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Biomedical subjects

R Katz

Publications and source records attributed to R Katz.

At least 73 records · Page 4Linked to original sources

[Radical retropubic prostatectomy].

Radical prostatectomy may cure most patients in whom the malignant tumor has not invaded through the prostatic capsule. Advances in surgical technique and accumulation of experience have decreased the complication rate significantly. Long-term results of surgical treatment are now better than those of other forms of treatment; hence radical prostatectomy is now recommended for men with life expectancies longer than 10 years. Between 1988 and 1995, 164 men with clinical stages T1 or T2 adenocarcinoma were admitted for radical prostatectomy. Most were not offered a nerve-sparing procedure, so as to allow wider, more complete resection. Those who wanted preservation of sexual function underwent the nerve- preserving procedure. In 6 patients operation was discontinued when metastases to the mac lymph nodes were detected and in 1 when invasion of the pelvic wall was found, 157 underwent radical prostatectomy. Preoperative biopsy revealed a low-grade lesion (Gleason 2-4) in 19.1%, intermediate grade (Gleason 5-6) in 61.8% and high-grade (Gleason 7-9) in 19.1%; however, pathologic grading revealed that only 7.0% had grade 2-4 tumor, 60.5% grade 5-6 and 32.5% grade 7-9. Pathologic staging revealed T2 tumor in 58%, T3 in 38.8% (including microscopic invasion of the capsule or seminal vesicles); microscopic lymph node metastases were found in 3.2%. Tumor invasion through the capsule was found in only 2 of 13 treated with neoadjuvant androgen blockade, compared with 40% in those who did not receive this treatment. There was no operative mortality and only 14.7% has complications. All had urinary incontinence immediately after operation, but regained continence after an average of 4-5 months, 24 were incontinent for more than 12 months, but most of them had only mild stress incontinence. Most patients were impotent after the procedure. There was tumor recurrence, diagnosed by rise in serum PSA, in 26 during an average followup of 26.4 months (range 3-93). Cure rate of prostatic cancer by radical prostatectomy may be increased by improved preoperative staging methods and better patient selection; long term follow up is required for determining cure rate.

Aged↗

A hospital-based twin register of the heritability of DSM-IV unipolar depression.

OBJECTIVES: To estimate the contribution of genes and shared family environment to the liability to DSM-IV major depression and to examine the influence of certain proband characteristics on twin concordance. METHODS: We studied 177 probands with major depressive disorder ascertained via the Maudsley Hospital Twin Register (London, England) and their same-sex co-twins. Diagnostic assessments were carried out blind to zygosity and information on the other member of the twin pair. Probandwise concordances were used to compute correlations in liability, and model fitting was performed using maximum likelihood procedures. RESULTS: The probandwise concordance was 46% in monozygotic (n = 68) and 20% in dizygotic (n = 109) twins, a statistically highly significant difference. There was no evidence of a sex difference in heritability or of shared environmental effects. Depending on the assumed population risks for DSM-IV, major depression estimates of heritability were between 48% and 75%. A duration of longest episode of less than 13 months, multiple episodes, and an endogenous rather than neurotic pattern of symptoms as established by the International Classification of Diseases, Ninth Revision, in the proband were associated with a trend toward a higher monozygotic-dizygotic concordance ratio. Using log-linear analysis, only the association between duration of episodes and monozygotic-dizygotic concordance ratio was significant. CONCLUSIONS: Liability to DSM-IV major depression has a substantial heritable component, and there is no evidence of an effect of shared family environment. Some proband characteristics, especially shorter duration of episodes, may be associated with a larger degree of genetic determination.

Adult↗

CT of submandibular gland sialolithiasis.

We emphasise the importance of high-resolution CT with reconstruction in the demonstration of submandibular gland (SMG) sialolithiasis and its role in monitoring treatment. We studied 76 patients with swollen and tender SMG, some with fever. They underwent conventional radiography, sonography (US) and high-resolution CT with reconstructions. Conventional radiographs demonstrated single stones in 29 patients. Axial CT, before reconstructions, demonstrated single stones in 63 patients and multiple stones in another 5. Following CT reconstructions, multiple stones were demonstrated in 37 patients. On US stones were diagnosed in only 33 patients, and multiple stones in only 1. All 68 patients with stones shown on imaging and 2 without stones underwent surgery, with good clinical results. Total removal of the SMG and its duct was performed in patients with multiple stones, chronic inflammatory changes in the SMG, or a solitary stone in the SMG or deep in the duct. A small incision for removal of a solitary stone in the distal aspect of Wharton's duct was performed in 15 patients, with excellent clinical results. Another 14 patients with multiple salivary gland stones, diagnosed on CT reconstructions, did not improve following this procedure and needed further surgery; clinical improvement occurred following excision of the SMG and Wharton's duct. Histological examination in all of these confirmed the presence of additional stones. Conservative anti-inflammatory treatment was recommended for 6 patients in whom CT reconstructions did not demonstrate stones.

Adult↗

The hormonal response to intravenous 5-hydroxytryptophan in bulimia nervosa.

In recent years evidence has accumulated to implicate a disturbance in serotonin function in the eating disorder bulimia nervosa. This study employs a neuroendocrine technique to assess the effect of intravenous 5-hydroxytryptophan, the immediate precursor to serotonin, on peripheral hormones in bulimia nervosa subjects and controls. Blunted prolactin and growth hormone responses were observed among bulimia nervosa subjects; the possible pathophysiology and implications of the findings are discussed.

5-Hydroxytryptophan↗

The calculation of radial dose from heavy ions: predictions of biological action cross sections.

The track structure model of heavy ion cross sections was developed by Katz and co-workers in the 1960s. In this model the action cross section is evaluated by mapping the dose-response of a detector to gamma rays (modeled from biological target theory) onto the radial dose distribution from delta rays about the path of the ion. This is taken to yield the radial distribution of probability for a "hit" (an interaction leading to an observable end-point). Radial integration of the probability yields the cross section. When different response from ions of different Z having the same stopping power is observed this model may be indicated. Since the 1960s there have been several developments in the computation of the radial dose distribution, in the measurement of these distributions, and in new radiobiological data against which to test the model. The earliest model, by Butts and Katz made use of simplified delta ray distribution functions, of simplified electron range-energy relations, and neglected angular distributions. Nevertheless it made possible the calculation of cross sections for the inactivation of enzymes and viruses, and allowed extension to tracks in nuclear emulsions and other detectors and to biological cells. It set the pattern for models of observable effects in the matter through which the ion passed. Here we outline subsequent calculations of radial dose which make use of improved knowledge of the electron emission spectrum, the electron range-energy relation, the angular distribution, and some considerations of molecular excitation, of particular interest both close to the path of the ion and the outer limits of electron penetration. These are applied to the modeling of action cross sections for the inactivation of several strains of E-coli and B. subtilis spores where extensive measurements in the "thin-down" region have been made with heavy ion beams. Such calculations serve to test the radial dose calculations at the outer limit of electron penetration. We lack data from which to test these calculations in regions close to the path of the ion aside from our earliest work on latent tracks in plastics, though it appears that the criterion then suggested for the threshold of track formation, of a minimal dose at a minimal distance (of about 20 angstroms, in plastics), remains valid.

Bacillus subtilis↗

CT demonstration of intracranial bleeding in term newborns with mild clinical symptoms.

This paper presents symptomatic term newborns with negative ultrasound examination which showed intracranial bleeding demonstrated by CT scan. Fifty-eight term newborns with Apgars of 9-10 were referred for repeat CT examination of the brain with symptoms, such as apnea, disturbances of swallowing or sucking, impaired muscular tonus, tremor and jerks. The ultrasound examination in all was normal. The first CT scan was performed 12-13 h after delivery. The second CT scan was performed at least two weeks later. Twenty-three of the patients underwent lumbar puncture. Physical examination was performed on each patient--at birth and one week later. The clinical symptoms were still present at the time of the second physical examination. Fourteen to seventeen months following the delivery, the psychomotor development was evaluated in 29 of the children using the Gesell test. In five children, the diagnosis of psychomotor retardation was established which correlated with the brain atrophy demonstrated on CT. Twenty-three newborns who underwent lumbar puncture showed evidence of bleeding into the subarachnoid space. The blood haemoglobin levels of all the cases was below 18 g/dl. The first CT examination demonstrated blood in the subarachnoid space. The second CT scan did not demonstrate any findings. Intracranial bleeding in newborns may be associated with normal delivery. The demonstration of high densities in the first CT scan, the normal second CT scan, the blood tinged or xantochromic CSF and the normal blood haemoglobin levels are indicative of intracranial bleeding.

Cerebral Hemorrhage↗

Effects of track structure and cell inactivation on the calculation of heavy ion mutation rates in mammalian cells.

It has long been suggested that inactivation severely effects the probability of mutation by heavy ions in mammalian cells. Heavy ions have observed cross sections of inactivation that approach and sometimes exceed the geometric size of the cell nucleus in mammalian cells. In the track structure model of Katz the inactivation cross section is found by summing an inactivation probability over all impact parameters from the ion to the sensitive sites within the cell nucleus. The inactivation probability is evaluated using the dose-response of the system to gamma-rays and the radial dose of the ions and may be equal to unity at small impact parameters for some ions. We show how the effects of inactivation may be taken into account in the evaluation of the mutation cross sections from heavy ions in the track structure model through correlation of sites for gene mutation and cell inactivation. The model is fit to available data for HPRT mutations in Chinese hamster cells and good agreement is found. The resulting calculations qualitatively show that mutation cross sections for heavy ions display minima at velocities where inactivation cross sections display maxima. Also, calculations show the high probability of mutation by relativistic heavy ions due to the radial extension of ions track from delta-rays in agreement with the microlesion concept. The effects of inactivation on mutations rates make it very unlikely that a single parameter such as LET or Z*2/beta(2) can be used to specify radiation quality for heavy ion bombardment.

Animals↗

Cutaneous and pulmonary infections caused by Mycobacterium vaccae.

Mycobacterium vaccae is a rapidly growing mycobacterial species that was previously not considered a human pathogen. We report four cases of M. vaccae infection that occurred in the southern United States; one patient had cutaneous disease, and three patients had cavitary lung disease. Two of the three patients with pulmonary disease had a history of exposure to cattle. The conditions of all patients improved with therapy: the cutaneous infection responded to therapy with minocycline and trimethoprim-sulfamethoxazole, and the pulmonary infections responded to therapy with ciprofloxacin.

Aged↗

Branchial pouch sinus tract from the piriform fossa causing acute suppurative thyroiditis, neck abscess, or both: CT appearance and the use of air as a contrast agent.

OBJECTIVE: Our objective was to describe the CT appearance of acute suppurative thyroiditis and neck abscess associated with a congenital sinus tract arising from the piriform fossa. In addition, we describe our observations on the use of air as a contrast agent during CT of the pharynx. CONCLUSION: The thyroid is extremely resistant to acute bacterial infection; hence, when such an infection does occur, an underlying anomaly of the thyroid should be suspected, particularly when the infection is recurrent. In such a case, sonography or CT must be used to confirm the diagnosis of acute thyroiditis, neck abscess, or both. Then the sinus tract must be revealed by barium esophagography, CT scanning that use air as a contrast agent, or endoscopy.

Abscess↗

Detection of hepatocellular carcinoma in cirrhotic patients: sensitivity of CT and ultrasonography.

Patients with cirrhosis are at increased risk for the development of hepatocellular carcinoma. The heterogeneous hepatic parenchyma produced by cirrhosis makes detection of hepatomas more difficult. The purpose of this study was to determine the sensitivities of CT and ultrasonography for detecting hepatomas in cirrhotic patients. A retrospective analysis was performed of 733 patients who underwent liver transplantation at our institution. A study population of 21 patients was selected who met our inclusion criteria. The inclusion criteria required a pathologic diagnosis of hepatocellular carcinoma, pathologic evidence of cirrhosis, and contrast-enhanced CT and sonographic examinations performed within 1 week of each other. The sensitivities of CT and ultrasonography were determined by comparing the imaging findings with pathology findings from serially sectioned total hepatectomy specimens. A total of 40 hepatomas were detected pathologically in the 21 patients in our study population. CT identified 12 of 21 patients with hepatomas and detected 18 of 40 individual lesions (patient detection sensitivity = 57%, lesion detection sensitivity = 45%). Ultrasonography identified 14 of 21 patients with hepatomas and detected 21 of 40 individual lesions (patient detection sensitivity = 67%, lesion detection sensitivity = 51%). Combining the findings of CT and ultrasonography allowed identification of 17 of 21 patients with hepatomas and detection of 24 of 40 individual lesions (patient detection sensitivity = 80%, lesion detection sensitivity = 60%). We conclude that CT and ultrasonography have a low sensitivity for the detection of hepatocellular carcinoma in patients with cirrhosis.

Carcinoma, Hepatocellular↗

Appendiceal colic in children: a true clinical entity?

BACKGROUND: Unexplained recurrent abdominal pain is a frequent problem in the pediatric population. An organic cause is found in 10 percent of children. Recurrent abdominal pain is responsible for multiple hospital admissions and patient evaluations. In some children, partial luminal obstruction of the appendix without inflammation may be the cause of this pain, and is defined as "appendiceal colic." STUDY DESIGN: During a period of five years, we performed a prospective study among children admitted for right lower quadrant abdominal pain. Children operated on for suspected acute appendicitis were eliminated from the study. Among the remaining patients, those with recurrent pain were evaluated for appendiceal colic. Medical histories were obtained, and the patients underwent physical examinations, routine laboratory studies, stool cultures, abdominal roentgenograms, and sonography scans (including the pelvic region in girls). Precise radiologic evaluation of the appendix was performed by barium swallow in 22 children or by barium enema in four. The diagnosis of appendiceal colic was made if the following three criteria were met: a history of longer than one month with three or more recurrent attacks of right lower quadrant abdominal pain; localized tenderness in the right lower abdomen without signs of peritoneal irritation or inflammation; or radiologic findings at barium examination consisting of irregular filling of the appendix, nonfilling or partial filling of the appendix after 24 hours, or nonemptying of the appendix after 72 hours. Children thus diagnosed underwent elective appendectomy, which was performed only after an additional episode of abdominal pain. RESULTS: Twenty-six children (average age 11.4 years) were treated by appendectomy and of these, 23 (88.5 percent) experienced pain relief in the immediate postoperative period. The remaining three children had pain relief within four months after appendectomy. CONCLUSIONS: Appendiceal colic may be a true clinical entity. Children suffering from appendiceal colic may benefit from elective appendectomy.

Adolescent↗

Intraoperative maintenance of tissue perfusion prevents ARDS. Adult Respiratory Distress Syndrome.

Patients undergoing prolonged, complex oncological surgery are at increased risk of developing the adult respiratory distress syndrome (ARDS) and other organ failures. Our hypothesis is that maintaining adequate tissue perfusion and oxygenation may prevent tissue hypoxia and acidosis in pulmonary, peripheral, and splanchnic microcirculations. Experimental evidence suggests that the hypoxic, acidotic endothelium stimulates the release of cytokines, kinins, and other mediators. We developed and tested an intraoperative protocol for surgical patients likely to develop ARDS and organ dysfunction; the protocol focuses on the intraoperative period but is not limited to this time. Nitroglycerin and fluids were used to maintain tissue perfusion and prevent tissue hypoxia as reflected by transcutaneous oxygen tension values. In 155 high-risk patients, none developed ARDS. We conclude that maintenance of tissue perfusion and oxygenation in high-risk surgical patients decreases the incidence of ARDS.

Adult↗

Reciprocal inhibition between wrist flexors and extensors in man: a new set of interneurones?

1. Interneurones mediating reciprocal inhibition between wrist flexors and extensors in man are characterized using both Renshaw cells and transarticular group I afferent activation. 2. Renshaw cells were activated by reflex discharges evoked by a tendon tap. The tendon tap was applied to the tendon of the muscles from which the Ia fibres responsible for the reciprocal inhibition originated. Contrary to what was observed both in the cat hindlimb and in human elbow muscles, this Renshaw cell activation never resulted in a long depression of the reciprocal inhibition between wrist flexors and extensors. 3. Convergence from group I elbow muscle afferents and antagonistic group I afferents onto interneurones mediating reciprocal inhibition between wrist muscles was revealed in post-stimulus time histogram (PSTH) experiments using the technique of spatial facilitation. 4. The characteristics of the interneurones mediating reciprocal inhibition between wrist flexors and extensors could therefore be summarized as follows: (a) they are fed by antagonistic group I afferents and group I afferents originating from both flexor and extensor elbow muscles; (b) they are not inhibited by Renshaw cells; (c) they are not excited by low threshold cutaneous afferents; and (d) they are probably interposed in a disynaptic pathway. 5. It is therefore concluded that interneurones mediating reciprocal inhibition between wrist flexors and extensors in man differ both from Ia interneurones and from interneurones interposed in the Ib reflex pathways and these characteristics are related to the complex circumduction movements developed in the wrist.

Adult↗

Chromosome X numerical abnormalities in patients with non-Hodgkin's lymphoma. A study of 59 patients using fluorescence in situ hybridization.

Chromosome X numerical abnormalities are frequently observed in non-Hodgkin's lymphoma (NHL), with an incidence of 3% to 14% for chromosomal loss and 7% to 33% for chromosomal gain. Because sex chromosome numerical abnormalities are thought to be due to aging, little information is known about their relation to gender, therapy, and prognosis. Therefore, to determine the incidence and clinical relevance of this abnormality in NHL, we studied specimens from 59 NHL patients (31 men and 28 women) by fluorescence in situ hybridization (FISH) using a directly conjugated centromeric probe for chromosome X. The median age for the entire group was 52 years (range, 31-88 years). All specimens were obtained by fine-needle aspiration of diseased lymph nodes. Sex-matched lymphocytes from benign hyperplastic lymph nodes were used as controls. The overall incidence of chromosome X numerical abnormalities was 49.2%. Female patients had a higher overall incidence than males (76% vs. 24%; p < 0.001). The median percentage of cells involved in this abnormality in each specimen was 5.2%. There was no statistically significant difference in the incidence in previously treated than untreated patients (53.1% vs. 44.4%; p < 0.75) and in intermediate-grade NHL than low-grade NHL (61.1% vs. 50%; p < 0.75). There was a trend towards a higher incidence of chromosome X loss in older patients. While the difference in the incidence of chromosome X abnormalities observed between women and men may be due to the difference in the normal copy numbers of this chromosome in each sex group, this abnormality remained higher than any other autosomal chromosome abnormality in NHL previously evaluated by FISH. We conclude that, although FISH detected a high incidence of chromosome X numerical abnormalities and that females had a higher incidence than males, only a small percentage of the cells were involved, suggesting that this abnormality is most likely a secondary genetic defect that is not important in the pathogenesis of NHL.

Adult↗

Definition of the best prediction criteria of the time domain signal-averaged electrocardiogram for serious arrhythmic events in the postinfarction period. The Cardiac Arrhythmia Suppression Trial/Signal-Averaged Electrocardiogram (CAST/SAECG) Substudy Investigators.

OBJECTIVES: The goal of this study was to establish guidelines for the prognostic use of the time domain signal-averaged electrocardiogram (ECG) after myocardial infarction. BACKGROUND: Previous studies of the prognostic use of the signal-averaged ECG in postinfarction patients had one or more of the following limitations: a small study group, empiric definition of an abnormal recording and possible bias in the selection of high risk groups or classification of arrhythmic events, or both. To correct for these limitations, a substudy was conducted in conjunction with the Cardiac Arrhythmia Suppression Trial (CAST). METHODS: Ten centers recruited 1,211 patients with acute myocardial infarction without application of the ejection fraction or Holter criteria restrictions of the main CAST protocol. Several clinical variables, ventricular arrhythmias on the Holter recording, ejection fraction and six signal-averaged ECG variables were analyzed. Patients with bundle branch block were excluded from the analysis, and the remaining 1,158 were followed for up to 1 year after infarction. The classification of arrhythmic events was reviewed independently by the CAST Events Committee. RESULTS: During an average (+/- SD) follow-up of 10.3 +/- 3.2 months, 45 patients had a serious arrhythmic event (nonfatal ventricular tachycardia or sudden cardiac arrhythmic death). A Cox regression analysis with only the six signal-averaged ECG variables indicated that the filtered QRS duration at 40 Hz > or = 120 ms (QRSD-40 Hz) at a cutpoint > or = 120 ms was the most predictive criterion of arrhythmic events. In a regression analysis that included all clinical, Holter and ejection fraction variables, a QRSD-40 Hz > or = 120 ms was the most significant predictor (p < 0.0001). The positive, negative and total predictive accuracy and odds ratio for QRSD-40 Hz > or = 120 ms were 17%, 98%, 88% and 8.4, respectively, and improved to 32%, 97%, 94% and 16.7, respectively, after combination with ejection fraction < or = 40% and complex ventricular arrhythmias on the Holter recording. CONCLUSIONS: The signal-averaged ECG predicts serious arrhythmic events in the first year after infarction better than do clinical, ejection fraction and ventricular arrhythmia variables, and QRSD-40 Hz > or = 120 ms provides the best predictive criterion in this clinical setting.

Arrhythmias, Cardiac↗

Changes in reciprocal and transjoint inhibition induced by muscle fatigue in man.

The effects of localised muscle fatigue on group I reflex pathways were studied in the human upper limb. Activation of group I afferents originating from biceps and extensor carpi radialis (ECR) resulted in an inhibition of flexor carpi radialis (FCR) motoneurones, probably through a disynaptic pathway. Reciprocal inhibition (from ECR to FCR) and transjoint inhibition (from biceps to FCR) were compared before and during localised fatigue induced in the muscle from which group I afferents originated. Fatigue of wrist extensors did not modify the reciprocal inhibition, while during fatigue of elbow flexors the transjoint inhibition was less pronounced. This striking difference between reciprocal and transjoint inhibition is discussed in relation to the pattern of diffusion of voluntary contractions during fatigue in the human upper limb.

Adult↗

Use of a tantalum-178 generator and a multiwire gamma camera to study the effect of the Mueller maneuver on left ventricular performance: comparison to hemodynamics and single photon emission computed tomography perfusion patterns.

During the Mueller maneuver, there is a decrease in intrathoracic pressure and an increase in transmural left ventricular pressure. The changes in loading conditions cause transient left ventricular dysfunction. This study examined the effects of the Mueller maneuver on left ventricular performance using tantalum (Ta)-178 (half-life 9.3 min) and a multiwire gamma camera. First-pass radionuclide angiograms were obtained at baseline and during Mueller maneuver in 41 patients aged 58 +/- 10 years. In 34 patients, stress single photon emission computed tomography (SPECT) myocardial perfusion imaging with thallium-201 or sestamibi was also performed. Hemodynamic measurements during the Mueller maneuver (n = 10) showed a decrease in systemic pressure (139 +/- 25 mm Hg vs 123 +/- 24 mm Hg, p < 0.001) and pulmonary artery pressure (24 +/- 6 mm Hg vs 14 +/- 12 mm Hg, p = 0.01) and an increase in heart rate (67 +/- 10 bpm vs 75 +/- 14 beats/min, p = 0.001). Among the 34 patients who had perfusion imaging, the left ventricular ejection fraction remained unchanged or increased in 17 patients (group 1) (48% +/- 19% vs 49% +/- 21%, p not significant) and decreased (> or = 5%) in 17 patients (group 2) (55% +/- 13% vs 40% +/- 16%, p = 0.001). The stress SPECT images showed no or only fixed defects in 11 (65%) patients in group 1 and 3 (18%) patients in group 2 (p = 0.02), and reversible defects in 6 (35%) patients in group 1 and 14 (82%) patients in group 2 (p = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Exposure with response prevention treatment of anorexia nervosa-bulimic subtype and bulimia nervosa.

Binge exposure with response-prevention of bingeing (ERP-B) was evaluated in 20 female Ss within an inpatient eating disorders unit over 9 sessions as an adjunct to standard milieu therapy. Subjects met DSM-III-R criteria for either bulimia nervosa (BN) (n = 13) or the bulimic subtype of anorexia nervosa (AN-B) (n = 7). The average age of the Ss in each group was 26.5 (+/- 8.8) and 24.1 +/- 6.0) yr, respectively. Results indicate significant within-session and pre-post treatment effects in self-report measures 'urge to binge', 'lack of control', 'feelings of guilt' and 'tension'. Further analysis revealed that the AN-B subgroup had significantly greater reduction in 'depression' and 'urge to vomit' compared to the BN group. This study provides preliminary evidence that ERP-B deserves further investigation with long-term follow-up in both BN and AN-B patients and may be particularly advantageous in the AN-B subpopulation.

Adolescent↗