Search PubMed⌕ Search

Biomedical subjects

J Weinstein

Publications and source records attributed to J Weinstein.

121 records · Page 7Linked to original sources
PubMedDate not supplied

The role of lumbar spinal elements in flexion.

The forces induced in the disc and ligaments of a lumbar motion segment in resisting a quasi-static external load, using a semi-experimental approach, are presented. The lines of action of ligaments (direction cosines) and disc center for the initial position of the specimen were determined using a morphometer. The changes in these lines of action for a known external load were computed by using the three-dimensional load-deformation characteristics of an intact motion segment. The load-deformation behavior were obtained by applying a known load to the motion segment's superior vertebra and recording the motion produced. A seven dial gauge motion measuring system was used for this purpose. The six equations of equilibrium yielded a statically indeterminate model. A linear optimization technique in conjunction with a cost function enabled the computation of forces in the ligaments as well as forces and moments in the disc. This approach made it possible to determine the component forces without a priori knowledge of the structural properties of ligaments. Typically for an external flexion moment of 6.9 Nm the supraspinous ligament experienced the most force (60 N), followed by capsular ligaments (25 N), and transverse ligaments (15 N). A compressive force of 100 N within the disc was predicted. The load-deformation curve, obtained from this study, for the supraspinous ligament was nonlinear and is in agreement with published experimental results.

Aged↗
PubMedDate not supplied

A comparison of the pupillary and cardiovascular effects of various mydriatic agents in preterm infants.

We conducted a randomized, masked study of pupillary dilating capabilities and associated cardiovascular effects of three solutions. Thirty-four babies less than 1500 grams at birth were studied at six to eight weeks. Group A (n = 10) received phenylephrine (PE) 2.5% and tropicamide 1.0%; Group B (n = 10) PE 2.5%, tropicamide 0.5%, and cyclopentolate 0.5%, Group C (n = 10) PE 1.0% and tropicamide 1.0%; Group D (n = 4) saline 0.9%. One drop was placed in each eye and repeated five minutes later. Pupillary dilation was measured with a metric ruler by direct observation at one hour. Blood pressure (BP) and heart rate (HR) were monitored, using an oscillometer, immediately prior to the instillation of the drops and at five-minute intervals, for 60 minutes. BP and HR increased transiently in all groups receiving mydriatics but returned to baseline values in 25 minutes. This increase was significant in Groups A and B (2.5% PE: p less than 0.02). Group D (saline) showed no change in BP or HR. Postdrop pupillary size was largest in Group A but the differences were not significant. On exposure to bright light, the pupillary size in Group C was significantly smaller than Groups A or B (7.35 +/- 0.59 mm, 7.23 +/- 0.38 mm and 6.75 +/- 0.57 mm in Groups A, B and C, p less than .01). Nevertheless, dilation was sufficient to allow appropriate examination in all infants (pupillary diameter greater than 6.0 mm). Solutions containing 2.5% PE are most effective for use in LBW infants, but produce cardiovascular effects. Solutions containing 1% PE provide adequate dilation with minimum cardiovascular effects.

Cardiovascular System↗
PubMedDate not supplied

Values and prevention.

Explore the source record for details and available documents.

Attitude to Health↗
PubMedDate not supplied

The Delphi methodology (Part one): A useful administrative approach.

The Delphi methodology is used to determine, predict and explore group attitudes, needs and priorities. This paper, the first of a two part series on the Delphi methodology, will provide nurse administrators with the basic information necessary to participate in and conduct projects using the Delphi methodology. The methodology will be defined and issues related to design, sampling, instrumentation and methods of data analysis discussed. The role of the nurse administrator, when the Delphi methodology is used, will then be addressed. In the second paper, administrative applications of the Delphi methodology will be addressed.

Delphi Technique↗
PubMedDate not supplied

The Delphi methodology (Part Two): A useful administrative approach.

The Delphi methodology can provide nurse administrators with relevant and accurate information to facilitate decision making. This paper, the second of a two part series, familiarizes nurse administrators with the application of the Delphi methodology in needs assessments, priority setting, changes in nursing practice, identification of cost containment approaches, development of effectiveness indicators, values clarification, and forecasting. Examples from the health sciences literature and our experiences in administration are presented to outline appropriate approaches for nurse administrators planning similar applications.

Decision Making↗
PubMedDate not supplied

Tolerance of initial diphtheria-tetanus-pertussis immunization in preterm infants.

With the use of neurologic examinations, cranial sonograms, electroencephalograms, an cry analyses, we assessed neurologic function before and after an initial diphtheria-tetanus-pertussis immunization in 22 very low birth weight infants. Mean birth weight was 1036 +/- 137 gm; mean gestational age was 28.0 +/- 1.3 weeks. All 22 infants had recovered from respiratory distress syndrome, 10 infants had been treated for invasive bacterial or fungal infection, and 9 infants had had previous intraventricular hemorrhages. Initial immunization was administered at a mean age of 71 +/- 15 days (range 57 to 120 days) and a mean weight of 1895 +/- 245 gm (1370 to 2280 gm). Clinical reactions were mild and transient. No postimmunization changes in neurologic examinations or objective studies were noted compared with results of preimmunization studies. These findings support the safety of administering an initial diphtheria-tetanus-pertussis immunization to very low birth weight infants at the recommended age of 8 weeks.

Diphtheria-Tetanus-Pertussis Vaccine↗
PubMedDate not supplied

Cystoid macular edema in retinitis pigmentosa.

Cystoid macular edema was commonly observed in retinitis pigmentosa and documented, fluorangiographically, in 70% (41) of 58 consecutive patients. Macular fluorescence representing the intraretinal accumulation of dye from leaking perifoveal capillaries was best seen by simultaneous projection of early- and late-phase angiograms. This facilitated visualization of dim cystoid staining amid mottled and sometimes confusing hyperfluorescence in the posterior pole. Patients of many different ages demonstrated cystoid macular edema and there was no predominant involvement of any particular age group. Although visual acuity was affected in the majority of patients with cystoid macular edema, 25% had 20/25 or better due, perhaps, to sparing of the fovea. Bone corpuscular pigmentation appeared frequently with cystoid macular edema and we were, therefore, unable to corroborate previous opinions that depicted cystoid macular edema as part of a presumed atypical nonpigmented form of retinitis pigmentosa.

Adult↗