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Biomedical subjects

R Thomas

Publications and source records attributed to R Thomas.

At least 487 records · Page 27Linked to original sources
PubMed1991

Growth of tracheal anastomoses: advantage of absorbable interrupted sutures.

Growth of the trachea after complete transection and anastomosis was studied in four groups of 1-month-old New Zealand white rabbits. The trachea was transected at the fifth cartilaginous ring and then anastomosed with continuous 6-0 polypropylene (Prolene) (group 1), interrupted 6-0 polypropylene (group 2), continuous 6-0 polydioxanone (PDS) (group 3), or interrupted 6-0 PDS (group 4). The animals were followed up for 90 to 103 days (mean follow-up, 95 days). At the time the animals were killed, body weight had increased 125% (1.2 to 2.7 +/- 0.18 kg). Growth of the trachea was assessed at the time of death. Results from this study suggest that growth of a tracheal anastomosis is retarded in a growing animal model. The degree of resultant stenosis was significantly less when an absorbable suture material (PDS) and an interrupted suturing technique were used.

Anastomosis, Surgical↗
PubMed1991

Noninvasive acceleration measurements to characterize the pharyngeal phase of swallowing.

Swallowing disorder (dysphagia) presents a major problem in the rehabilitation of stroke and head injured patients. In the present investigation, a new technique is developed for noninvasive assessment of the pharyngeal phase of the swallowing mechanism. Acceleration was measured with two ultra-miniature accelerometers placed on the skin over the throat. Simultaneously, the swallow suction pressure was monitored. Swallowing in normal individuals gave rise to a characteristic acceleration pattern which was quite reproducible, and was in phase with the swallow pressure. In dysphagic patients, the acceleration response was either absent or significantly delayed. The accelerometry technique provides a tool for continuing patient assessment and demonstrating the clinical improvements.

Biomechanical Phenomena↗
PubMed1991

The use of extracorporeal shock wave lithotripsy in patients with aortic aneurysms.

Extracorporeal shock wave lithotripsy (ESWL*) has revolutionized management of most patients with urolithiasis. The effect of ESWL on patients with an aortic aneurysm is unknown and its safety is questioned by the absence of any case reports in the urological literature. A 68-year-old man with an abdominal aortic aneurysm underwent successful ESWL using the Medstone STS 1050 lithotriptor for right renal calculi. Continuous monitoring of the aneurysm was done using real-time ultrasound during the ESWL treatment. Careful preoperative evaluation in conjunction with appropriate intraoperative and postoperative monitoring makes ESWL management of patients with associated aortic aneurysm possible.

Aged↗
PubMed1991

Renin production after experimental extracorporeal shock wave lithotripsy: a primate model.

Since the advent of extracorporeal shock wave lithotripsy (ESWL) concern has surfaced as to the long-term risk of the development of hypertension, as well as risk to the developing kidney. To study this concern 8 infant and 3 adult rhesus monkeys (Macaca mulatta) underwent treatment with the XL1 experimental lithotriptor to 1 kidney varying the amount of voltage and shocks. Followup consisted of measurement of renin levels and quantitative renal scans, using 131iodine hippurate to calculate effective renal plasma flow. In the infants a slight change was noted in the absolute effective renal plasma flow of the treated kidney versus the untreated side but it was not statistically different. When indexed to body surface area in the growing animal, there was a statistically significant decrease in renal function. However, peripheral renin levels were markedly elevated in the infants at 3 weeks, and they gradually declined during the 6-month period, although levels remained elevated over baseline. The adults also had central renin levels drawn from the renal vein on the treated side, and there was a close correlation with the peripheral levels, which peaked at 3 weeks and returned to normal. Thus, it seems that at least in the short term renin production is increased in infants more than adults. This finding may be an indicator as to renal damage and is a possible explanation for hypertension occurring after ESWL.

Animals↗
PubMed1991

Extracorporeal shock wave lithotripsy: an outpatient procedure.

At many centers circumstances have dictated that extracorporeal shock wave lithotripsy (ESWL*) be performed on an outpatient (that is same-day surgery or 1-day stay) basis. At our center, Louisiana Lithotripter, Inc., which is a privately owned ESWL unit located at Tulane University Hospital, we have had the opportunity to treat patients in the inpatient and outpatient setting since inception. Since our first ESWL treatment on December 18, 1985 we have treated more than 2,500 patients. Additionally, our unit was named an American Urological Association Training Center in October 1986, resulting in more than 200 urologist, nurse and technician trainee visits. The first 1,779 cases through December 31, 1988 have been thoroughly reviewed. The rate of outpatient ESWL has increased from 22% of the first 100 cases to more than 90% of the last 100. The cumulative over-all rate reached 70%. Currently, more than 95% of our cases are planned as same-day procedures. Safe and effective outpatient ESWL is able to be performed with first generation technology, paving the way for appropriate clinical application to newer technological modalities.

Ambulatory Care↗
PubMed1991

Thrombotic thrombocytopenic purpura with the acquired immunodeficiency syndrome: a pathologically documented case report.

We report a patient with the acquired immunodeficiency syndrome (AIDS) in whom the acute onset of neurologic disorders and renal failure could be attributed to thrombotic microangiopathy. Clinical, biological, and pathological features were compatible with the diagnosis of thrombotic thrombocytopenic purpura (TTP). Such cases have been previously described, but histologically documented case reports are uncommon.

AIDS Dementia Complex↗
PubMed1991

Fluvoxamine and alcoholism.

There has been much recent interest in the pharmacological manipulation of alcohol intake and alcohol seeking behaviour. An effective drug treatment could form an important part of a multi-modal treatment programme and could make controlled drinking more of a reality. In animal models the serotonin reuptake inhibitors, including fluvoxamine, have been consistently shown to reduce alcohol consumption, even in alcohol-preferring rat strains. Clinical studies have shown that these specific serotonin reuptake inhibitors may also be useful in significantly reducing the alcohol intake of a group of early stage problem drinkers. Although there are many possible mechanisms, the most likely mechanism to explain this mode of action of these specific serotonin antidepressants is that the serotonin enhancement they produce reduces the positive reinforcement properties of alcohol and thereby produces an anti-craving effect. These studies now need to be replicated, with particular attention being given to those patients who fulfil the criteria of the alcohol dependence syndrome. Such an ongoing study with fluvoxamine will be described.

Alcohol Drinking↗
PubMed1991

Corneal hazards in use of Simmons shell.

A Simmons tamponade shell was used in 10 cases of post-trabeculectomy overfiltration leading to shallow (iridocorneal touch) or flat anterior chamber. The Simmons shell was an unqualified success in only three cases. Corneal abscess (one case) and corneal abrasion/epithelial loss (four cases) necessitated premature removal of the shell. Three of the patients with corneal abrasions had a formed anterior chamber at the time of shell removal but this shallowed again within 12 hours. Two of these required surgical reformation of the anterior chamber and one reformed spontaneously. Air entrapment causing corneal dessication was probably responsible for the abrasion/epithelial loss. The patient who developed a corneal abscess was grossly malnourished. Use of the Simmons shell needs close monitoring and it should be removed at the first sign of corneal toxicity (abrasion/epithelial loss). Extreme care is necessary in malnourished cases.

Adolescent↗
PubMed1991

P300 and reaction-time measures in senile dementia of the Alzheimer type.

Auditory evoked potentials were recorded in a choice reaction-time task. This test paradigm elicited the attention-related P300 component and was used to study cognitive processing. Compared with age-matched controls, 17 patients with dementia of the Alzheimer type were shown to have significantly longer reaction times as well as delayed latencies of several components of the auditory evoked potentials. The fractional increase in the reaction times was much greater than that of the P300 peak latency. The latter is commonly accepted as an index of stimulus-evaluation time. These findings suggest a delay in both response selection and stimulus evaluation.

Aged↗
PubMed1991

Effect of increased training volume on blood lipids and lipoproteins in male collegiate swimmers.

This study was conducted to assess whether a previously described dose-response relationship between the amount of exercise and the magnitude of change in blood lipid and lipoprotein levels is observed with large volumes of exercise in young, healthy individuals. Blood lipid and lipoprotein levels were monitored during a 25-wk season of training and competition in experienced male collegiate swimmers, who were divided into two groups matched for swimming skill. After an initial 4-wk conditioning period for both groups, one group (N = 11) underwent a 6-wk period during which their training volume was increased from 22,000 m.wk-1 to 44,000 m.wk-1. The other group (N = 13) maintained their swimming distance at 22,000 m.wk-1 during this period. During the remaining 15 wk of the season, both groups swam approximately 22,000 m.wk-1. Swimmers' body weights did not change over the season, but body fat decreased significantly (P less than 0.01). No changes in HDL cholesterol were observed during the season in either the increased training or the regular training groups. Total and LDL cholesterol levels were lower at 20 wk than at the start of the study, but final levels did not differ from initial levels. Thus, the volume of swimming exercise may not be related to the degree of change in blood lipid and lipoprotein levels in healthy subjects with high activity levels.

Adult↗
PubMed1991

Growth and cell viability of aortic versus pulmonic homografts in the systemic circulation.

Growth characteristics and cell viability of aortic and pulmonic valve homografts in the systemic circulation were compared in a growing sheep model. Seven aortic and seven pulmonic cryopreserved homografts were implanted in the descending aortae of recipient female lambs. Of seven sheep per group, three were killed at 8 months, three at 12 months, and one at 15 months. Tissue cultures were obtained on homograft valve and root wall specimens. Male donor cells were identified by chromosome analysis. Preimplant to explant changes in pulmonic homograft external diameters at the valve annulus and sinotubular junction increased significantly more than in aortic roots. The postoperative dimensions of the distal anastomotic diameter and length of the graft increased significantly more in pulmonic than in aortic roots by time of explant. Leaflet calcification and valvular stenosis did not develop in either pulmonic or aortic homografts over the period of observation. Calcification in the root wall was significantly less in pulmonic than aortic homografts. Growth on tissue culture was obtained from over 70% of homograft specimens. Viable donor cells were demonstrated in none and 43% of aortic and pulmonic leaflets, respectively, and 71% and 57% of aortic and pulmonary arterial homograft walls, respectively. In conclusion, both aortic and pulmonic homograft valves provide freedom from calcification and stenosis in this model. Continuing expansion of pulmonic root diameters under systemic pressure might lead to late aneurysm formation. Although host cell repopulation of grafts may be advantageous, the presence of viable donor cells in leaflet tissue does not seem necessary to prevent calcific degeneration.

Animals↗
PubMed1991

Adaptations to swimming training: influence of training volume.

In an effort to assess the contributions of a period of increased training volume on swimming performance, two matched groups of collegiate male swimmers were studied before and during 25 wk of training. For the first 4 wk of this study, the two groups trained together in one session per day for approximately 1.5 h.d-1. During the following 6 wk (weeks 5-11), one group (LONG) trained two sessions per day, 1.5 h in the morning and 1.5 h in the afternoon. The other group (SHORT) continued to train once each day, in the afternoon with the LONG group. Over the final 14 wk of the study, both groups trained together in one session per day (1.5 h.d-1). Although the swimmers experienced significant improvements in swimming power, endurance, and performance throughout the 25 wk study, there were no differences between the groups. However, during the 6 wk period of increased training, the LONG group experienced a decline in sprinting velocity, whereas the SHORT group showed a significant increase in sprinting performance. The test results suggest that a 6 wk period of two 1.5 h training sessions per day does not enhance performance above that experienced with a single training session of 1.5 h each day. It was also noted that both groups showed little change in swimming endurance and power after the first 8 wk of training, though their performances improved significantly after each taper period.

Analysis of Variance↗
PubMed1990

Bone acidic glycoprotein-75 is a major synthetic product of osteoblastic cells and localized as 75- and/or 50-kDa forms in mineralized phases of bone and growth plate and in serum.

Anti-peptide and anti-protein antisera were produced which both recognize bone acidic glycoprotein-75 (Mr = 75,000) and an apparent fragment or biosynthetic intermediate (Mr = 50,000) in calcified tissues and/or serum. A fragment-precursor relationship is suggested from the fact that closely spaced doublet polypeptides of Mr = 50,000 could be produced by proteolysis of the purified protein upon long term storage. No reactivity was detected with osteopontin, bone sialoprotein, or small bone proteoglycans. Bone acidic glycoprotein-75 represents 0.5-1% of the total radiolabeled proteins synthesized by explant cultures of neonatal calvaria or growth plate, by calvarial outgrowth cultures, and by rat osteosarcoma cells. Amounts produced by explant cultures and calvarial outgrowth cultures were similar to that for osteopontin, a major product of osteoblasts. In osteosarcoma cultures, 80% of labeled antigens were associated with the cell layer fraction wherein specific immunoprecipitation pelleted Mr = 50,000 and 75,000 sized antigens. Bone acidic glycoprotein-75 (Mr = 75,000) is enriched in 4 M guanidine HCl/0.5 EDTA extracts of neonatal rat bone and growth plate tissues, whereas largely absent from heart, lung, spleen, liver, brain, and kidney. Explant cultures of these noncalcifying tissues also synthesized bone acidic glycoprotein-75 antigen, but the quantities produced were only 5% or less that obtained with calvaria. By immunohistochemistry, antigenicity is associated with the bony shaft and calcified cartilage of long bones, but is absent from associated soft tissues. These finding demonstrate that bone acidic glycoprotein-75 is antigenically distinct, predominantly localized to calcified tissues, represents a major product of normal osteoblastic cells and may undergo a characteristic fragmentation in vivo and in vitro.

Animals↗
PubMed1990

[Prevalence, significance and therapy of premature LH rise and peak in the In Vitro Fertilization program].

The incidence of the premature LH-rise/peak has been analysed in view to the pregnancy rate in 139 HMG and combined Buserelin + HMG cycles of an IVF-ET/GIFT program. A premature LH-rise/peak seems to be correlated with a lower pregnancy rate; therefore the cancellation of the stimulation is recommended in these cases. A gonadotropin suppression by the GnRH-analog Buserelin before and during the HMG treatment proved to be a good method to prevent a premature LH-rise/peak and to decrease the number of cancelled stimulation cycles.

Chorionic Gonadotropin↗