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Biomedical subjects

L D Katz

Publications and source records attributed to L D Katz.

At least 19 recordsLinked to original sources
PubMed2001

Superior labral anterior posterior (SLAP) lesions of the glenoid labrum: reliability and accuracy of MR arthrography for diagnosis.

PURPOSE: To determine the reliability and accuracy of magnetic resonance (MR) arthrography for the diagnosis of superior labral anterior posterior (SLAP) tears. MATERIALS AND METHODS: The MR arthrograms in 80 patients who underwent arthroscopy and MR arthrography during a 54-month period were retrospectively reviewed. MR arthrograms were independently scored by three observers for the presence and type of SLAP lesion. Type I SLAP lesions were regarded as negative as they most often are not clinically relevant. Interobserver agreement for detection of SLAP lesions was calculated by using kappa coefficients. The differences in areas under the receiver operating characteristic (ROC) curves were assessed with a univariate z score test. RESULTS: At arthroscopy, there were 25 SLAP tears: type II (n = 22), type III (n = 2), and type IV (n = 1). Sensitivity, specificity, and accuracy of each reader were 92%, 84%, and 86%; 92%, 82%, and 85%; and 84%, 69%, and 74%, respectively. Interobserver agreement for SLAP tears was substantial (kappa = 0.77) to moderate (kappa = 0.52, kappa = 0.44). The areas under the ROC curves for each reader were 0.94, 0.93, and 0.83, which were not significantly different. CONCLUSION: MR arthrography of the shoulder is reliable and accurate for detection of SLAP tears.

Adolescent↗
PubMed2000

Patient perception of magnetic resonance arthrography.

OBJECTIVE: Magnetic resonance (MR) arthrography has been demonstrated to be more accurate than MR imaging alone in the identification of a variety of musculoskeletal pathology. While the complication rate of intra-articular gadolinium: saline injection has been shown to be relatively low, MR arthrography is more invasive, painful, and costly, and less convenient, than MR imaging alone. The purpose of this study was to evaluate patients' perception of the fear and discomfort, and to assess their overall acceptance of the intra-articular gadolinium injection. DESIGN AND PATIENTS: Between October 1997 and January 1998, 113 outpatients who were referred to Yale-New Haven Hospital for MR arthrography of the ankle, elbow, hip, knee, shoulder, or wrist were asked to complete a questionnaire rating their fear of factors most commonly associated with the procedure including "pain", "needles", "complications", and "discovery of results that would lead to surgery". In addition, after having undergone the intra-articular gadolinium:saline injection, patients were asked to rate their perception of pain. RESULTS: While many patients expressed fear of "pain" and "needles", after having undergone the injection their overall pain rating score was low. Only 6% actually found gadolinium arthrography more painful than expected. CONCLUSION: Despite the fact that patients expressed apprehension about certain aspects of MR arthrography, subjects who underwent the intra-articular gadolinium injection considered the discomfort less than expected. Clinicians should not hesitate to order MR arthrography because the accuracy of the procedure is high enough that patients accept the discomfort.

Adolescent↗
PubMed1999

Excess abdominal adiposity remains correlated with altered lipid concentrations in healthy older women.

OBJECTIVE: To determine associations between overall adiposity, absolute and relative abdominal adiposity, and lipid concentrations in healthy older women. DESIGN: Cross-sectional analysis of baseline data. SUBJECTS: Subjects were 21 healthy, untrained older women (71 +/- 1 y) entering a randomized, controlled aerobic training program. MEASUREMENTS: Overall adiposity was assessed by anthropometry and the body mass index (BMI=kg/m2). Absolute and relative abdominal adiposity was determined by computed tomography (CT) and circumference measures. Fasting serum lipid concentrations of total-, high density lipoprotein (HDL)-, and low density lipoprotein (LDL)-cholesterol (C) and triglycerides (TGs) were determined by standard enzymatic procedures. RESULTS: Compared to the measures of overall adiposity, we observed much stronger correlations between measures more specific to absolute or relative abdominal adiposity and lipid concentrations. Visceral fat area was the strongest correlate of HDL-C (r = -0.75; P < 0.001) and the total-/HDL-C ratio (r = 0.86; P < 0.001). The abdomen-to-hip circumference ratio (AHR) was strongly correlated with TGs (r = 0.54; P < 0.01), HDL-C (r= -0.69; P < 0.001), and the total-/HDL-C ratio (r = 0.75; P < 0.001). CONCLUSION: Excess abdominal adiposity remains an important correlate of lipid metabolism, even in healthy older women of normal weight. Thus, overall obesity is not a necessary condition for the correlation between excess abdominal fat and metabolic risk among postmenopausal women.

Abdomen↗
PubMed1999

Augmentation of distal radius fracture fixation with coralline hydroxyapatite bone graft substitute.

We implanted coralline hydroxyapatite bone graft as a substitute for autogenous bone graft to support the reduced articular surface of 21 consecutive patients with distal radius fractures treated with external fixation and K-wires. The purpose of this single-cohort retrospective study was to report the outcomes of treatment with this material, complications associated with its use, and its efficacy in supporting the articular surface reduction. Eighteen patients were available for independent evaluation of motion, subjective outcome analysis, and final radiographic analysis at an average of 35 months after surgery. Wrist motion averaged 90% of the uninjured wrist and grip strength measured 75% of the uninjured side. Results in 17 of the 18 cases were rated as good or excellent by the criteria of Gartland and Werley; 12 by the criteria of Green and O'Brien. Seventeen had good or excellent radiographic results by the modified Lidstrom radiographic scoring system. The average DASH functional/symptom score was 90.3 (maximum, 100). Radiographic parameters were restored to an average of 12 mm radial length, 4 degrees volar tilt, 23 degrees radial inclination, and 0.6 mm positive ulnar variance. Articular reduction was maintained in all patients. A complication related to the use of coral was a 0.5 mm prominence of coralline hydroxyapatite beyond the subchondral line at the radiocarpal joint in 1 patient, which was not present on final radiographs. Coralline hydroxyapatite was effective at maintaining articular surface reduction when used in combination with external fixation and K-wires and had a safety profile comparable to other forms of treatment.

Bone Substitutes↗
PubMed1998

MR arthrography of the hip.

Hip arthroscopy can be performed on an outpatient basis and has a shorter period of rehabilitation than is necessary after an open hip arthrotomy or reconstruction. The procedure makes possible accurate diagnosis and treatment of acetabular labral tears and loose bodies. Further advancements are necessary in optical equipment; manual and motorized equipment; and simple, reliable traction devices specific for this procedure. Refinements in patient selection and the increased availability of specific outcome data will help to define the role of hip arthroscopy in orthopedic practice.

Acetabulum↗
PubMed1998

Moderate-intensity aerobic training improves glucose tolerance in aging independent of abdominal adiposity.

OBJECTIVE: To test the hypothesis that training-related improvements in glucose and insulin responses to an oral glucose tolerance test (OGTT) are independent of changes in abdominal adiposity. DESIGN: Adiposity and responses to an OGTT were measured before and after a 4-month randomized, controlled aerobic training program. SETTING: An academic medical institution. PARTICIPANTS: Sixteen healthy older (73+/-1 year) men and women. INTERVENTION: Both the training (T) (n=9) and control (C) (n=7) groups exercised 4 times a week for 60-minute sessions. T exercised on mini-trampolines at 55 to 65% of HRmax (determined from a graded treadmill test) for 1 month and then at 75% for 3 months; C engaged in supervised stretching and yoga. MEASUREMENTS: At baseline and follow-up, we estimated abdominal fat (from computed tomography and anthropometry), plasma glucose, and serum insulin responses to the OGTT and fasting concentrations of free fatty acids (FFA). RESULTS: Aerobic training resulted in a 16% increase in VO2 peak and a 24% decrease in FFA in the T group (P < .05), but training had no effect on abdominal fat. In the T group, the glucose response curve shifted to the left, and the incremental area under the glucose curve decreased by 25% (P < .05). This improvement in glucose response occurred, however, only in those with impaired glucose tolerance at baseline and without any observed change in insulin response. No change in any variables occurred in the C group. CONCLUSIONS: Our data suggest that moderate-intensity aerobic training has a favorable effect on glucose tolerance in older people, independent of changes in abdominal adiposity.

Abdomen↗
PubMed1997

A non-invasive method for studying in vivo carpal kinematics.

Seven uninjured and three injured patients were studied using midsagittal computed tomographic (CT) images at 10 degrees increments from full extension to full flexion. Each injured patient had a confirmed scapholunate ligament tear and normal radiographs. CT bony contours were digitized, and incremental motion determined using a specifically designed automated contour-matching algorithm. We expressed wrist motion as a ratio of lunocapitate (midcarpal) motion, and radiolunate (radiocarpal) motion. In normal wrists, motion occurred equally at the midcarpal and radiocarpal joints. In wrists with scapholunate ligament disruption, lunocapitate motion increased significantly throughout the arc of motion.

Adult↗
PubMed1997

Rotator cuff: evaluation with fast spin-echo versus conventional spin-echo MR imaging.

PURPOSE: To determine if fast spin-echo (SE) magnetic resonance (MR) imaging can provide similar information to that of conventional SE imaging for evaluation of the rotator cuff. MATERIALS AND METHODS: One hundred twenty-six patients underwent MR imaging with conventional SE and non-fat-suppressed fast SE sequences (65 patients) or conventional SE and fat-suppressed fast SE sequences (61 patients). Two radiologists independently graded the rotator cuff with separate and side-by-side assessment of the fast SE and conventional SE images. RESULTS: For detection of full-thickness tears, agreement between non-fat-suppressed fast SE and conventional SE images was 93.8% (kappa = 0.78 [good]) and 95.4% (kappa = 0.82 [very good]) for the two readers, respectively, and agreement between fat-suppressed fast SE and conventional SE images was 98.4% (kappa = 0.96 [very good]) and 91.8% (kappa = 0.73 [good]) for the two readers, respectively. Rotator cuff grading was similar for fast SE and conventional SE: weighted kappa = 0.77 (good) and 0.68 (good) for non-fat-suppressed and weighted kappa = 0.83 (very good) and 0.67 (good) for fat-suppressed fast SE images for the two readers, respectively. CONCLUSION: Fast SE sequences yield similar interpretations as those obtained with a conventional SE sequence for evaluation of the rotator cuff.

Adolescent↗
PubMed1996

Radiographic progression to dorsal intercalated segment instability.

We present a case of an acute hyper-extension wrist injury that progressed from normal carpal alignment to dorsal intercalated segment instability over a short period of time. Disruption of the scapholunate interosseous and radioscapholunate ligaments was proven arthroscopically, while the intercapsular ligaments were demonstrated to be intact. We have shown that lunate malalignment can occur over time, as secondary lunate ligamentous supports attenuate under abnormal carpal kinetics.

Accidental Falls↗
PubMed1995

Intra-articular impaction fractures of the phalanges.

Six patients with acute impacted fractures of the base of the proximal or middle phalanges were treated with open reduction and internal fixation. Two of three patients who presented with chronic injuries also underwent surgical reconstruction. Contiguous 1.5-mm sagittal computed tomographic imaging was performed on each proximal interphalangeal joint fracture; the imaging documented an average impaction of 30% of the articular surface area. Metaphyseal bone grafting was necessary to support the articular surface in three acute and both late patients. Rigid internal fixation, most frequently employing a composite wire tension band technique, allowed immediate postoperative range of motion exercises. At an average follow-up period of 21 months, all six acute patients had restoration of an excellent painless range of motion. There was no loss of articular congruency on final x-ray films. Late or conservative treatment of these injuries was uniformly less successful.

Accidental Falls↗
PubMed1995

Contribution of hepatic glycogenolysis to glucose production in humans in response to a physiological increase in plasma glucagon concentration.

The contribution of net hepatic glycogenolysis to overall glucose production during a physiological increment in the plasma glucagon concentration was measured in six healthy subjects (18-24 years, 68-105 kg) after an overnight fast. Glucagon (approximately 3 ng.kg-1.min-1), somatostatin (0.1 microgram.kg-1.min-1), and insulin (0.9 pmol.kg-1.min-1) were infused for 3 h. Liver glycogen concentration was measured at 15-min intervals during this period using 13C-labeled nuclear magnetic resonance spectroscopy, and liver volume was assessed from magnetic resonance images. The rate of net hepatic glycogenolysis was calculated from the decrease in liver glycogen concentration over time, multiplied by the liver volume. The rate of glucose appearance (Ra) was calculated from [3-3H]glucose turnover data using a two-compartment model of glucose kinetics. Plasma glucagon concentration rose from 136 +/- 18 to 304 +/- 57 ng/l and plasma glucose concentration rose from 5.6 +/- 0.1 to 10.4 +/- 0.9 mmol/l on initiation of the infusions. Mean baseline Ra was 11.8 +/- 0.4 mumol.kg-1.min-1, increased rapidly after the beginning of the infusions, reaching its highest value after 20-40 min, and returned to baseline by 140 min. Liver glycogen concentration decreased almost linearly (from 300 +/- 19 mmol/l liver at baseline to 192 +/- 20 mmol/l liver at t = 124 min) during 2 h after the beginning of the infusions, and the calculated mean rate of net hepatic glycogenolysis was 21.7 +/- 3.6 mumol.kg-1.min-1. Mean Ra during the same time period was 22.8 +/- 2.3 mumol.kg-1.min-1. Thus, net hepatic glycogenolysis accounted for 93 +/- 9% of Ra.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

13C-nuclear magnetic resonance spectroscopy studies of hepatic glucose metabolism in normal subjects and subjects with insulin-dependent diabetes mellitus.

To determine the effect of insulin-dependent diabetes mellitus (IDDM) on rates and pathways of hepatic glycogen synthesis, as well as flux through hepatic pyruvate dehydrogenase, we used 13C-nuclear magnetic resonance spectroscopy to monitor the peak intensity of the C1 resonance of the glucosyl units of hepatic glycogen, in combination with acetaminophen to sample the hepatic UDP-glucose pool and phenylacetate to sample the hepatic glutamine pool, during a hyperglycemic-hyperinsulinemic clamp using [1-13C]-glucose. Five subjects with poorly controlled IDDM and six age-weight-matched control subjects were clamped at a mean plasma glucose concentration of approximately 9 mM and mean plasma insulin concentrations approximately 400 pM for 5 h. Rates of hepatic glycogen synthesis were similar in both groups (approximately 0.43 +/- 0.09 mumol/ml liver min). However, flux through the indirect pathway of glycogen synthesis (3 carbon units-->-->glycogen) was increased by approximately 50% (P < 0.05), whereas the relative contribution of pyruvate oxidation to TCA cycle flux was decreased by approximately 30% (P < 0.05) in the IDDM subjects compared to the control subjects. These studies demonstrate that patients with poorly controlled insulin-dependent diabetes mellitus have augmented hepatic gluconeogenesis and relative decreased rates of hepatic pyruvate oxidation. These abnormalities are not immediately reversed by normalizing intraportal concentrations of glucose, insulin, and glucagon and may contribute to postprandial hyperglycemia.

Acetaminophen↗
PubMed1993

Soft tissue edema in osteoid osteoma.

Four cases of osteoid osteomas are presented. An uncharacteristic magnetic resonance finding of soft tissue edema is reported. This observation should not be misinterpreted as indicating a more aggressive pathologic process and, thereby, exclude osteoid osteoma from the differential.

Adolescent↗
PubMed1993

Human basal ganglia volume asymmetries on magnetic resonance images.

The brains of 19 healthy adults, ages 18-49, were imaged on a GE Signa 1.5 T MR scanner. Basal ganglia were circumscribed on sequential axial proton density-weighted images (TR 1700, TE 20) and submitted for 3-dimensional reconstruction and volumetric analysis at a computer graphics workstation. The 15 right-handed patients (12 men, 3 women) had significantly larger left total basal ganglia volumes, which included larger globus pallidus and lenticular nuclei on the left, but larger caudate nuclei on the right. In contrast, basal ganglia asymmetries were not seen in four left-handers. No sex differences were detected. The basal ganglia appear to belong to an increasing number of CNS structures that display anatomical hemispheric lateralization.

Adult↗
PubMed1993

Direct measurement of change in muscle glycogen concentration after a mixed meal in normal subjects.

Postprandial storage of carbohydrate as glycogen in muscle was quantitated in normal subjects (n = 8) by natural abundance 13C-nuclear magnetic resonance spectroscopy with proton decoupling in a 4.7-tesla magnet. After an overnight fast three basal measurements of gastrocnemius muscle glycogen were made and a mixed meal was given. Muscle glycogen concentration rose from 83.3 +/- 5.2 to a maximum of 100.2 +/- 6.7 mmol/l muscle at 4.9 h (P < 0.01) and fell thereafter to 90.6 +/- 5.9 mmol/l muscle at 7 h postprandially (P < 0.006). The meal brought about an increase in plasma glucose from 5.4 +/- 0.2 to 7.3 +/- 0.4 mmol/l at 30 min but this was followed by a rapid fall to 6.2 +/- 0.4 mmol/l at 75 min. Plasma insulin rose from 62.4 +/- 11.4 to 900 +/- 216 pmol/l at 30 min and declined steadily thereafter. It was calculated from total muscle mass measurements and estimation of carbohydrate absorption rates that at peak muscle glycogen concentrations between 26 and 35% of the absorbed carbohydrate was stored as muscle glycogen. These data quantitate the role of skeletal muscle glycogen synthesis in postprandial carbohydrate storage and demonstrate that this tissue acts as a dynamic buffer to maintain glucose homeostasis during postprandial substrate storage.

Adult↗
PubMed1993

Reduced basal ganglia volumes in Tourette's syndrome using three-dimensional reconstruction techniques from magnetic resonance images.

Using a 1.5-tesla GE Signa MR scanner, we imaged the brains of 14 right-handed Tourette's syndrome (TS) patients (11 men, three women), aged 18 to 49 years, who had minimal lifetime neuroleptic exposure. We also studied an equal number of normal controls individually matched for age, sex, and handedness and group-matched for socioeconomic status. We circumscribed basal ganglia on sequential axial images from spin-echo proton density-weighted acquisitions (TR 1,700, TE 20; slice thickness, 3 mm with 1.5-mm skip) and submitted the images for three-dimensional processing at a computer graphics workstation. Our hypothesis of lenticular nucleus volume reduction in TS was confirmed for the left- but not the right-sided nucleus. Post hoc analyses revealed smaller mean volumes of the caudate, lenticular, and globus pallidus nuclei compared with controls on both the right and left. Further analyses of basal ganglia asymmetry indices suggest that TS basal ganglia do not have the volumetric asymmetry (left greater than right) seen in normal controls. These findings confirm and extend prior phenomenologic, neuropathologic, and neuroradiologic studies that implicate the basal ganglia in the pathogenesis of TS.

Adult↗