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Biomedical subjects

N P Cohen

Publications and source records attributed to N P Cohen.

15 recordsLinked to original sources
PubMed2001

A prospective study to evaluate the role of complexed prostate specific antigen and free/total prostate specific antigen ratio for the diagnosis of prostate cancer.

PURPOSE: Patients are increasingly undergoing prostatic biopsy to identify localized prostate cancer. The decision to perform a biopsy is often made on the basis of total prostate specific antigen (PSA). However, this value lacks adequate specificity for this task. We evaluate the role that a number of these tests, including the Bayer complexed PSA (Bayer Diagnostics, Tarrytown, New York) and free/total PSA ratio, may have in our clinical practice. MATERIALS AND METHODS: A total of 160 consecutive patients attending a prostate assessment clinic were enrolled during an 18-month period in our study. All patients had a previously recorded total PSA (range 2.6 to 20.0 ng./ml.). Before transrectal ultrasound biopsy of the prostate gland, a blood sample was taken with patient consent. The findings on ultrasound were then recorded, including prostate volume. Serum samples were immediately sent for subsequent storage and analysis. RESULTS: Of the patients enrolled 109 had benign histology while 51 had prostatic carcinoma. The 2 patient groups were well matched for age. In our series patients with prostate cancer had significantly smaller prostates and higher mean total PSA. At a high sensitivity, such as 95%, it appeared that Bayer complexed PSA performed better than the other tests and ratios, with an estimated specificity of 24.8% compared with 17.4% for Bayer total PSA and 15.6% for Abbott free/total PSA (Abbott Laboratories, Abbott Park, Illinois). Receiver operator characteristics curves were drawn, and when the areas under them were calculated, we demonstrated that the area under the curve for Bayer complexed PSA (0.706) was between the values for total PSA (0.671) and free/total PSA ratio (0.731). However, the only statistically significant improvement in performance was in Bayer complexed PSA over the total PSA assays. CONCLUSIONS: Our study revealed that the overall diagnostic performance of Bayer complexed PSA appears to be better than the other PSA tests and ratios studied. The use of Bayer complexed PSA may lead to a reduction in the number of men undergoing unnecessary prostatic biopsy.

Aged↗
PubMed2001

Vertebral sarcoidosis of the spine in a football player.

Osseous involvement is common in sarcoidosis, but most cases of osseous sarcoidosis occur in the long bones of the hands and feet. Vertebral involvement in sarcoidosis is rare. A case of vertebral sarcoidosis in a 19-year-old male football player is presented. The patient had clinical, radiologic, laboratory, and pathologic findings consistent with a case of vertebral sarcoidosis. A review of the literature on sarcoid involvement of the spine is also presented. Although rare, sarcoid infiltration of the vertebrae is a recognized entity. Magnetic resonance imaging can be helpful in making the diagnosis, but biopsy is needed for confirmation.

Adult↗
PubMed1998

Composition and dynamics of articular cartilage: structure, function, and maintaining healthy state.

Disorders of articular cartilage represent some of the most common and debilitating diseases encountered in orthopaedic practice. Understanding the normal functioning of articular cartilage is a prerequisite to understanding its pathologic processes. The mechanical properties of articular cartilage arise from the complex structure and interactions of its biochemical constituents: mostly water, electrolytes, and a solid matrix composed primarily of collagen and proteoglycan. The viscoelastic properties of cartilage, due primarily to fluid flow through the solid matrix, can explain much of the deformational responses observed under many loading conditions. Degenerative processes can often be explained by a breakdown of the normal load-bearing capacity of cartilage which arises from the mechanics of this fluid flow. Several factors which may lead to such a breakdown include direct trauma to the cartilage, obesity, immobilization, and excessive repetitive loading of the cartilage. Sports activity, without traumatic injury, does not appear to be a risk factor for the development of osteoarthritis in the normal joint; however, such activity may be harmful to an abnormal joint.

Animals↗
PubMed1994

Does lithotripsy cause hearing loss?

OBJECTIVE: To determine whether lithotripsy with the Dornier MPL9000 has any significant effect on the hearing of either patients or operators, as determined by pure tone audiometry. PATIENTS AND METHODS: Twenty patients had audiometry prior to a single exposure to lithotripsy and one hour after treatment. Staff were monitored on a 3 monthly basis. RESULTS: No evidence was found to suggest that single or repeated exposure to the noise emitted by this Dornier lithotripter was associated with any hearing loss. CONCLUSIONS: These results suggest that the risk to the hearing of patients exposed to lithotripter noise is negligible. Cochlear damage resulting from excessive noise depends on both the intensity of the sound and the duration of exposure. The acoustic properties of the building housing the machine may also be important and can significantly influence the intensity of the sound at the ear. At marginal levels it may be years before the deficit reaches a level that can be detected by subjective audiometry. In addition, susceptibility to noise induced hearing loss is difficult to predict. Although these results suggest that there is minimal risk to the hearing of staff members exposed to lithotripter noise, the authors recommend that staff exposed to repeated lithotripter noise over long periods undergo regular audiometric assessment (including a preemployment baseline assessment) to identify evidence of noise induced auditory trauma, and that protective equipment be worn by staff members to reduce the possibility of long-term damage.

Audiometry↗
PubMed1994

Choosing the correct pain relief for extracorporeal lithotripsy.

OBJECTIVES: To determine the best choice of analgesic for patients undergoing lithotripsy, and to attempt to identify factors which might predict which patients are most likely to find the procedure painful. PATIENTS AND METHODS: Sixty patients with stones in the pelvicalyceal system of the kidney were randomized prospectively to undergo lithotripsy with the Dornier MPL9000 lithotripter (Dormier Medical Systems, Marietta, GA, USA) after receiving either diclofenac 100 mg per rectum (n = 30) or pethidine 50 mg intravenously (n = 30) for analgesia. The patients completed a detailed questionnaire prior to treatment, and the level of pain perceived during lithotripsy was monitored using visual analogue scales (VASs). Arterial oxygen saturation (SaO2) was monitored before analgesia was given, throughout the treatment and for 30 min after cessation of treatment. RESULTS: The VASs were available for 56 patients and the results of pulse oximetry for 51 patients. Although a higher kilovoltage was recorded in the group who received pethidine this difference was not significant. Patients who received diclofenac or pethidine alone, showed a non-significant fall of SaO2 30 minutes after the end of treatment, although the largest fall in SaO2 observed with pethidine was 10%. Patients who received diclofenac and pethidine similarly showed a non-significant fall in SaO2. Four patients received intravenous benzodiazepines in addition to pethidine, and in this group there was a dramatic fall in SaO2 which persisted more than 30 min after the end of treatment (P < 0.0027). Diclofenac provided effective analgesia for most of the patients who underwent lithotripsy. Overall 11 patients (18%) required additional analgesia. Diclofenac or pethidine alone, in the doses used in this study, did not cause a significant drop in SaO2 during ESWL. The only response found to be of value in predicting a painful experience was fear of the dentist. CONCLUSIONS: This study shows that modern lithotripsy, in addition to being safe and effective, can be performed as an out-patient procedure using simple non-opiate analgesics. The need for stronger analgesia and/or sedation should be tailored to the needs of the individual patient, although it remains difficult to predict which patients will require such measures.

Adult↗
PubMed1993

Mechanical testing of urinary calculi.

The ability to predict how easily a stone will break in response to extracorporeal and intracorporeal lithotripsy would be advantageous for the urologist. In a study of fragments from 52 urinary calculi, in vitro microhardness results were found to increase for the series struvite to brushite. Ultrasound velocity measurements performed on 35 intact urinary stones showed a similar trend. This suggests that ultrasound velocity may be a useful indicator of stone strength and one which could be used in vitro to assist the planning of stone treatment.

Elasticity↗
PubMed1993

Choosing a powerful lithotriptor.

Clinicians have no yardstick to help them choose the most efficient lithotriptor. Their leading priority is a system allowing complete disintegration of the stone with the minimum number of shocks and a low re-treatment rate. One of the prerequisites of this system is a powerful shock wave generator. "Power" is as yet ill defined in lithotripsy. Therefore clinicians' choice depends upon other factors. Acoustic output measurements were recorded on 3 commercial lithotriptors representing the 3 main shock wave generating systems. These were the Dornier MPL 9000 (standard and X-155 electrodes), the Siemens (Lithostar, Lithostar Plus and System C) and the Wolf Piezolith 2300. The shock wave measurements were correlated to the capability of the lithotriptors to disintegrate standard stone models in vitro. Two factors were identified. The pulse intensity integral in the focus and the size of the focal zone proved to be the most important factors to assess and compare the efficacy or "power" of different lithotriptors. Together they can help clinicians to identify and choose the most efficient shock wave generating systems.

Acoustics↗
PubMed1992

Prediction of response to lithotripsy--the use of scanning electron microscopy and X-ray energy dispersive spectroscopy.

A single urine sample was obtained from each of 38 patients before and immediately after treatment with a Wolf Piezolith 2300. Each sample was analysed for crystals using scanning electron microscopy and X-ray energy dispersive spectroscopy. In all cases it was possible to make a stone diagnosis prior to treatment and there was 100% correlation between the pre- and post-treatment diagnosis. All stones smaller than 90 mm2 on plain X-ray cleared with piezoelectric lithotripsy alone, regardless of composition. Larger stones composed of calcium oxalate were all successfully fragmented, but 5 of 15 mixed or phosphate stones failed to respond.

Adolescent↗
PubMed1991

Long term complication of untreated bilateral testicular torsion in the newborn. Case report.

Acute bilateral scrotal swelling of the neonate may be caused by a variety of conditions. Bilateral torsion of the testes is an uncommon but important cause of such swelling and must be suspected in all cases. A case of delayed complication of untreated bilateral testicular torsion in the newborn presenting in adolescence is reported and followed by discussion of the literature review.

Adolescent↗
PubMed1988

Successful management of idiopathic intestinal pseudo-obstruction with cisapride.

This is a case report of a previously asymptomatic 11-year-old boy who developed chronic intestinal pseudo-obstruction. Barium studies revealed grossly disordered motility of the proximal small bowel, and ganglion cells in a gastric biopsy were mildly abnormal. Treatment with conventional prokinetic agents and gastrojejunostomy were ineffective. Intravenous cisapride induced an immediate remission, which has been maintained subsequently by rectal administration of the drug.

Administration, Rectal↗
PubMedDate not supplied

Indwelling interscalene catheter anesthesia in the surgical management of stiff shoulder: a report of 100 consecutive cases.

One hundred consecutive stiff shoulders in 93 patients resistant to conservative therapy were treated with surgery and intermittent regional anesthesia via indwelling interscalene catheter. Each patient underwent manipulation and one of several operative treatments to release any additional contracture. The indwelling interscalene catheter remained in place and functioned well for an average of 3 days in 87 shoulders. At an average follow-up of 3.0 years, overall clinical results according to Neer's criteria were excellent in 39 shoulders (39%), satisfactory in 28 (28%), and unsatisfactory in 33 (33%). Patients reported no or mild pain in 83 (83%) of the shoulders in the study. At final follow-up, average gains in motion were 44 degrees of elevation (115 degrees to 159 degrees), 31 degrees of external rotation (22 degrees to 53 degrees), and 5 spine segments of internal rotation (L4 to T11). At final follow-up, 95% of the elevation and 79% of the external rotation achieved intraoperatively were maintained. The best results were obtained in those shoulders with idiopathic stiffness (88% excellent or satisfactory results); the worst results were in the postsurgical shoulders (47% excellent or satisfactory results). There were no catheter-related complications. The use of an indwelling interscalene catheter for postoperative pain control is a safe technique that facilitates early physical therapy in a patient population with a high risk of developing recurrent stiffness.

Adult↗
PubMedDate not supplied

Effects of repetitive subfailure strains on the mechanical behavior of the inferior glenohumeral ligament.

The mechanical response of the inferior glenohumeral ligament to varying subfailure cyclic strains was studied in 33 fresh frozen human cadaver shoulders. The specimens were tested as bone-ligament-bone preparations representing the 3 regions of the inferior glenohumeral ligament (superior band and anterior and posterior axillary pouches) through use of uniaxial tensile cycles. After mechanical preconditioning, each specimen was subjected to 7 test segments, consisting of a baseline strain level L1 (400 cycles) alternating with either 1 (group A, 10 shoulders), 10 (group B, 13 shoulders), or 100 (group C, 10 shoulders) cycles at increasing levels (L2, L3, L4) of subfailure strain. Cycling to higher levels of subfailure strain (L2, L3, L4) produced dramatic declines in the peak load response of the inferior glenohumeral ligament for all specimens. The group of ligaments subjected to 100 cycles of higher subfailure strains demonstrated a significantly greater decrease in load response than the other 2 groups. Ligament elongation occurred with cyclic testing at subfailure strains for all 3 groups, averaging 4.6% +/- 2.0% for group A, 6.5% +/- 2.6% for group B, and 7.1% +/- 3.2% for group C. Recovery of length after an additional time of nearly 1 hour was minimal. The results from this study demonstrate that repetitive loading of the inferior glenohumeral ligament induces laxity in the ligament, as manifested in the peak load response and measured elongations. The mechanical response of the ligament is affected by both the magnitude of the cyclic strain and the frequency of loading at the higher strain levels. The residual length increase was observed in all of the specimens and appeared to be largely unrecoverable. This length increase may result from accumulated microdamage within the ligament substance, caused by the repetitively applied subfailure strains. The clinical relevance of the study is that this mechanism may contribute to the development of acquired glenohumeral instability, which is commonly seen in the shoulders of young athletes who participate in repetitive overhead sports activities.

Adult↗