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Biomedical subjects

G Katz

Publications and source records attributed to G Katz.

At least 73 records · Page 4Linked to original sources
PubMed1992

Extracorporeal shock-wave lithotripsy (ESWL) monotherapy for stones in lower ureter.

Extracorporeal shock-wave lithotripsy (ESWL) has been accepted as the method of choice for most upper urinary tract calculi. However, in cases of stones in the lower ureter, ureteroscopic procedures have generally been preferred. Using the Dornier HM3 lithotriptor with modifications in the patient's position, we were able to successfully treat 155 unselected cases of lower ureteral calculi. The average stone size was 9.6 mm (range 5-23 mm). One hundred forty-three patients had stones located below the lower margin of the sacroiliac joint. These patients were placed in a supine position. The stones were visualized radiologically without use of a ureteral catheter in 78 percent of the patients; in 22 percent a ureteral catheter was inserted prior to ESWL to aid in stone localization. In 145 patients (94%) treatment was completed in one session; 10 patients (6%) required two sessions. Of the patients, 38 percent were free of stones one day after ESWL; 97 percent became stone free within three months, and only 3 patients required endoscopic manipulation, after ESWL. Twelve patients had stones in the midureter overlying the sacroileum. They were placed in the prone position, and the calculi were visualized with the aid of a ureteral catheter. All these patients became free of stones one month after treatment. There were no significant treatment-related complications except for bacteremia in 1 case. In view of the remarkable efficacy, negligible complication rate, and shorter hospital stay as compared to ureteroscopic stone manipulations, we recommend high energy ESWL as the primary monotherapy of mid and lower ureteral stones.

Adolescent↗
PubMed1992

Transfer of psychiatric inpatients: the family perspective.

Data from semistructured interviews with families of psychiatric inpatients revealed both satisfaction and dissatisfaction with hospital psychiatry professionals' practices in the course of patient transfer between units. The most significant issues were involvement of families in planning the transfer, provision of timely and adequate information to families, and availability and support of the staff. Recommendations are made for easing family stress and increasing family cooperation about the transfers.

Adult↗
PubMed1992

Bibliotherapy: the use of books in psychiatric treatment.

The guided use of selected books as an adjunct to treatment is applicable to patients in all stages of life and with a variety of problems. This paper describes the authors' experience using books as an adjunct to therapy with psychiatric patients. The authors define the term, review the literature, and set out the objectives of bibliotherapy. The paper presents some principles to follow when assigning books, and examples of books used for common problems. Finally, examples are given of bibliotherapy in action at two Ontario hospitals, and some future directions are suggested.

Bibliotherapy↗
PubMed1992

Electroconvulsive therapy from a social work perspective.

The purpose of this paper is to fill a gap in the social work literature which has not, to date, included a thorough discussion of electroconvulsive therapy (ECT) from a social work perspective. It discusses the rationale for ECT in current practice; enumerates improvements made in stimulus delivery since convulsive therapy was introduced in 1934; and summarizes the myths, realities, advantages and limitations of the treatment in modern psychiatry. It advocates a team approach, which includes social work support and education of the patient and family regarding treatment related matters and discharge planning. Several clinical vignettes are included to illustrate the types of illness for which ECT is used as well as the social work role with the team and patient/family during hospitalization and discharge planning. The Ontario College of Certified Social Workers Guidelines are used to explain social work interventions. The paper is also relevant to social workers in non-psychiatric settings in understanding and planning with patients and families where a member has experienced ECT.

Bipolar Disorder↗
PubMed1991

[Extracorporeal shock wave lithotripsy for cystine urolithiasis].

We present 31 patients with cystine urolithiasis referred to our extracorporeal shock wave lithotripsy (ESWL) center since 1985. This group differed statistically from the other 3000 patients treated by us for urolithiasis with regard to age, stone burden, number of previous operations, and known duration of urolithiasis. The average known duration in those with cystine stones was 15 years. Of 26 patients with such a history, 22 had an average of 2 operations each. At referral, 14 had bilateral stones and among the others there were 5 nonfunctioning kidneys. Of 26 referred with a diagnosis of cystine nephrolithiasis, only 11 were being treated medically. At presentation, 31 had no stones and 1 was being treated medically. In the other 29 patients, 44 renal-ureteral units had urolithiasis. During follow-up 2 ureteral stones were discharged spontaneously and the other units were treated by ESWL, surgery and/or ureteroscopy, and percutaneous irrigation. 36/42 units were free of significant stone residue, but in 4 there were large gravel remains; 1 kidney was removed primarily and 1 kidney lost its function following prolonged obstruction after ESWL. During follow-up, of 11 patients unable to tolerate D-penicillamine and treated by urinary alkalinization alone, 3 have already formed new stones.

Cystine↗
PubMed1991

Local demineralization as a model for bone strength reductions in lytic transcortical metastatic lesions.

The structural consequences of bone density changes associated with lytic metastatic lesions were investigated using an experimental model of regular, lytic metastatic lesions in bone. Circular holes were drilled in the mid-diaphyseal cortex of paired adult canine femora. The region around the defect was demineralized in one bone of each pair with 0.8 N HCl. Specimens were tested to failure in four-point bending. Defect size was determined from conventional planar radiographs as the maximum apparent defect diameter divided by the periosteal diameter. Demineralization resulted in irregular defect geometries, which increased the maximum defect dimension 33% to 57% with respect to the original drill hole diameter. Demineralization resulted in additional strength reductions beyond those expected from the original drill hole alone. Despite the irregular demineralization patterns observed, strength reductions were in close agreement with those predicted from data for regular, nondemineralized holes (r2 = 0.93). The results demonstrate that irregular diaphyseal defect borders may not require more complex fracture risk predictors than can be determined from analytic and experimental studies of regular defect geometries. Our results also demonstrate that errors of over 100% can occur when measuring diaphyseal defect size from radiographs that are not optimally aligned with respect to the defect.

Animals↗
PubMed1990

Place of extracorporeal shock-wave lithotripsy (ESWL) in management of cystine calculi.

We treated 12 patients with sixteen renal and one ureteral cystine stones primarily with extracorporeal shock-wave lithotripsy (ESWL). Among the stones thirteen were greater than 25 mm. In four stones less than 25 mm, three stones completely disappeared and 1 was reduced to small fragments, following ESWL. In thirteen stones greater than 25 mm, twelve were treated by ESWL initially, and one by surgery. Of the 12 cases treated initially by ESWL, 4 became stone-free, 4 remained with small fragments, and 1 remained with large fragments. Two patients were operated on because of poor response to ESWL and 1 patient lost kidney function because of prolonged obstruction. Disintegration of cystine stones greater than 25 mm required an average of 8,522 shock-waves in 4.33 sessions. The problems associated with application of ESWL monotherapy to cystine stones are presented.

Adolescent↗
PubMed1990

Subacute inhalation toxicity study of an ice-nucleation-active Pseudomonas syringae administered as a respirable aerosol to rats.

The inhalation toxicity of a commercial sample of an ice-nucleation-active Pseudomonas syringae (strain 31a) was evaluated by repetitively exposing rats to about 700 mg/m3 of an aerosol consisting of a suspension of 0.0008, 0.4 or 0.8 g/l of bacteria in water for 2 h per day, 5 days per week for 13-14 exposures. No mortality, moribundity or biologically significant differences in clinical signs, body weight, food consumption or clinical pathology were observed. Animals tested at 500 times (0.4 g/l) and 1000 times (0.8 g/l) the recommended ice-nucleation concentration (0.0008 g/l) exhibited concentration-dependent increased lung weights. Several animals exhibited enlarged tracheobronchial lymph nodes. The pulmonary responses observed are considered compatible with a mild irritant reaction. There was no evidence of bacterial infection. Animals tested at a concentration typical for the discharge mouth of a snow gun (0.0008 g/l) demonstrated no significant biological effect.

Administration, Inhalation↗
PubMed1990

Time dependence of ventricular refractory periods: implications for electrophysiologic protocols.

Cardiac refractory periods are routinely measured during electrophysiologic testing. Informal observations suggested that the effective refractory period lengthened with a prolongation of the time in sinus rhythm (basic cycle length time) between successive runs of drive stimuli (S1S1s). If this were true, failure to control the basic cycle length time could affect the results and interpretation of electrophysiologic testing. To study this phenomenon, the effective refractory period was studied in 20 patients during sinus rhythm and two ventricular paced rates with up to three extrastimuli, while varying the basic cycle length time from 2 to 3, to 10 to 20 s. With each of the stimulation sequences used, the effective refractory period lengthened as the basic cycle length time increased ("basic cycle length time-effective refractory period effect"). The effect was most pronounced when extrastimuli were used during the two ventricular paced rates. As the basic cycle length time increased from 2 to 3 to 20 s, the mean effective refractory period determined during sinus rhythm increased from 296 to 300 ms; with the first ventricular paced rate, the effective refractory period increased from 259 to 272 ms (p less than 0.0003) and with the second ventricular paced rate, the effective refractory period increased from 250 to 263 ms (p less than 0.01). The basic cycle length time-effective refractory period effect became more pronounced as the number of extrastimuli increased. With the second ventricular paced rate, as basic cycle length was increased from 2 to 3 to 20 s, the mean prolongation in the cumulative effective refractory period (S1 to final extrastimulus) as the number of extrastimuli increased from 1 to 2 to 3, was 13 (p less than 0.01), 42 (p less than 0.0003) and 82 ms (p less than 0.001), respectively. Results were confirmed in 17 instances by redetermining the effective refractory period at the 2 to 3 s basic cycle length time after the final 20 s basic cycle length time determination, and demonstrating that it was similar to the effective refractory period after the initial 2 to 3 s basic cycle length time. No further prolongation of the effective refractory period could be demonstrated by increasing basic cycle length time from 20 to 60 s, and no significant effect of medications on the basic cycle length time-effective refractory period effect could be demonstrated.

Adolescent↗
PubMed1989

Characterization of high affinity binding sites for charybdotoxin in sarcolemmal membranes from bovine aortic smooth muscle. Evidence for a direct association with the high conductance calcium-activated potassium channel.

Charybdotoxin (ChTX), a peptidyl inhibitor of the high conductance Ca2+-activated K+ channel (PK,Ca), has been radiolabeled to high specific activity with 125I, and resulting derivatives have been well separated. The monoiodotyrosine adduct blocks PK,Ca in vascular smooth muscle with slightly reduced potency compared with the native peptide under defined experimental conditions. [125I]ChTX, representing this derivative, binds specifically and reversibly to a single class of sites in sarcolemmal membrane vesicles prepared from bovine aortic smooth muscle. These sites display a Kd of 100 pM for the iodinated toxin, as determined by either equilibrium or kinetic binding analyses. Binding site density is about 500 fmol/mg of protein in isolated membranes. The addition of low digitonin concentrations to disrupt the vesicle permeability barrier increases the maximum receptor concentration to 1.5 pmol/mg of protein, correlating with the observations that ChTX binds only at the external pore of PK,Ca and that the membrane preparation is of mixed polarity. Competition studies with ChTX yield a Ki of about 20 pM for native toxin. Binding of [125I]ChTX is modulated by ionic strength as well as by metal ions that are known to interact with PK,Ca. Moreover, tetraethylammonium ion, which blocks PK,Ca with moderately high affinity when applied at the external membrane surface, inhibits [125I]ChTX binding in an apparently competitive fashion with a Ki similar to that found for channel inhibition. In marked contrast, agents that do not inhibit PK,Ca in smooth muscle (e.g. tetrabutylammonium ion, other toxins homologous with ChTX, and pharmacological agents that modulate the activity of dissimilar ion channels) have no effect on [125I]ChTX binding in this tissue. Taken together, these results suggest that the binding sites for ChTX which are present in vascular smooth muscle are directly associated with PK,Ca, thus identifying [125I]ChTX as a useful probe for elucidating the biochemical properties of these channels.

Animals↗
PubMed1989

Fever caused by leaking atherosclerotic abdominal aortic aneurysm.

Two cases of leaking atherosclerotic abdominal aortic aneurysm are presented. The leakage caused fever and leukocytosis, combined with signs of peritoneal irritation. Blood hemoglobin levels were reduced. Both patients were initially treated for sepsis but within hours the cause was identified; both died in the operating theater. The experience of others is reviewed and the mechanism of fever caused by leaking aneurysm is discussed.

Aged↗
PubMed1988

Treatment of complete staghorn calculi by extracorporeal shock wave lithotripsy monotherapy with special reference to internal stenting.

Extracorporeal shock wave lithotripsy monotherapy was used to treat 41 patients with complete staghorn calculi. In 20 patients polyethylene angiographic pigtail catheters were inserted prophylactically as ureteral stents and the other 21 patients did not receive stents. Prophylactic stenting reduced the incidence of complications and the need for percutaneous nephrostomy tubes to relieve subsequent ureteral obstruction. Internal stenting maintained the sterility of the urinary tract and reduced the average hospital stay by a third. Residual stone fragments representing less than 5 per cent of the original stone mass remained in 56 per cent of the patients, particularly in those with hydronephrotic kidneys. We suggest that extracorporeal shock wave lithotripsy monotherapy with prophylactic stenting is the preferred treatment for noninfected complete staghorn calculi.

Adult↗
PubMed1987

Long-term results of surgical repair of coarctation of the aorta--evaluation by exercise test.

Thirty-six patients have been operated on for coarctation of the aorta. The age at operation ranged from 4 to 45 years with a mean of 14 years. Preoperative systolic blood pressure (BP) was above the normal mean + 2 SD in 34 (94%) of the patients. The surgical techniques used for correction of coarctation were: resection and end-to-end anastomosis (50%), resection and graft interposition (25%), patch graft angioplasty (22%) and subclavian artery to descending aorta bypass graft (3%). There was no hospital mortality. Systolic BP measured on hospital discharge available in 30 patients showed an average decrease of 26 mm Hg. The mean follow-up period in 16 of 30 patients (53%) was 7.2 years. All of these patients had a further decrease in systolic BP, and in 14 of 16 (87%) BP was within the mean + 2 SD. Twelve patients were examined in the vascular diagnostic laboratory to determine adequacy of the repair by hemodynamic measures. After average of 7.8 years following operation, all of them had ankle systolic BP higher than brachial systolic pressure; ankle BP did not drop after treadmill walking exercise and the directional Doppler velocity curves from the legs were normal. This study suggested that BP continued to decrease after hospital discharge. We were unable to demonstrate correlation between age at operation and decrease in BP. The adequacy of surgical repair can be assessed by mild effort stress test combined with ankle/arm ratio measurement and directional Doppler velocity curves.

Adolescent↗