PubMed Health⌕ Search

Biomedical subjects

J R Peterson

Publications and source records attributed to J R Peterson.

12 recordsLinked to original sources
PubMed1992

Copyrine alkaloids: synthesis, spectroscopic characterization, and antimycotic/antimycobacterial activity of A- and B-ring-functionalized sampangines.

Several A- and B-ring-substituted sampangines were synthesized and evaluated for antifungal and antimycobacterial activity against AIDS-related opportunistic infection pathogens. Electrophilic halogenation provided a channel for structural elaboration of the sampangine B-ring at position 4, while the synthesis of A-ring 3-substituted sampangines and benzo[4,5]sampangine (24) were achieved from the corresponding functionalized cleistopholines. Two-dimensional NMR spectroscopy was used to rigorously characterize the A- and B-ring substituent patterns. Structure-activity relationship studies revealed the activity of the sampangines was enhanced by the presence of a substituent at position 3 or by a 4,5-benzo group.

AIDS-Related Opportunistic Infections↗
PubMed1991

X-ray structure and crystal lattice interactions of the taxol side-chain methyl ester.

A colorless, parallelepiped crystal of methyl (2R,3S)-N-benzoyl-3-phenylisoserinate belonging to the space group P2(1) with a = 5.414(4), b = 7.813(1), c = 17.802(7) A, beta = 90.87(4) degrees, Z = 2, V = 752.9 A3, Dcalc = 1.32 g cm-3, and mu calc = 1.02 cm-1 was selected and the structure solved using direct methods. Refinement led to a final R = 0.079 for 819 [Fo greater than or equal to 5 sigma (Fo)] reflections. Intermolecular hydrogen-bonding interactions are prevalent in the crystal lattice of this compound.

Alkaloids↗
PubMed1989

Platelet activating factor antagonist design. 3. X-ray crystal structure and intermolecular crystal lattice interactions of methyl trans-4-acetoxymethyl-4,5-dihydro-2,5-bis(3,4-methylenedioxyphenyl)- 3-furancarboxylate.

C23H20O9, Mr = 440.41, monoclinic, P21/c, a = 11.433 (1), b = 7.808 (2), c = 23.313 (3) A, beta = 99.67 (1) degree, V = 2052 A3, Z = 4, Dx = 1.43 g cm-3, lambda(MoK alpha) = 0.71073 A, mu = 0.69 cm-1, F(000) = 920, T = 293 K, final R = 0.048 for 1645 observed [Fo greater than or equal to 5 sigma(Fo)] reflections. The observed structure reveals a trans relationship for the 4-acetoxymethyl and 5-aryl substituents. The 4,5-dihydrofuran ring system adopts an envelope conformation. There is no crystallographically imposed symmetry. Several intermolecular van der Waals interactions occur in the cell lattice of this compound.

Chemical Phenomena↗
PubMed1989

Platelet activating factor antagonist design. 2. X-ray structure of dimethyl 2,3,4,5-tetrahydro-5 beta-(3,4-methylenedioxyphenyl)-2-oxo-3 beta-(3,4,5-trimethoxybenzoyl)-3 alpha,4 alpha-furandicarboxylate.

C25H24O12, Mr = 516.46, triclinic, P-1, a = 8.780 (3), b = 11.298 (4), c = 13.271 (6) A, alpha = 71.77 (4), beta = 70.31 (3), gamma = 72.66 (3) degrees, V = 1189 A3, Z = 2, Dx = 1.44 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 0.74 cm-1, F(000) = 540, T = 293 K, final R = 0.046 for 2495 observed [Fo greater than or equal to 5 sigma (Fo)] reflections. The observed structure reveals a trans disposition for the methoxycarbonyl and aryl substituents at positions 4 and 5 of the heterocycle and a cis-3,4-bis(methoxycarbonyl) relationship. There is no crystallographically imposed symmetry. Several intermolecular van der Waals interactions occur in the cell lattice of this compound.

Chemical Phenomena↗
PubMed1989

Platelet activating factor antagonist design: structure of methyl trans-5-(3,4-dimethoxyphenyl)-2,3,4,5-tetrahydro-2-oxo-4- furancarboxylate.

C14H16O6, Mr = 280.28, monoclinic, P2(1)/c, a = 6.070 (2), b = 9.526 (5), c = 22.418 (5) A, beta = 94.32 (2) degrees, V = 1293 A3, Z = 4, Dx = 1.44 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.71 cm-1, F(000) = 592, T = 293 K, final R = 0.043 for 1400 observed [F0 greater than or equal to 5 sigma(F0)] reflections. The observed structure confirms a trans stereorelationship for the two substituents and an envelope conformation for the lactone ring. There is no crystallographically imposed symmetry. An analysis of the closest contacts in the cell lattice reveals two types of intermolecular interactions for this compound.

Chemical Phenomena↗
PubMed1989

Fever, bacteriuria, and pyuria in spinal cord injured patients with indwelling urethral catheters.

Little is known about the significance of pyuria in spinal cord injury patients with indwelling urethral catheters (IUCs). The hospital courses of 32 such patients admitted to a rehabilitation hospital from January 1986 to December 1987 were reviewed to determine the incidence of unexplained febrile episodes, ie, no obvious nonurinary source of infection. All patients had positive admission urine cultures (greater than 100,000 colony-forming units/mL). Patients were divided into two groups based on the level of pyuria in admission urinalyses. Group A (the low pyuria group) was composed of 22 patients with less than or equal to 50 white blood cells per high-power field (WBC/HPF). Group B (the high pyuria group) was composed of ten patients with less than 50 WBC/HPF. None were admitted to the rehabilitation program taking antibiotics; none were prophylactically treated for urinary tract infection. The difference in incidence of fever between febrile episodes. Group B had an incidence of 6/10 (60%) febrile episodes. The difference in incidence of fever between the groups was statistically significant (chi2 = 7.31, p less than .01). These results suggest that SCI patients with IUCs and gross pyuria may be at risk for increased morbidity secondary untreated urinary tract infection.

Adolescent↗
PubMed1987

Prolonged electrocardiographic monitoring in patients with syncope. Importance of frequent or repetitive ventricular ectopy.

The purposes of this study were to document the findings on prolonged electrocardiographic monitoring in patients with syncope, correlate these findings with symptoms during monitoring, and define the prognostic importance of these findings. A total of 235 patients with syncope in whom a cause was not assigned or suggested by the initial history, physical examination, and electrocardiography were studied. Although a variety of arrhythmias were documented during monitoring, the vast majority of arrhythmias were of short duration and did not produce symptoms. At two years, the patients with frequent or paired premature ventricular contractions (PVCs) when compared with patients with rare PVCs, had a higher incidence of sudden death (18.2 percent versus 4.0 percent; p less than 0.001) and higher overall mortality (28.3 percent versus 10.8 percent; p less than 0.003). Similarly, patients with ventricular tachycardia, when compared with patients with rare PVCs, had a higher incidence of sudden death (18.7 percent versus 4.0 percent; p less than 0.0001) and higher overall mortality (36.5 percent versus 10.8 percent; p less than 0.00001). Cox regression analyses revealed that frequent or repetitive PVCs and sinus pauses were independent electrocardiographic predictors of sudden death and mortality in patients presenting with syncope. Therefore, patients with syncope and frequent or repetitive ventricular ectopy or sinus pauses constitute a high-risk subgroup and may be candidates for more extensive diagnostic evaluation.

Adolescent↗
PubMed1986

Consumer acceptance of prepaid and fee-for-service medical care: results from a randomized controlled trial.

Do consumers find the care provided by health maintenance organizations (HMOs) and that provided in the fee-for-service (FFS) system equally acceptable? To address this question, we randomly assigned 1,537 people ages 17 to 61 either to FFS insurance plans that allowed choice of physicians or to a well-established HMO. We also studied 486 people who had already selected the HMO (control group). Those who had chosen the HMO were as satisfied overall with medical care providers and services as their FFS counterparts. The typical person assigned to the HMO, however, was significantly less satisfied overall relative to FFS participants. Attitudes toward specific features of care favored both FFS and HMO, depending on the feature rated. Four differences (length of appointment waits, parking arrangements, availability of hospitals, and continuity of care) favored FFS; two (length of office waits, costs of care) favored the HMO. HMO versus FFS differences in ratings of access to care and availability of resources mirror differences in the organizational features of these two systems that are generally considered responsible for the significantly lower medical expenditures at HMOs. Regardless of their origin, less favorable attitudes toward interpersonal and technical quality of care in the HMO have marked consequences: dissatisfaction and disenrollment.

Adolescent↗
PubMed1985

Micturition syncope. A reappraisal.

We prospectively studied 33 patients with micturition syncope. Of these, eight were young (mean age, 25 years), healthy individuals whose diagnostic evaluation gave normal findings. The remaining 25 patients were older (mean age, 60 years), and 16 were women. This group had an average of 3.8 acute and chronic illnesses per patient, and was taking 3.5 medications per patient. Physical examination disclosed orthostatic hypotension in 22 of these 25 patients. Therapy was directed at improving orthostasis. Over a mean of 15.3 months, no recurrent micturition syncope or sudden death occurred in the entire group. We conclude that there are two groups of patients with micturition syncope. A group consisting of young healthy men has been well described previously. Our larger group, however, consisted of older patients, more often women with multiple illnesses and the majority having orthostatic hypotension.

Adolescent↗
PubMed1983

A prospective evaluation and follow-up of patients with syncope.

We prospectively evaluated and followed 204 patients with syncope to determine how often a cause of syncope could be established and to define the prognosis of such patients. A cardiovascular cause was established in 53 patients and a noncardiovascular cause in 54. The cause remained unknown in 97 patients. At 12 months, the overall mortality was 14 +/- 2.5 per cent. The mortality rate (30 +/- 6.7 per cent) in patients with a cardiovascular cause of syncope was significantly higher than the rate (12 +/- 4.4 per cent) in patients with a noncardiovascular cause (P = 0.02) and the rate (6.4 +/- 2.8 per cent) in patients with syncope of unknown origin (P less than 0.0001). The incidence of sudden death was 24 +/- 6.6 per cent in patients with a cardiovascular cause, as compared with 4 +/- 2.7 per cent in patients with a noncardiovascular cause (P = 0.005) and 3 +/- 1.8 per cent in patients with syncope of unknown origin (P = 0.0002). Patients with syncope can be separated into diagnostic categories that have prognostic importance. Patients with a cardiovascular cause have a strikingly higher incidence of sudden death than patients with a noncardiovascular or unknown cause.

Adolescent↗
PubMed1977

A signal-processing system for real-time ultrasonic measurement of urine flow parameters.

An application of a signal-processing system to the urethra is described which allows for real-time measurement of the average velocity of the urine at a particular location along the urethra during voiding through measurement of the average frequency in ultrasonic return from scatterers in the flowing urine. In addition, this comparatively simple system provides, without additional instrumentation, the relative urethral cross-sectional area at this location and the relative urine flow rate as functions of time throughout the voiding period. Tests indicate its potential as a valuable transcutaneous diagnostic aid in the detection, study, and treatment of various disorders and diseases of the lower urinary system. The key element of the system is a circuit having a voltage transfer function magnitude proportional to the square root frequency.

Humans↗