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Biomedical subjects

B Griffin

Publications and source records attributed to B Griffin.

At least 19 recordsLinked to original sources
PubMed1992

Comparative effects of fenoldopam mesylate and nitroprusside on left ventricular performance in severe systemic hypertension.

To compare the effects of fenoldopam (n = 15), a selective dopamine-1 agonist, and nitroprusside (n = 14) on left ventricular (LV) function in severely hypertensive subjects (diastolic blood pressure (BP) greater than 120 mm Hg), both agents were infused to reduce diastolic BP by 40 mm Hg (or less than 110 mm Hg). Indexes of LV systolic and diastolic functions were obtained using gated radionuclide angiography before the initiation of treatment and after targeted BP was achieved. Both fenoldopam and nitroprusside effectively reduced systolic and diastolic BP to target levels. Changes in heart rate, peak filling rate and relative end-diastolic volume were similar with both agents. Baseline ejection fraction increased after infusion of both drugs. The magnitude of the increase in ejection fraction was far greater with fenoldopam than with nitroprusside (+22% vs +8%; p = 0.04), despite a lesser reduction in systolic BP (-12 vs -22%, p = 0.002). Furthermore, the reduction in relative end-systolic volume (-35 vs -20%; p = 0.04), and increase in the ratio of peak systolic pressure to relative end-systolic volume (+43 vs +6%; p = 0.007) were greater after fenoldopam than after nitroprusside. The greater increment in parameters of LV systolic function produced by fenoldopam than by nitroprusside suggests an effect on LV performance that is independent of afterload reduction.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1992

Late (two-year) follow-up after percutaneous balloon mitral valvotomy.

Percutaneous balloon mitral valvotomy (PBMV) compares well with surgical commissurotomy, showing comparable improvement in symptoms and catheterization-proven valve area early after the procedure. This study reports the New York Heart Association class, mitral valve area calculated by echocardiography, and the results of transseptal cardiac catheterization 2 years after PBMV. The data are compared with the status immediately before and after PBMV. Forty-one patients returned to enter the study (mean follow-up time 24 +/- 3 months). All patients were evaluated clinically by the same investigator who had seen them at the time of PBMV. Transseptal cardiac catheterization and echocardiographic analysis (2-dimensional and Doppler echocardiography) were performed on the same day. At follow-up, 17 patients were class I, 20 were class II, and 4 were class III. Although the mitral valve area calculated by cardiac catheterization increased significantly from immediately before to immediately after PBMV there was a decrease in the calculated mitral valve area at 2-year follow-up. Echocardiographic analysis did not show as large an increase in mitral area, immediately after PBMV, and no significant decrease in mitral valve area at 2 years (before PBMV planimetry 1.1 +/- 0.1 cm2; immediately after 1.8 +/- 0.1 [p less than 0.05]; follow-up 1.6 +/- 0.1 [p = not significant compared with immediately after PBMV]). Doppler halftime measurements were similar. PBMV is effective therapy with good midterm results for selected patients with mitral stenosis.

Adult↗
PubMed1992

The prognostic significance of postoperative residual contrast enhancement on CT scan in pediatric patients with medulloblastoma.

The clinical and therapeutic features of 20 patients with medulloblastoma treated at Children's Hospital and Medical Center, Seattle, from 1980 to 1987, were retrospectively analyzed with regard to prognosis. The overall actuarial 5-year survival rate was 63%, with 57% of patients free from recurrence at 5 years. Residual contrast enhancement on CT scans taken immediately postoperatively was associated with a significantly decreased 5-year recurrence-free survival rate; the 5-year recurrence-free survival rate was 100% for those patients without post-operative residual enhancement compared to 41% for those patients with residual enhancement. A high risk group of patients with residual contrast enhancement persisting one year following diagnosis was identified. No patient in this group survived without disease progression. Other factors, including sex, age at diagnosis, evidence of tumor dissemination, or extent of surgical resection as reported by the neurosurgeon, did not significantly influence prognosis.

Adolescent↗
PubMed1992

Phase II evaluation of high-dose intravenous cisplatin for treatment of adult malignant gliomas recurrent after chloroethylnitrosourea failure.

Twenty-one patients with recurrent malignant glioma who had failed prior chemotherapy with nitrosoureas were treated with high-dose intravenous cisplatin on days 1 and 8 of successive 4 week cycles. Fourteen patients were evaluable for response. Four patients showed partial responses; mean time to tumor progression (MTP) was 8 weeks. Six patients stabilized; MTP was 11 weeks. Four patients showed no response. There were no infectious or hemorrhagic complications, but partial hearing loss occurred in 7 patients and severe vomiting in 8 patients. High-dose intravenous cisplatin demonstrates substantial activity against malignant gliomas recurrent after chloroethylnitrosourea (CENU) failure.

Adult↗
PubMed1992

Left atrial V waves following mitral valve replacement are not specific for significant mitral regurgitation.

Left atrial or pulmonary capillary wedge pressure V waves are used immediately after mitral valve replacement to evaluate valve competence. However, their correlation with hemodynamically significant regurgitation has not been established. Transesophageal echocardiography (TEE) was used to prospectively examine whether left atrial V waves represented significant mitral regurgitation in 11 patients undergoing mitral valve replacement. Left atrial pressure V waves were measured in the immediate postcardiopulmonary bypass period by direct cannulation of the right superior pulmonary vein and recorded on a paper chart recorder. In each patient, three evaluations of mitral regurgitation by Doppler TEE were made at 15-minute intervals. In 22 of 33 evaluations, left atrial V waves with peak V wave height more than 5 mm Hg above the mean left atrial pressure were present. However, only in 3 of these periods did transesophageal echocardiography show evidence of more than trace mitral regurgitation by pulsed Doppler and color flow mapping. As indicators of mild-to-severe mitral regurgitation diagnosed by TEE, left atrial V waves had a specificity for the three evaluation periods of 40%, 30%, and 40%. Left atrial V waves with peak height greater than 5 mm Hg above mean left atrial pressure frequently appear following mitral valve replacement, but these V waves are nonspecific signs of mitral regurgitation.

Aged↗
PubMed1992

Pharmacokinetics and efficacy of structurally related spirohydantoin and spirosuccinimide aldose reductase inhibitors.

1. Six potent aldose reductase inhibitors (ARI), three spirohydantoin (I to III) and three spirosuccinimide (IV to VI) compounds, showed similar IC50 activities in vitro for the inhibition of rat lens aldose reductase, but their ED50 values in diabetic rats varied as much as 20-fold in the lens and 50-fold in the sciatic nerve tissue. Pharmacokinetic studies were undertaken to investigate these findings. Structure-pharmacokinetic relationships were studied following i.v. administration to cynomolgus monkeys. 2. The clearance (CL) of each spirosuccinimide ARI was faster (greater than 5 times) than that of the corresponding spirohydantoin compound. In both series the CL values of the C(4) methyl and methoxy analogues were 4-fold greater than those for the unsubstituted compounds, although the CL values of the methoxy and methyl derivatives in the same series were not significantly different. 3. The volumes of distribution (Vss) of the spirohydantoins were about one-half those of the corresponding spirosuccinimides, and the Vss values of the parent compounds of both ARI series did not differ dramatically from those of their methyl and methoxy analogues. 4. All six compounds were eliminated from plasma in a biexponential fashion. The half-lives (lambda 1 and lambda 2) of the spirohydantoin compounds were much longer than those of the corresponding spirosuccinimide compounds, and the unsubstituted compounds had longer half-lives than their methyl and methoxy derivatives. The longest lambda 1 and lambda 2 half-lives were observed for imirestat, while two of the spirosuccinimides had the shortest half-lives. 5. These results indicate that the relationships observed between the in vitro and in vivo activities of the six ARI can be attributed to structurally dependent differences in metabolic clearance.

Administration, Oral↗
PubMed1991

Prevalence of unsuspected mitral regurgitation and left ventricular diastolic dysfunction in patients with coronary artery disease and acute pulmonary edema associated with normal or depressed left ventricular systolic function.

To define the prevalence and role of left ventricular (LV) systolic dysfunction, LV diastolic dysfunction and mitral regurgitation (MR) in patients with acute pulmonary edema, 40 patients with coronary artery disease and acute pulmonary edema were prospectively evaluated within 36 hours of presentation. LV ejection fraction and 3 parameters of LV diastolic function were measured with radionuclide ventriculography, whereas MR was assessed with Doppler echocardiography. LV ejection fraction was normal in 11 (27%) and depressed in 29 (73%) patients. Moderate or severe MR without LV diastolic dysfunction was common and equally prevalent in patients with and without LV systolic dysfunction (33 vs 38%; difference not significant). Diastolic dysfunction without MR was less frequent but equally prevalent in patients with and without systolic dysfunction (17 vs 27%; difference not significant). Two (18%) of 11 patients without and 12 (33%) of 36 patients with LV systolic dysfunction had both MR and LV diastolic dysfunction. Furthermore, MR was clinically silent and unsuspected in two-thirds of all patients with MR, regardless of a normal or depressed systolic function. These data show that there is a high prevalence of unrecognized moderate to severe MR in patients with acute pulmonary edema, regardless of the presence or absence of LV systolic dysfunction. Furthermore, the prevalence of LV diastolic dysfunction without MR is relatively low even in patients with normal LV systolic function and pulmonary edema. Thus, unrecognized MR may be an important contributor to the syndrome of acute pulmonary edema in patients with normal or depressed LV systolic function.

Aged↗
PubMed1991

Results of neutron radiosurgery for inoperable arteriovenous malformations of the brain.

Twenty patients with inoperable arteriovenous malformations (AVMs) of the brain were treated with neutron radiosurgery. A 50 MeV cyclotron was used to deliver 9 Gy in a single fraction through 7 to 14 isocentric portals. The size and shape of the portals were customized to each treatment site. Nineteen patients have been followed for a median duration of 24 months following neutron radiosurgery. A radiographically demonstrable partial response was seen in 8 patients (42%). No complete responses were observed. There has been one post-treatment hemorrhage, no fatalities, and no evidence of radiation toxicity. The low response rate and absence of toxicity suggest that the appropriate dose for neutron radiosurgical treatment of AVMs is higher than the dose of 9 Gy at isocenter used in this initial study.

Adult↗
PubMed1991

Interaction of heparinoids with platelets: comparison with heparin and low molecular weight heparins.

Heparin interacts with platelets to impair collagen-induced aggregation and adhesion to collagen. Low molecular weight heparin and heparinoids have little or no inhibitory activity in these platelet-collagen interactions. Thrombin-induced aggregation of platelets is inhibited by any of the glycosaminoglycans that will block the action of thrombin on fibrinogen. However, heparin is a much more potent inhibitor than low molecular weight heparins or heparinoids at equigravimetric concentrations in these reactions. The inhibition of ristocetin or asialo-von Willebrand factor aggregation of platelets is partially blocked by high dose heparin but not by low molecular weight heparin or heparinoids. The heparin-induced IgG antibody, produced to a heparin-platelet complex, aggregates platelets strongly in the presence of heparin, less strongly in the presence of low molecular weight heparins and pentosan polysulfate and not at all with dermatan sulfate or the pentasaccharide. Heparan sulfate does interact with platelets and this antibody, which is of interest because of the heparan sulfate on endothelial cells. Clinical information to date suggests a low incidence of heparin antibodies in patients receiving only low molecular weight heparin of the depolymerized type. Whether long-term clinical use of low molecular weight heparins, heparan sulfate, and dermatan sulfate will give rise to specific antibodies that would cause a similar problem as heparin remains to be seen.

Autoantibodies↗
PubMed1991

Infants with medulloblastoma: a single institution review of survival.

Although the prognoses of children with medulloblastoma have improved dramatically over the last several decades, the reported survival for very young children with this tumor remains poor. We undertook a retrospective review of patients less than 36 months of age at the time of the diagnosis of a medulloblastoma who were treated at our institution during a 36-year period. Of 28 such patients, 10 patients are presently surviving without disease at a median of 150 months from diagnosis. The presence of a metastatic tumor at the time of diagnosis was identified as a significant indicator of a poor prognosis, and all completely staged patients without metastasis are surviving without a recurrence of disease. This report suggests that the survival of very young children with a medulloblastoma may not be as poor as has been previously reported, particularly if a disseminated tumor is not present at the time of diagnosis.

Cerebellar Neoplasms↗
PubMed1990

Comparative effects of propranolol and diltiazem on systolic and diastolic left ventricular function in essential hypertension.

The effects of propranolol and diltiazem on left ventricular systolic and diastolic function in hypertensive subjects (DBP 90-114 mmHg) were examined with M-mode and 2D echocardiograms in 21 patients in a double-blind fashion prior to and after 4 months of treatment. Systolic function was assessed by measurement of fractional shortening, mean velocity of fibre shortening, peak systolic pressure/end systolic dimension ratio, and end systolic stress/end systolic dimension ratio. To assess diastolic function, maximal rate of change in left ventricular dimension (MAXD), maximal rate of change in posterior wall thinning (MAX PWT) and early diastolic (EDD) and late diastolic dimension changes (LDD) were calculated using digitised M-mode images of mid-wall diameter. Both propranolol and diltiazem reduced systolic and diastolic pressures similarly. No significant changes were observed in any of the parameters of systolic function with either drug. Similarly neither propranolol nor diltiazem altered MAXD or EDD significantly. Although changes in maximal rate of posterior wall thinning (MAX PWT) were not significant with either drug, diltiazem improved MAX PWT in 7 of 8 patients. The results of the study demonstrate that both propranolol and diltiazem reduce blood pressure without significant deleterious effects on systolic or diastolic function. Diastolic functional parameters, which were not abnormal at baseline, showed no consistent change with either propranolol or diltiazem.

Blood Pressure↗
PubMed1989

Fast neutron teletherapy in advanced epidermoid head and neck cancer. A review.

An extensive review of clinical studies employing fast neutron teletherapy for advanced epidermoid carcinomas of the head and neck is presented. Head and neck tumors have represented an excellent study site because of their accessibility to physical examination for measurement of tumor response, and because early neutron beams have had poor depth dose characteristics, making the treatment of more deeply seated tumors technically difficult. A summary of the major trials comparing neutron and mixed-beam (combination neutron and photon) therapy with conventional therapy indicates no conclusive evidence of improvement in local control or survival rates for the experimental arms. Exceptions to this are the Hammersmith experience and the slightly higher lymph node control rates seen in two studies. An evaluation of toxicity indicates that with the new generation of cyclotrons, complication rates may approach parity with those of photon linear accelerators.

Carcinoma, Squamous Cell↗
PubMed1989

Fast neutron radiation for inoperable and recurrent salivary gland cancers.

The current standard treatment of salivary gland cancers consists of surgical resection, with or without postoperative low linear energy transfer (LET) radiation, resulting in high locoregional control rates. However, tumor control prognosis is poor when conventional radiation is used alone for advanced, inoperable cases. An extensive review of the world's literature on fast neutron irradiation for inoperable, unresectable, or recurrent malignant salivary gland neoplasms is presented and compared with the experience using conventional low LET radiotherapy. The pooled data indicate a locoregional control rate of 67% for fast neutrons versus 25% for photons and/or electrons in the treatment of such advanced disease. The radiobiological rationale supporting this observed increase in tumor control is discussed. The overall significant late complication rate is 19%, but several suboptimal treatment factors were present that contributed substantially to the reported toxicity. With the modern machines and treatment techniques now available, the evidence overwhelmingly supports the role of fast neutron radiation as the treatment of choice for inoperable and recurrent salivary gland cancers.

Energy Transfer↗
PubMed1989

In vitro studies of the interaction of heparin, low molecular weight heparin and heparinoids with platelets.

Heparin, low molecular weight heparins, and heparinoids were studied for their ability to inhibit the aggregation of platelets by various agonists and for their ability to adhere to collagen. Heparin was a very effective inhibitor of aggregation with collagen and with ristocetin as it was with adhesion to collagen. The heparinoids showed little effect on aggregation or adhesion. Heparan sulfate and pentosan polysulfate did show slight inhibitory activity against collagen aggregation and adhesion and both interacted with the antibody induced by heparin therapy. It is of interest that dermatan sulfate and the pentasaccharide were almost inert in these experiments, and are unlikely to induce bleeding by inhibition of platelet function. It is highly probable that interference with the interaction of von Willebrand factor with platelets and collagen is a major mechanism for bleeding in the heparinized patient.

Adenosine Diphosphate↗
PubMed1988

Caring for Joe.

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Aged↗
PubMed1988

Studies on the procurement of blood coagulation factor VIII. In vivo studies on blood components prepared in half-strength citrate anticoagulant.

To determine the viability of blood cells collected in half-strength (0.5 CPD.A2) and full-strength citrate anticoagulants, paired crossover autologous survival studies were performed in normal volunteers using 51Cr-labelled red cells after 35 days storage and 111In-labelled platelets after 5 days storage. For both studies, viability was better maintained in 0.5 CPD.A2 anticoagulant. This was significant for red cells (24-hour survival: 80 +/- 6 vs. 52 +/- 21%) but not for platelets by either linear or multiple-hit models (recovery 51 +/- 13 vs. 38 +/- 14%, survival 5.1 +/- 1.4 vs. 3.7 +/- 1.5 days). The poor viability of red cells after storage in full-strength anticoagulant was associated with low cellular adenosine triphosphate levels and was confirmed in follow-up studies.

Adenine↗