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Biomedical subjects

B Lynch

Publications and source records attributed to B Lynch.

At least 19 recordsLinked to original sources
PubMed1999

Chronic survival of calves implanted with the DeBakey ventricular assist device.

The DeBakey ventricular assist device (VAD) is a miniaturized, electromagnetically driven axial flow pump capable of generating in excess of 10 L/min output. The VAD was evaluated in 19 calves during experiments designed to test iterative modifications in the system and to determine the safety of the DeBakey VAD for intermediate to long-term implant. Five of the animals died or were euthanized during the perioperative period (i.e., Days 1-5) due to complications associated with bleeding (n = 3), sudden cardiac arrest (n = 1), or pump occlusion due to a muscle remnant associated with coring (n = 1). The remaining 14 animals survived from 7-145 days. Ten of the 14 animals survived 30 or more days, and 2 animals survived 93 and 145 days before elective euthanasia. Pump function was evaluated in the 14 calves that survived beyond the perioperative period. Pump output at implantation averaged 3 L/min while output at 100 days (n = 2) averaged 4.22 L/min. The electrical current did not change across time during the study, indicating normal operation of the bearings. Pumps consumed less than 10.5 W of power for all support durations. Hemolysis did not occur; the average daily plasma free hemoglobin varied from 2.0 to 8.0 mg/dl. Evaluation of serum biochemical data showed that implantation of the DeBakey VAD in calves with normal hearts did not impair end organ function; BUN, creatinine, and total bilirubin varied minimally within the normal range. The white blood cell count of implanted animals remained within the normal range throughout the study.

Animals↗
PubMed1996

Long-term outcome of prostatic stent treatment for benign prostatic hyperplasia.

OBJECTIVES: To evaluate the long-term result of prostatic stent treatment for patients with benign prostatic hyperplasia (BPH). METHODS: We reviewed our experience with prostatic stents in 24 patients with bladder outlet obstruction caused by BPH for whom up to 63 months of follow-up data were available. RESULTS: Prostatic stents were successfully placed in 24 of 25 patients enrolled in the study. All 9 patients treated for urinary retention voided spontaneously after stent placement. In 14 (93%) of 15 patients with nonretention, voiding symptoms decreased by 50% or more. The stent was removed in 9 patients for persistence of symptoms, symptom recurrence, or stent migration. Nine patients died of unrelated causes during the follow-up period. The stents functioned adequately in these patients until death. In the remaining 6 patients, the stent was still in place at the last follow-up visit (range 12 to 52 months, average 35) after placement, and their Madsen-Iversen symptom scores ranged from 3 to 10. Fourteen patients underwent cystoscopy 1 to 37 months after stent placement. Epithelium did not completely cover the stent in any of these patients; however, no stone formation was noted. CONCLUSIONS: Prostatic stents can be effective in relieving bladder outlet obstruction caused by BPH. They appear to be most useful in patients at high surgical risk and with a limited life expectancy. However, stent removal, which can be difficult, may be required in more than one-third of patients. We recommend prostatic stent placement primarily in patients who would otherwise be relegated to an indwelling catheter.

Aged↗
PubMed1994

Randomized comparison of balloon dilation and transurethral incision for treatment of symptomatic benign prostatic hyperplasia.

The concept of relieving the symptoms of benign prostatic hyperplasia (BPH) by dilating the urethral has existed for centuries. Thirty patients with a clinically estimated prostate gland size of 25 g or less were randomized to either balloon dilation (BDP) or transurethral incision of the prostate (TUIP). The mean pretreatment Madsen-Iverson symptom scores in the two groups were 15.0 +/- 4.9 (SD) and 15.4 +/- 4.4, respectively. The early response rates were 87% fo BDP and 86% for TUIP, with the mean symptom scores declining to 3.4 +/- 2.8 after dilation and 4.2 +/- 6.6 after incision. Among the 14 patients who initially responded to BDP, 2 have been lost to follow-up, 1 died of unrelated causes at 17 months with no urinary symptoms, 2 remain in response at 32 and 38 months, and the other 9 (75% of those available for evaluation) have developed recurrences. Among the 12 patents who responded to TUIP, 2 have been lost to follow-up, 8 remain in response at 14 to 48 months, and 2 (20%) developed recurrences by 44 months of follow-up. In the short term, both BDP and TUIP are effective for treating bladder outlet obstruction in men with relatively small prostates. However, the effect of dilation appears to be less durable than that of incision.

Aged↗
PubMed1994

Repeat consultations after antibiotic prescribing for respiratory infection: a study in one general practice.

BACKGROUND: Several new antibacterial drugs have been introduced in the last 10 years with the aim of improved treatment of respiratory tract infection. AIM: The study set out to use repeat consultations as a measure of the outcome of antibiotic treatment for respiratory tract infection, and to develop a simple model for discussion of the cost effectiveness of alternative antibiotic treatments. METHOD: All consultations to one practice during a single winter were reviewed by one general practitioner. RESULTS: A total of 1140 patients had acute symptoms suggestive of respiratory infection. Of these, 899 patients (79%) were prescribed antibiotics at the first consultation and 160 of the 899 patients (18%) returned for one or more repeat consultations; only nine repeat consultations were due to adverse effects of the antibiotics prescribed. Only two patients were admitted to hospital for respiratory symptoms following initial antibiotic therapy and both patients had additional reasons for their admission. Using the highest estimates, the cost of a repeat consultation was found to be 28.54 pounds. These data were used to calculate how much more might be spent on more effective antibiotics at the first consultation. It would be difficult to justify increasing the cost of antibiotic treatment by more than 5 pounds per patient, even if the new treatment were 100% effective and all repeat consultations were due to treatment failure (5 pounds is equal to 28.54 pounds x 0.18, which is the maximum cost of a repeat consultation multiplied by the proportion of patients prescribed antibiotics who make repeat consultations). CONCLUSION: From these results and a review of the literature it can be concluded that new antibacterial drugs will have to be carefully targeted if they are to prove cost effective in practice. Other methods for reducing repeat consultation merit investigation.

Adolescent↗
PubMed1993

Quantitative dendritic and spine analyses of speech cortices: a case study.

The present case study documents an unprecedented opportunity for correlative investigation of brain structure and function by quantitatively investigating the basilar dendritic systems of supragranular pyramidal cells in several cortical areas from a subject who had undergone electrical stimulation mapping 2 years prior to death. Electrical stimulation mapping results provided valuable functional information about the cortical areas removed for postmortem histological analysis. Morphometric analyses distinguished between proximal (first, second, and third order) and ontogenetically later developing distal (fourth order and above) basilar dendritic branches. In general, perisylvian language association stimulation sites (classical Wernicke's and Broca's areas) were characterized by different dendritic patterns than motor strip sites. In primary motor strip tissue blocks, proximal segments were longer than distal segments. In "higher order" elaborative cortical zones, distal segments were longer than proximal segments. Proximal segments outnumbered distal segments in primary motor zones, but the numerical difference between proximal and distal segments was reduced in the association areas. Finally, fourth order segments had significantly more dendritic spines than third order segments in all sites. These dendritic findings suggest a somewhat later ontogenetic development in classical Broca's and Wernicke's areas than in primary motor cortex.

Adult↗
PubMed1992

Cost-effectiveness of single dose cefotaxime plus metronidazole compared with three doses each of cefuroxime plus metronidazole for the prevention of wound infection after colorectal surgery.

The cost-effectiveness of prophylaxis for colonic surgery with single dose cefotaxime plus metronidazole has been compared with that of three doses each of cefuroxime plus metronidazole, by analysing data from a previously published study supplemented with additional data on the hospital and community costs of wound infection after colonic surgery. The original trial included 942 patients having elective colonic surgery in 14 hospitals. The data on costs of wound infection were collected from a further 124 patients undergoing elective colonic surgery at Ninewells Hospital. All these patients received a three dose regimen of cefuroxime plus metronidazole. The Dundee patients received three injections of 0.75 g cefuroxime at 8-hourly intervals whereas the trial patients received a single dose of 1.5 g followed by two further doses of 0.75 g at 8-hourly intervals. The cefuroxime prophylaxis regimen used in the trial cost 24.16 pounds per patient more than the cefotaxime regimen. The components of the excess cost were drugs (15.18 pounds), equipment (6.14 pounds) and staff time (2.84 pounds). The median cost to the hospital of a wound infection was 978.04 pounds (95% CI 482.04 pounds to 1521.22 pounds). The components of the hospital cost of wound infection were: hotel costs 858 pounds (88%), dressing costs 83.02 pounds (8%) and drug costs (excluding prophylaxis) 37.02 pounds (4%). Only five patients received additional antibiotic treatment in the community, and only one required home visits from the District Nurse. Applying the difference in costs of prophylaxis as 21 pounds (costs of drugs plus equipment) and the cost per wound infection as 1000 pounds to the observed wound infection rate of 7% in the cefuroxime group, the wound infection rate in the cefotaxime group would have to be 2.1% higher for the two regimens to be equally cost-effective. The probability that such a difference in efficacy exists is 0.088. A model was developed to calculate the probability of equal cost-effectiveness over a range of costs of wound infection.

Anti-Infective Agents↗
PubMed1991

Intrarenal pancreatic cyst.

A case report of intrarenal true cyst of the pancreas is presented. The patient presented with flank pain. Her diabetes and hypertension were well-controlled. The cause of the pain was presumed to be a cystic renal mass, which proved to be of pancreatic origin only after the pathologic confirmation from the nephrectomy specimen.

Adult↗
PubMed1991

Effect of colostral fat level on fat deposition and plasma metabolites in the newborn pig.

The effects of colostral fat level on fat deposition and plasma concentrations of glucose, insulin, and free fatty acids (FFA) were determined in 28 newborn pigs during the first postnatal day. Soon after birth, pigs were allotted to four treatments groups. Group 1 was killed at birth. The remaining pigs were fed intragastrically sow colostrum that contained high (10.2%; HFC), normal (4.8%; NFC) or low (1.0%; LFC) levels of total fat at the rate of 15 to 18 g/kg birth weight at 65- to 70-min intervals. A total of 21 feedings was provided and pigs were killed 1 h after the last feeding. Body fat deposition increased linearly (P less than .01) with the amount of ingested fat by .32 (+/- .04) g per 1-g increase in fat intake. Fatty acid composition of the pigs changed toward that of the colostrum with increased fat in colostrum. More liver glycogen was lost (P less than .01) in pigs given LFC. Plasma concentrations of glucose and insulin were similar in pigs fed HFC and NFC. After the 11th feeding (14 h postnatal), LFC resulted in lower plasma glucose concentrations (P less than .05) than HFC or NFC. Plasma insulin concentrations also were lower in pigs fed LFC. Plasma FFA concentrations remained unchanged in pigs fed LFC but increased with both fat content in colostrum (P less than .05) and time (P less than .05) in the other two groups. Colostral fat plays a major role in the supply of energy and in glucose homeostasis in the neonatal pig.

Adipose Tissue↗
PubMed1990

Late hydrocephalus after arrest and resolution of neonatal post-hemorrhagic hydrocephalus.

This report describes the occurrence of rapid progression of hydrocephalus after discharge from the nursery in four of 48 infants who had had previous arrest of progression of post-hemorrhagic hydrocephalus, and at least partial resolution of ventriculomegaly. This later-onset hydrocephalus occurred at a mean age of seven months; the most consistent presenting clinical feature was rapid head growth. Three of the four infants required a ventriculo-peritoneal shunt and the fourth was treated with acetazolamide, with apparent resolution of the hydrocephalus. Newborn infants with post-hemorrhagic hydrocephalus should be followed carefully throughout the first year for prompt detection of later hydrocephalus.

Cephalometry↗
PubMed1988

Biological properties of two models of calcitonin gene related peptide with idealized amphiphilic alpha-helices of different lengths.

Previous studies on calcitonin gene related peptide (CGRP) have demonstrated that it has the characteristics of an amphiphilic peptide, and from an examination of the sequence, we have proposed that it contains an amphiphilic alpha-helix. We have synthesized two analogues of CGRP which have different lengths of idealized amphiphilic alpha-helical secondary structure. The first model, CGRM-1, has been substituted with residues generating an idealized amphiphilic alpha-helix in the region between residues 8 and 25, equivalent to approximately five turns of an alpha-helix. This peptide is not an agonist in any of our bioassays, but it does bind with low affinity to rCGRP receptors in crude liver membranes. Our second model, CGRM-2, has an idealized amphiphilic alpha-helix between residues 8 and 18, which is equivalent to approximately three turns of an alpha-helix. In an in vitro rat vas deferens assay, this peptide is an agonist with a potency one-fourth that of the native hormone. However, the potency of CGRM-2 in an adenylate cyclase assay is much lower, only 1/140th the potency of CGRP. Both model peptides display amphiphilic characteristics commensurate with their design. We conclude that there is an amphiphilic alpha-helix in rCGRP between residues 8 and 18 and that this helix terminates in the vicinity of residue 18.

Adenylyl Cyclases↗
PubMed1987

Biological and physical properties of a model calcitonin containing a glutamate residue interrupting the hydrophobic face of the idealized amphiphilic alpha-helical region.

2A new calcitonin analogue, model calcitonin III (MCt-III), has been synthesized, and its biological and physical characteristics have been studied. This analogue has an idealized alpha-helix from residue 8-22 with glutamate at position 15 interrupting an otherwise continuous surface of aliphatic side chains (those of leucine residues) on the hydrophobic face of the helix. MCt-III differs from a previous model, MCt-II, only by the substitution Leu15----Glu and is here compared with salmon calcitonin I (sCt-I) and MCt-II to elucidate further the role of the putative amphiphilic alpha-helix in determining biological and physical properties of the hormone. MCt-III shows physical properties intermediate between those of sCt-I and MCt-II, demonstrating the influence of appropriately positioned single residues on properties of amphiphilic structures. In our two biological assays, a brain-binding assay and an in vivo hypocalcemic assay, MCt-III reproduces the sigmoidal dose-response curves of sCt-I; this contrasts with the behavior of MCt-II, which demonstrated unusual dose-response curves in these two assays. MCt-III is almost three times more potent than sCt-I in our hypocalcemic assay; this activity groups MCt-III among the most potent known analogues of sCt-I.

Animals↗