cardiac blood chemistry at termination (n=8-15, mean+/-SEM) was as follows: pH 7.153+/-0.016, PCO(2) 45.48+/-2.06 mmHg, PO(2) 66.47+/-7.10 mmHg, Na(+) 151.4+/-1.2 mmol/l, K(+) 5.54+/-0.17 mmol/l, Ca(2+) 1.15+/-0.03 mmol/l, glucose 7.2+/-0.5 mmol/l, and lactate 1.76+/-0.77 mmol/l. A successful 45 min perfusion in which perfusate recovery was >95% occurred in >50% of animals. Perfusion did not alter placental morphology or carotid pressure. Kmf (microl/min/g placenta) for (45)Ca (66.0+/-8.4 (n=7)) was significantly higher than Kmf for (14)C-mannitol (20.0+/-2.4 (n=5)) (p<0.01). These data demonstrate physiological perfusion of the mouse placenta in situ and its usefulness for measurement of solute transfer.

Animals↗
PubMed2006

Cardiopulmonary bypass surgery in a patient with paroxysmal nocturnal haemoglobinuria.

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare acquired haemolytic anaemia. Cardiac bypass surgery in patients with PNH may be complicated by aggravation of haemolysis in addition to increased risk of infection, renal failure, bleeding and thrombosis. We describe a case of uncomplicated cardiopulmonary bypass surgery for aortic valve replacement and aortoplasty in a patient with PNH and discuss some recommendations to reduce the risk of peri-operative complications.

Aged↗
PubMed2005

Warfarin induction at 5 mg daily is safe with a low risk of anticoagulant overdose: results of an audit of patients with deep vein thrombosis commencing warfarin.

BACKGROUND: Conventionally warfarin therapy is initiated using a loading dose given over several days. Daily international normalised ratio (INR) monitoring is recommended to prevent overdose; however, with a large proportion of patients with deep vein thrombosis now receiving treatment out of hospital daily blood tests are inconvenient. We introduced a low-dose protocol for starting anticoagulant therapy that only required INR testing on days 4 and 6 and audited the results to assess safety and efficacy. METHODS: Two-hundred and forty-eight patients with confirmed deep vein thrombosis were started on warfarin therapy at 5 mg daily for 3 days. INR measurements were taken at day 4 and day 6. RESULTS: Of these patients, 21% had an INR within the therapeutic range on day 4 and 52% had a therapeutic INR on day 6. The risk of overdose was small with only one case with an INR above 4.0 on day 4 and nine cases on day 6. There were no reported cases of bleeding. CONCLUSION: The low-dose protocol with infrequent testing is safe and convenient for outpatient management. However, our results suggest that patients on this protocol take between 6-10 days to achieve a stable INR.

Adolescent↗
PubMed2003

Intra-alveolar distraction osteogenesis in preparation for dental implant placement combined with orthodontic/orthognathic surgical treatment: a case report.

The use of implants has become a routine part of restorative dental treatment. The placement of implants requires a sufficient quantity of bone in which to place implant fixtures. Where such bone does not exist, a number of methods have been used to augment the affected area of the alveolar ridge. This case report describes the use of the relatively new distraction osteogenesis procedure to increase bone volume in a patient who required post-traumatic restoration of several missing teeth, as well as comprehensive orthodontic and orthognathic surgical treatment.

Adolescent↗
PubMed2003

High prevalence of MMTV-like env gene sequences in gestational breast cancer.

Gestational breast cancer (BC) is generally associated with rapid growth and increased mortality. Because the presence of MMTV-like sequences in BC has been associated with laminin receptor expression, a marker of poor prognosis, gestational BCs were analyzed for MMTV env gene-like sequences to explore whether MMTV-like sequences were also associated with its adverse outcome. Whereas 30-38% of sporadic BC have the sequences, in gestational BC the prevalence is 62%. We suggest that hormonal response elements present in the MMTV-like LTR may play a role in promoting cell growth, as they do in the mouse system.

Animals↗
PubMed2002

Rocuronium plasma concentrations during three phases of liver transplantation: relationship with early postoperative graft liver function.

BACKGROUND: Previous studies have suggested that neuromuscular blocking agents might be used to assess liver function during liver transplantation. This study examines changes in rocuronium plasma concentration during liver transplantation, to assess graft function. METHODS: A constant-rate infusion of rocuronium was administered to 17 adult patients undergoing liver transplantation. Blood samples were taken at 30-min intervals throughout the procedure, which was divided into three phases: paleo-, an-, and neohepatic. Assay of plasma concentrations of rocuronium was by a gas chromatographic-mass spectrometry technique. Postoperative liver function was followed for up to five days by measuring plasma aminotransferases. RESULTS: In 14 of the 15 patients who survived the transplantation procedure, there was a 7-50% decrease in rocuronium concentration during the neohepatic phase compared with the anhepatic phase. In contrast, rocuronium concentrations increased in the two patients who died after surgery, one as a result of primary non-function and one from massive bleeding. In one patient who survived there was no change in rocuronium concentration. The increase in plasma rocuronium concentration during the neohepatic phase in the two patients who died was consistent with high levels of plasma aminotransferases. CONCLUSIONS: Comparison of changes in plasma rocuronium concentration during the neohepatic phase with early postoperative liver function tests suggests the potential use of rocuronium as a pharmacokinetic probe for predicting liver function during liver transplantation. Further study of rocuronium's potential as an intraoperative pharmacodynamic probe of liver function by measuring neuromuscular paralysis is suggested.

Adult↗
PubMed2001

Gas chromatographic-mass spectrometric assay for rocuronium with potential for quantifying its metabolite, 17-desacetylrocuronium, in human plasma.

A rapid, sensitive and selective method has been developed for the quantification of plasma concentrations of neuromuscular blocking drug, rocuronium, using gas chromatography with mass spectrometric detection. 3-Desacetylvecuronium served as the internal standard. The method involved iodide ion pair formation and a single-step liquid-liquid extraction with dicholoromethane. This method also permits simultaneous determination of its putative metabolite, 17-desacetylrocuronium, although the high detection limit for the metabolite limits the practical application of this method in pharmacokinetic study of the metabolite. The extraction efficiency was approximately 75% for rocuronium and approximately 50% for 17-desacetylrocuronium. The limit of quantification was 26 ng/ml for rocuronium and 870 ng/ml for its metabolite. The assay was used successfully in a patient undergoing liver transplantation and receiving rocuronium as a constant rate infusion and in a patient undergoing general elective surgery receiving the drug as an intravenous bolus. This assay is a time-saving alternative to published gas or liquid chromatographic methods for assaying rocuronium.

Androstanols↗
PubMed2001

Canopy level fluxes of 2-methyl-3-buten-2-ol, acetone, and methanol by a portable relaxed eddy accumulation system.

Canopy level flux measurements of 2-methyl-3-buten-2-ol (MBO), acetone, and methanol were made over a subalpine forest in the Rocky Mountains in Colorado in the summer of 1999. The measurements were carried out using a portable relaxed eddy accumulation system that collected samples on adsorbent cartridges. Midday fluxes of acetone were highest at approximately 2.5 mg of C m-2 h-1. Methanol and MBO fluxes were approximately 1.0 mg of C m-2 h-1 each. These fluxes occurred with average daytime high temperatures of only 18 degrees C. Diurnal fluxes of MBO were strongly correlated with light and temperature. Acetone and methanol did not have simple diurnal patterns. These results indicate that oxygenated volatile organic compounds may make a significant contribution to the flux of reactive carbon to the atmosphere in western U.S. pine forests.

Acetone↗
PubMed2001

The rapid whole blood agglutination d-dimer assay has poor sensitivity for use as an exclusion test in suspected deep vein thrombosis.

AIMS: Several clinical studies have proposed using d-dimer as an initial screening test to exclude thrombosis in cases of suspected (DVT). In published series, these assays have variable sensitivity, raising concerns that they may not be sufficiently robust for clinical practice. The aim of the study was to examine the sensitivity of two commercially available d-dimer assays and to assess their value and safety as initial screening tests in suspected DVT. METHODS: In this prospective study, blood samples were collected for d-dimer measurement (SimpliRED assay and IL test d-dimer) in all patients presenting to the emergency department over a twelve month period. All patients underwent compression ultrasound scanning as the primary diagnostic procedure. RESULTS: 235 patients were included in the study. 51(22.8%) had a DVT confirmed on ultrasound. The SimpliRED assay was positive in only 33 cases, with seventeen cases of confirmed DVT giving a negative result (six cases with proximal vein thrombosis). Assay sensitivity was 66%, with a negative predictive value of 88.9%. The IL test gave three false negatives (all below knee thromboses) giving assay sensitivity and negative predictive value of 94.1% and 96.8% respectively. CONCLUSIONS: The precise role of d-dimer testing in the diagnosis of venous thrombosis has yet to be established. From our results and a review of published series, we conclude that the SimpliRED assay is too insensitive to use as a reliable exclusion test in cases of suspected DVT, however, the more sensitive automated IL test d-dimer may have a role in the initial assessment. We propose that the IL d-dimer test is used in conjunction with a pre-test probability score to identify patients at low risk of DVT and recommend that this approach is tested in a clinical study before introduction into practice.

Diagnosis, Differential↗
PubMed2001

Early feeding after cesarean: randomized trial.

OBJECTIVE: To study the rate of ileus symptoms and hospital course of women who are offered solid food shortly after cesarean delivery. METHODS: This study involved women delivered by cesarean under regional anesthesia. Exclusion criteria included general anesthesia, magnesium sulfate, intra-operative bowel injury or bowel surgery, or other conditions that precluded early feeding. Early-fed women were offered regular diets within 8 hours of surgery, and controls were given nothing by mouth for 12-24 hours, advanced to clear liquids on the first postoperative day, and then given solid food on the second or third postoperative day. RESULTS: Sixty women were assigned randomly to each method. Early-fed women received solid food sooner after surgery, 5.0 +/- 1.2 hours versus 40.0 +/- 10.6 hours. The incidences of mild ileus symptoms and postoperative complications were similar in both groups; however, the study did not have an adequate sample size to definitively assess safety concerns. Women in the early-fed group had shorter hospital stays (49.5 +/- 12.7 hours versus 75.0 +/- 12.3 hours, P <.001), and shorter time intervals from surgery to bowel movement, 34.5 hours (interquartile range 25.3-48.8) versus 51.0 (43.3-62.0) hours, P <.001. In the early-fed group, women whose operative times exceeded 40 minutes were more likely to have symptoms of mild ileus. CONCLUSION: Early initiation of solid food after cesarean delivery appears to be well tolerated and may be associated with a shorter hospital stay. Early-fed women whose operations exceed 40 minutes may be more likely to have mild ileus symptoms.

Adult↗
PubMed2001

Sjogren's syndrome.

Sjogren's syndrome is a chronic progressive autoimmune disorder manifested predominately by xerostomia (dry mouth) and keratoconjunctivitis sicca (dry eyes). It can also affect many body systems. Up to 5% of people over the age of 60 years have primary Sjogren's syndrome, and approximately one third of patients present with extraglandular (systemic) manifestations. This disease is seen mostly in middle-aged women, with a small but significant proportion of these women developing lymphoid neoplasia. The exact etiology is still unknown. This autoimmune disorder is characterized by B-cell activation, the production of numerous auto-antibodies, and the loss of immune tolerance. Salivary gland biopsy remains the most helpful diagnostic test. Treatment is aimed at moisture replacement, which alleviates the discomfort and slows the destructive process. Because of its prevalence in older women, the obstetrician-gynecologist must be aware of the diagnostic and therapeutic approach to Sjogren's syndrome.

Journal Article↗
PubMed2001

Evaluation of the clinical efficacy of marbofloxacin (Zeniquin) tablets for the treatment of canine pyoderma: an open clinical trial.

The efficacy and field safety of marbofloxacin (Zeniquin) for the treatment of superficial and deep bacterial pyoderma were evaluated. Seventy-two dogs were treated with 2.75 mg kg-1 of marbofloxacin orally once daily for 21 or 28 days. Sixty-two dogs (86%) had superficial pyoderma and 10 (14%) had deep pyoderma. A history of prior pyoderma was reported in 39/72 dogs. Pretreatment aerobic bacteriologic cultures of skin lesions were performed in 47 cases and the predominant pathogen isolated was Staphylococcus intermedius. Treatment was successful in 62/72 (86.1%) dogs, improvement was noted in 6/72 (8.3%) dogs and treatment failed in 4/72 (5.6%) dogs. Adverse effects associated with treatment included listlessness, anorexia, vomiting, soft stool, flatulence and polydipsia; these adverse effects were seen in only 6/81 dogs. Marbofloxacin was safe and effective for the treatment of superficial and deep pyoderma in dogs at the dosage used in this study.

Administration, Oral↗
PubMed2001

Identification of Yersinia-infected blood donors by anti-Yop IgA immunoassay.

BACKGROUND: From 1991 through 1996, nine transfusion-related cases of septicemia and endotoxemia occurred in New Zealand, a rate approximately 80 times that in the United States. Eight cases involved the transfusion of Yersinia enterocolitica-infected blood and one involved Serratia liquefaciens-infected blood. Six of the recipients died. Donor exclusion by recent gastrointestinal illness failed to prevent the four most recent such infections, and it has led to an estimated 3- to 5-percent rate of donor deferral. STUDY DESIGN AND METHODS: An antigen preparation containing the released proteins (Yops) of Y. enterocolitica was used to establish an EIA to detect IgA directed against these proteins in donated blood. The assay was tested with serum from donors in transfusion-related endotoxemia cases, subjects who were stool culture-positive for Y. enterocolitica, and 495 healthy volunteer blood donors. RESULTS: The assay detected anti-Yop IgA in the donors of all 6 infected units tested. Ninety-six percent of culture-positive subjects tested positive, whereas there was 70-percent positivity with a commercial immunoassay based on lipopolysaccharide. Five percent of random donors tested positive; only one of these had Y. enterocolitica present in a stool sample, and none were bacteremic. CONCLUSION: The anti-Yop immunoassay used in this study could be applied to reduce the risk of posttransfusion endotoxic shock caused by Y. enterocolitica.

Bacterial Proteins↗
PubMed2000

The evaluation and treatment of the overweight patient.

Obesity represents one of the most important treatable causes of mortality and morbidity facing the primary care physician. Approximately one of every three U.S. adults is overweight or obese, leading to more than 300,000 preventable deaths each year. Because it is a multifactorial disorder involving food intake, physical activity, metabolism, and genetic factors, obesity is best treated with a coordinated approach. Diet and exercise remain the best initial treatment focus. Orlistat and sibutramine are recently developed medications reserved for obese patients who fail conservative therapy. Surgical remedies are indicated in limited circumstances for morbidly obese individuals. As primary care physicians, obstetrician/gynecologists are ideally positioned to motivate, evaluate, and treat overweight patients.

Journal Article↗
PubMed2000

Sexual dysfunction in the elderly patient.

With the aging population, the primary care physician will frequently encounter elderly patients with sexual dysfunction. The majority of older patients desire to maintain their sexual activity without significant decline. Age-related physiologic changes include the slower progression of the sexual response cycle. Medical illnesses and medications, as well as cultural, societal, and psychological factors, also impact sexual function. Reassurance and counseling about modifications in sexual practices are usually well received. Medical and surgical therapies are also available. Because sexual function represents a vital issue in an individual's quality of life, the obstetrician/gynecologist must be well versed in the evaluation and treatment of sexual dysfunction of the elderly patient.

Journal Article↗
PubMed2000

Anger expression, gender, and ambulatory blood pressure in mild, unmedicated adults with hypertension.

The suppression of anger has been associated with the development of hypertension. This study evaluated the association between anger management style (anger-in and anger-out) and ambulatory blood pressure (ABP) in patients with repeated clinic diastolic blood pressures (DBPs) between 90-105 mmHg, unmedicated and with no known coronary artery disease. A total of 128 men (46.0 years) and 66 women (46.6 years) participated. Fourteen percent of men and 35% of women were classified as having "white coat" hypertension (daytime DBP < 85 mmHg). Mean awake and sleep DBP and systolic blood pressure (SBP) were evaluated in a repeated measures analysis of variance (ANOVA). Anger-in and anger-out scores were categorized into low, medium, and high t-scores (< 50, 50-59, > or = 60). Results indicated that in women, increasing anger-in is associated with greater SBPs while awake and sleeping, whereas no effect was found for DBP, nor any effect in men. No significant association was found between gender, anger-out, and ABP. The clinical diagnostic status of white coat hypertension was not differentially associated with anger-in or anger-out in men and women. In conclusion, in a sample of mild unmedicated adults with hypertension, suppression of anger is associated with greater ambulatory SBP in women, but not in men.

Adult↗
PubMed2000

Neuromuscular paralysis as a pharmacodynamic probe to assess organ function during liver transplantation.

Potential for assessing liver function during liver transplantation surgery by monitoring muscle paralysis from nondepolarizing neuromuscular blockers that are hepatically cleared is critically assessed. Rocuronium is strongly favored as a promising pharmacodynamic probe for predicting allograft liver function because it is predominantly eliminated via the liver and its putative metabolites are not active. Prolongation of recovery from rocuronium paralysis is closely correlated with allograft liver function postoperatively. Vecuronium, pancuronium, and perhaps pipecuronium may also prove to be useful probes, but the two former blockers have active metabolites. Further prospective studies are necessary with more precise measurement of neuromuscular function to confirm the predictive value of this method. Alterations in neuromuscular blocker plasma concentrations that are correlated with changes in liver function and either the dose required or the intensity or duration of paralysis needs to be demonstrated for this technique to be clinically useful.

Androstanols↗