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Biomedical subjects

B Day

Publications and source records attributed to B Day.

At least 55 records · Page 3Linked to original sources
PubMed1985

Long-term monotherapy of angina pectoris with diltiazem.

Eighteen patients with exertional angina were treated with diltiazem (360 mg/day). Serial exercise testing was performed and the results were compared to evaluations when patients were receiving placebo at the initiation and termination of the study. Serial exercise tests indicated significant improvement in duration of exercise (+18%, p less than 0.001), time to 1 mm ST depression (+32%, p less than 0.005), and time to angina (+46%, p less than 0.001) when patients were receiving diltiazem. During diltiazem treatment, there was a significant reduction in myocardial oxygen demand as indicated by the change in submaximal pressure rate product. This may contribute to the beneficial effect of diltiazem in patients with exertional angina. The reduction in pressure rate product was due primarily to a change in heart rate. This study provides evidence that diltiazem is an effective long-term monotherapy for angina; no evidence of drug tachyphylaxis was apparent after a total of 16 months treatment with diltiazem.

Aged↗
PubMed1984

Long-term study of high-dose diltiazem in chronic stable exertional angina.

The efficacy of a calcium slow channel-blocking drug, diltiazem (360 mg/day), was compared to placebo in 15 men with exertional angina during a 21-week study. Symptom-limited exercise testing was used to evaluate the effects of the drug. Analysis of variance indicated the increase in the values of three time-related variables, time to onset of angina, time to onset of 1 mm ST depression, and total duration of exercise, were highly significant (all p less than 0.001). The increase from the second week of placebo to the last week of diltiazem was 4 X 1 minutes for time to angina, 2 X 4 minutes for time to 1 mm ST depression, and 2 X 3 minutes for total duration. In addition, the differences between mean values of these variables for placebo and corresponding diltiazem period at weeks 3 and 4 were significant (p less than 0.01, p less than 0.01, p less than 0.05) and for diltiazem week 20 and placebo week 21 were significant (p less than 0.005, p less than 0.01, p less than 0.005). Weekly angina frequency was reduced from a mean of 17 episodes/week during placebo to one episode/week during diltiazem (p less than 0.001). Submaximal pressure-rate product was reduced significantly during diltiazem (p less than 0.001), and the ECG evidence of myocardial ischemia was reduced by diltiazem at submaximal (p less than 0.02) and maximal exercise (p less than 0.001). The drug was well tolerated and appears to be effective monotherapy for exertional angina.

Aged↗
PubMed1984

Bumetanide and furosemide in heart failure.

We assessed the handling of and response to oral bumetanide (1.0 and 2.0 mg) and to furosemide (40 and 80 mg) in 20 patients with stable, compensated congestive heart failure (CHF), comparing the two drugs and, in addition, examining differences from normal subjects. Bumetanide and furosemide were similar in time course of absorption, but patients with CHF had considerably prolonged absorption compared to normal subjects causing attainment of lower peak concentrations of drug. In both CHF and normal subjects, more bumetanide than furosemide was absorbed. The elimination half-life of furosemide was approximately twice that of bumetanide, and both were about two times longer than respective values in normal subjects. "Dose"-response curves were shifted downward from normal with both drugs. In patients with CHF, overall response did not differ between bumetanide and furosemide. The two drugs exhibit subtle differences, the clinical importance of which appears to be negligible from this study. Importantly, however, both drugs showed delayed absorption causing attainment of peak urinary excretion rates of diuretic two- to threefold lower than in normal subjects. This effect along with the abnormal responsivity of the tubule may contribute to the "resistance" to oral doses of diuretics observed clinically even though no quantitative malabsorption of drug occurs.

Absorption↗
PubMed1984

The iliopsoas muscle pedicle bone graft: an experimental study of femoral head vascularity after subcapital fractures and hip dislocations.

Distal iliopsoas muscle pedicle bone graft was investigated in dogs to determine whether a collateral blood supply to the femoral head can develop after displaced femoral neck fractures and dislocation of the hip joint. Microangiography performed in cadavers showed good vascularity of the muscle pedicle graft and similar studies in dogs showed that when transferred to the anterior femoral neck, the iliopsoas muscle pedicle graft healed with an ingrowth of vessels across the graft site. Microangiographic and histologic studies in dogs showed that the procedure could maintain the vascularity and viability of the grafted femoral head. Consequently, an iliopsoas muscle pedicle bone graft can provide a vascular supply to a compromised femoral head and may be applied in both the prevention and treatment of avascular necrosis of the injured femoral head.

Angiography↗
PubMed1984

Effect of the high femoral osteotomy upon the vascularity and blood supply of the hip joint.

This investigation was done to study the effects of high femoral osteotomy upon the vascularity and blood supply of the hip and to further our knowledge of its physiologic basis. We have used established methods of study, including bone scans, microangiography, isotope clearance and perosseous venography, and based upon the results of these studies, we have reached certain conclusions. First, high femoral osteotomy increases the blood flow and vascularity in the hip joint, the femoral head and neck and the great trochanter. Second, bone scanning techniques using 99mTc labeled diphosphonate have shown increased uptake in the femoral head and neck after high femoral osteotomy. The localization was done using a Digital Gamma III computer, and the activity on the osteotomy side at two weeks was 3.5 times as great as on the control side. By 16 weeks postoperatively, there was still two times as much activity on the osteotomy side. Third, microangiography showed increased vascularity both at the osteotomy site and in the femoral head and neck and the greater trochanter on that side. Such an increase in vascularity first became evident two weeks after osteotomy and persisted during the four month period studied. Fourth, the results of the 99mTc diphosphonate clearance study showed a 25 per cent increase in femoral head blood flow on the operative side. Fifth, perosseous venography of the femoral head and neck showed a marked increase in venous drainage through the osteotomy site in the immediate postosteotomy stage.

Animals↗
PubMed1983

Bumetanide and furosemide.

We assessed the response to and handling of furosemide and bumetanide in 30 experiments with the former and 46 with the latter in normal subjects. Oral doses of furosemide (20, 40, and 80 mg) were used, and subjects received oral doses of 0.5, 1, and 2 mg bumetanide and intravenous doses of 0.5 and 1 mg bumetanide. both drugs were quickly absorbed and peak urinary amounts were reached at 75 min (median). Approximately 30% of an oral dose of each drug was excreted unchanged in the urine with no evidence of dose-dependent elimination. After intravenous injection, 36% of the bumetanide was excreted unchanged. Consequently, bumetanide has an estimated bioavailability of 80% (approximately 40% for furosemide). The relationship between the logarithm of the urinary bumetanide excretion rate and the logarithm of the sodium excretion rate was described by a sigmoid-shaped dose-response curve, with a dose inducing half-maximal response of 1 +/- 0.04 micrograms/min; it was 69.8 micrograms/min for furosemide. Overall, the distinguishing features between the two drugs are the 200% greater bioavailability and the much greater potency of bumetanide.

Administration, Oral↗
PubMed1983

Azosemide kinetics and dynamics.

Azosemide is a loop diuretic that may also affect sodium reabsorption at the proximal tubule. We gave intravenous and oral doses of the drug to normal subjects to examine its kinetic and dynamic parameters. In the fasting state a lag time of absorption of approximately 1 hr was followed by absorption t 1/2s and elimination t 1/2s of approximately 0.75 and 2 2.5 hr. Only 2% of an oral dose was excreted unchanged in the urine. After intravenous dosing the elimination t 1/2 was approximately 2 hr; 20% of a dose was recovered unchanged. Thus azosemide has an estimated bioavailability of 10%. The relationship between urinary azosemide excretion rate ("dose") and natriuretic response follows a sigmoid-shaped curve with a dose inducing half-maximal response of 9.3 +/- 2.6 micrograms/min, whereas it is 69.8, 12.1 and 1 microgram/min for furosemide, piretanide, and bumetanide respectively.

Administration, Oral↗
PubMed1982

The time course of delivery of furosemide into urine: an independent determinant of overall response.

After an oral or intravenous dose of furosemide, there is considerable interindividual variability in the amount of unchanged drug delivered into the urine. On average, approximately half as much reaches the intraluminal site of action with an oral compared to an intravenous dose. However, the natriuretic response to the same dose administered by either route is virtually the same. Similarly, after pretreatment with probenecid, the same total amount of furosemide in urine causes a greater overall response. It has been presumed that this paradox is accounted for by differences in rate of delivery of furosemide to the active site such that after an oral dose, or after pretreatment with probenecid, amounts of drug are for longer periods of time at the "steep" portion of the dose-response curve. Our analysis shows this not to be the case. For furosemide, the "slope factor" of the dose-response curve is such that the amount of diuretic delivered into the urine which is maximally efficient (21.5 micrograms/min) is considerably less than the amount causing half-maximal response (69.8 micrograms/min). Oral administration or pretreatment with probenecid maintains drug close to this maximally efficient amount more persistently than does intravenous administration. By so doing, total response to an oral dose approaches that of intravenous dosing despite delivering half the amount of drug to the active site, and after probenecid an intravenous dose causes a greater response than intravenous dosing alone despite delivering the same amount of drug to the active site. These data emphasize the importance of the time course of delivery of drug to the active site as an independent determinant of overall response.

Administration, Oral↗
PubMed1981

Circulatory and vascular changes in the hip following innominate osteotomy: an experimental study.

The circulatory and vascular changes in the hip following Salter-type innominate osteotomy were studied in 35 dogs to determine the effects of innominate osteotomy on the blood supply of the hip joint. Microangiography, bone scanning, and isotope clearance were employed four months after the innominate osteotomy. Microangiography showed increased vascularity at the osteotomy site, in the ipsilateral side acetabulum, and in the femoral head in 65% of the dogs. Bone scanning with 99mTc diphosphonate showed increased activity at the osteotomy site, in the acetabulum, and in the femoral head and neck in 75% of the dogs. The 99mTc diphosphonate clearance studies showed that the blood supply to the femoral head was increased by almost 30% after innominate osteotomy in 50% of the dogs studied. These observations indicate that innominate osteotomy could increase the vascularity and blood supply of the hip by increasing the collateral circulation in the process of healing of the osteotomy. The physiologic basis of the joint to innominate osteotomy constitutes a rational basis for recommending the operation for the treatment of selected cases of congenital hip dislocation, Legg-Perthes disease of the femoral head, and degenerative osteoarthritis of the hip with or without acetabular dysplasia.

Acetabulum↗
PubMed1980

An ultrastructural study of multifidus muscle in progressive idiopathic scoliosis. Changes resulting from a sarcolemmal defect at the myotendinous junction.

Biopsies of multifidus muscles were procured from patients with idiopathic scoliosis prior to Harrington rod instrumentation. Specimens from both convex and concave sides at the apex of the curve were examined by light and electron microscopy and compared with normal muscle samples. Abnormalities were detected on the concave aspect of the curve and the most dramatic morphological changes were noted at the myotendinous junction. Here a structural defect in the form of discontinuities in the sarcolemmal membranes of some muscle fibres was accompanied by large numbers of intimately-adhering connective tissue cells. Structural disorganization of the associated tendon occurred in conjunction with increased vascularization and with fatty cell and leukocyte infiltration. Further from the myotendon junction, structural lesions appeared more chronic and non-specific subsequent to the incipient sarcolemmal break in the affected muscle fibres. Hypertrophy, atrophy, centralization of nuclei, and disruption of sarcotubular and myofibrillar elements were noted in some muscle cells. While the aetiology of this disorder is unknown, a supposition is made that the primary change is an inherent weakness and subsequent break in the sarcolemma at the myotendon junction. This site is an important clue to the pathogenesis of this disease since it reflects morphological change in rapidly growing tissue occurring at the time of the rapid adolescent growth spurt leading to progression of the scoliotic curve.

Adolescent↗
PubMed1980

Red cell sodium and potassium in hemorrhagic shock measured by lithium substitution analysis.

A new method of measuring intracellular Na and K using Li substitution analysis was applied to a study of red cell Na changes in hemorrhagic shock. Using a rat hemorrhagic shock model, significant changes in red cell Na were found after 2 hours. Red cell Na in shocked animals was significantly higher than in control animals (p less than 0.025). A small decrease in red cell K occurred. There was no intracellular shift of Li. In addition, a fall in plasma Na and a rise in plasma K occurred with progressive shock. In a 2-hour period following retransfusion there was no significant change in cell Na or K, but the plasma Na and K returned toward preshock levels. These results confirm a prolonged and significant impairment of red cell membrane function in shock and suggest that impaired Na-K pump function may be responsible for the changes.

Animals↗
PubMed1979

Bone peg fixation in the treatment of osteochondritis dissecans of the knee joint.

Seventeen patients between 15 and 26 years of age, were treated for osteochondritis dissecans of the knee by bone peg fixation. The fragment is attached with 2 or 3 matchstick-size bone graft taken from the proximal tibia. The average follow-up period was 3.2 years, union of the fragment occurred in all cases, and results were rated excellent or good in 16 of 17 patients. Preservation of the normal contour of the distal femur and stabilization of the osteochondral fragment was achieved. Stimulation of local blood supply by bone grafting may have promoted healing and a second procedure for removal of pins or screws was unnecessary.

Adolescent↗
PubMed1978

Intracellular sodium and potassium changes in vascular smooth muslce during hemorrhagic shock.

The vascular smooth muscle cell sodium and potassium changes occurring in hemorrhagic shock were studied in rats subjected to hemorrhagic shock at 30 millimeters of mercury for a two hour period. A new ion exchange method, based upon the substitution of lithium for extracellular sodium was used to measure the intracellular sodium and potassium. A significant rise in cell sodium and fall in cell potassium levels occurred. These changes suggest that vascular smooth muscle cell membrane function is impaired in hemorrhagic shock. The normal homeostatic vascular responses to hemorrhage may be significantly affected by these changes.

Animals↗
PubMed1977

Compression fractures of the thoracic and lumbar spine from compensable injuries.

Compression fractures of the thoracic and lumbar spine have a worse prognosis than is commonly realized. A study of 142 patients with this type of injury reveals several important features which affect the long term prognosis in these injuries. Severe compression, comminution, disc space narrowing adjacent to the fracture site, a low anatomical level of the fracture site, a low anatomical level of the fracture, and body cast immobilization in those with mild or moderate type fractures, are some of the factors associated with persistent long term back problems.

Adolescent↗