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Biomedical subjects

A Katz

Publications and source records attributed to A Katz.

At least 37 records · Page 2Linked to original sources
PubMed2001

The influence of pathologic tumor characteristics on locoregional recurrence rates following mastectomy.

PURPOSE: The objective of this study was to evaluate the influence of pathologic factors other than tumor size and number of involved axillary nodes on the risk of locoregional recurrence (LRR) following mastectomy. PATIENTS AND METHODS: We reviewed the medical records of 1031 patients treated with mastectomy and doxorubicin-based chemotherapy without radiation on 5 prospective clinical trials. Median follow-up was 116 months (range, 6-262 months). RESULTS: Patients with gross multicentric disease were at increased risk of LRR (37% at 10 years). However, patients with multifocal disease and those with microscopic multicentric disease did not experience higher rates of LRR than those with single lesions (17% at 10 years). Patients with lymph-vascular space invasion (LVSI) or involvement of the skin or nipple also experienced high rates of LRR (25%, 32%, and 50%, respectively). The presence of close (<5 mm) or positive margins was associated with an increased risk of LRR (45%). The increased risk of LRR observed for patients with pectoral fascial invasion (33%) was not reduced when negative deep margins were obtained. On multivariate analysis, the presence of 4 or more involved axillary nodes, tumor size of greater than 5 cm, close or positive surgical margins, and gross multicentric disease were found to be independent predictors of LRR (all, p < 0.01). In a separate analysis including only patients with 1-3 involved axillary nodes, microscopic invasion of the skin or nipple, pectoral fascial invasion, and the presence of close or positive margins were significant predictors of LRR. CONCLUSION: In addition to the extent of primary and nodal disease, other factors that predict for high rates of LRR include the presence of LVSI, involvement of the skin, nipple or pectoral fascia, close or positive margins, or gross multicentric disease. These factors predict for high LRR rates regardless of the number of involved axillary nodes.

Adult↗
PubMed2001

Recursive partitioning analysis of locoregional recurrence patterns following mastectomy: implications for adjuvant irradiation.

PURPOSE: Postmastectomy irradiation improves overall survival for breast cancer patients at high risk for locoregional recurrence (LRR). The objective of this study was to use recursive partitioning analysis (RPA) to define patient subgroups at high risk for LRR following mastectomy. PATIENTS AND METHODS: A cohort of 1031 patients treated on prospective trials with mastectomy and doxorubicin-based chemotherapy without irradiation was analyzed. The variables considered in the RPA were tumor size, number of involved nodes, number of nodes examined, and percentage of nodes involved (nodes involved/nodes examined). The endpoint was LRR +/- distant metastasis. Only patients with complete data were analyzed (n = 913). Median follow-up was 8 years (range, 0.7-22 years). RESULTS: Involvement of 20% or more of the lymph nodes examined was the most significant variable predicting LRR. Three risk categories were defined. Patients with 20% or more involved nodes and tumors of 3.5 cm or more were at greatest risk for LRR (41% at 8 years). An intermediate-risk group included patients with 20% or more involved nodes and tumors of less than 3.5 cm as well as those with less than 20% involved nodes and tumor size of 5 cm or greater (18% at 8 years). Patients with less than 20% involved nodes and tumor size of less than 5 cm were at lowest risk for LRR (10% at 8 years). CONCLUSION: Tumor size and extent of nodal involvement play interrelated roles in predicting LRR following mastectomy and systemic therapy. Patients with 20% or greater involved nodes and those with less than 20% nodes and tumors of 5.0 cm or greater are at significant risk of LRR and should be considered for postoperative irradiation.

Adult↗
PubMed2001

Role of myoplasmic phosphate in contractile function of skeletal muscle: studies on creatine kinase-deficient mice.

1. Increased myoplasmic inorganic phosphate (P(i)) has been suggested to have an important role in skeletal muscle fatigue, especially in the early phase. In the present study we used intact fast-twitch muscle cells from mice completely deficient in creatine kinase (CK(-/-)) to test this suggestion. These CK(-/-) muscle cells provide a good model since they display a higher P(i) concentration in the unfatigued state and fatigue without significant increase of P(i). 2. Tetanic contractions (350 ms duration) were produced in intact single muscle fibres. The free myoplasmic [Ca(2+)] ([Ca(2+)](i)) was measured with the fluorescent indicator indo-1. The force-[Ca(2+)](i) relationship was constructed from tetani at different frequencies. 3. Compared with wild-type fibres, CK(-/-) fibres displayed lower force in 100 Hz tetani and at saturating [Ca(2+)](i) (i.e. 100 Hz stimulation during caffeine exposure), higher tetanic [Ca(2+)](i) during the first 100 ms of tetanic stimulation, reduced myofibrillar Ca(2+) sensitivity when measurements were performed 100-200 ms into tetani, and slowed force relaxation that was due to altered cross-bridge kinetics rather than delayed Ca(2+) removal from the myoplasm. 4. In wild-type fibres, a series of 10 tetani resulted in reduced tetanic force, slowed force relaxation, and increased amplitude of [Ca(2+)](i) tails after tetani. None of these changes were observed in CK(-/-) fibres. 5. Complementary experiments on isolated fast-twitch extensor digitorum longus muscles showed a reduction of tetanic force and relaxation speed in CK(-/-) muscles similar to those observed in single fibres. 6. In conclusion, increased P(i) concentration can explain changes observed in the early phase of skeletal muscle fatigue. Increased P(i) appears to be involved in both fatigue-induced changes of cross-bridge function and SR Ca(2+) handling.

Animals↗
PubMed2001

Plasma membrane electron transport coupled to Na(+) extrusion in the halotolerant alga Dunaliella.

The halotolerant alga Dunaliella adapts to exceptionally high salinity and maintains low [Na(+)](in) at hypersaline solutions, suggesting that it possesses efficient mechanisms for regulating intracellular Na(+). In this work we examined the possibility that Na(+) export in Dunaliella is linked to a plasma membrane electron transport (redox) system. Na(+) extrusion was induced in Dunaliella cells by elevation of intracellular Na(+) with Na(+)-specific ionophores. Elevation of intracellular Na(+) was found to enhance the reduction of an extracellular electron acceptor ferricyanide (FeCN). The quinone analogs NQNO and dicumarol inhibited FeCN reduction and led to accumulation of Na(+) by inhibition of Na(+) extrusion. These inhibitors also diminished the plasma membrane potential in Dunaliella. Anaerobic conditions elevated, whereas FeCN partially decreased intracellular Na(+) content. Cellular NAD(P)H level decreased upon enhancement of plasma membrane electron transport. These results are consistent with the operation of an electrogenic NAD(P)H-driven redox system coupled to Na(+) extrusion in Dunaliella plasma membrane. We propose that redox-driven Na(+) extrusion and recycling in Dunaliella evolved as means of adaptation to hypersaline environments.

Cell Membrane↗
PubMed2001

Second neoplasms in patients with Merkel cell carcinoma.

BACKGROUND: Merkel cell carcinoma (MCC) has been associated with a high incidence of other skin tumors and hematological malignancies. The purpose of this study was to analyze data from the Israel Cancer Registry regarding the incidence of second neoplasms in patients with MCC and their impact on survival. METHODS: Sixty-seven patients in whom MCC was diagnosed between 1983 and 1999 were included. Data were collected on age, gender and ethnic origin, dates of diagnosis of MCC and any other neoplasm, and date and cause of death, if applicable. Comparison of MCC-specific survival, estimated by the Kaplan-Meier product limit method, between patients with no other neoplasm and those with second primary tumors was performed by log rank test. Age-specific standardized incidence ratio (SIR) was calculated using 5751 age- and ethnic-matched malignant melanoma patients as a control group. RESULTS: Seventeen patients (25%) had a second neoplasm before, concomitant with, or after the diagnosis of MCC; 2 of them also had a third primary tumor. The SIR was 2.8 (95% CI; range, 1.38-4.22), significantly higher than the control group. Almost half the tumors were squamous cell carcinomas, either skin or head and neck, and most of the remainder were hematological malignancies or breast and ovarian adenocarcinomas. On univariate analysis, the presence of another neoplasm, regardless of its chronology, was associated with higher MCC-specific mortality (65% vs. 40% for patients with MCC only; P = 0.022). Analysis of only those patients in whom a second neoplasm developed during follow-up after treatment for MCC yielded an estimated actuarial risk of developing a second primary of 2.1% for each year of observation. CONCLUSIONS: There is a high incidence of second neoplasms, including noncutaneous solid tumors, in patients with MCC. The presence of these neoplasms, whether they appear before, after, or simultaneously with MCC, is associated with a higher MCC-specific mortality.

Adult↗
PubMed2001

[Cancer of the prostate: influence of nutritional factors. General nutritional factors].

OBESITY: Studies attempting to establish an epidemiological link between body mass index and the risk of cancer of the prostate have been contradictory. ENERGY INTAKE: No straightforward relationship between energy intake and cancer of the prostate has been identified. FAR INTAKE: According to epidemiology studies, there is a correlation between high-fat diet and the incidence of cancer of the prostate. It has thus been demonstrated that men whose diet contains more than 30 to 40% fat have a higher risk of developing cancer of the prostate than those whose diet contains less than 30% fat. In addition, high-fat diets favor progression of tumors in elderly subjects. ROLE OF SATURATED FAT: Saturated fat has been implicated most often in the development of cancer of the prostate, high intake being correlated with shorter survival after diagnosis of cancer.

Age Factors↗
PubMed2001

[Cancer of the prostate: influence of nutritional factors. Vitamins, antioxidants and trace elements].

CANCER OF THE PROSTATE AND VITAMINS: Four vitamins have been studied, vitamins A, E, D and C. the results of these studies have been contradictory. Vitamin A and vitamin E would have a protective effect. ANTIOXIDANTS: Carotenes have an activity similar to that of vitamin A. Beta-carotene was positively associated with risk of cancer of the prostate in one study while two others were unable to demonstrate any relationship. Lycopene, the red color in fruits and vegetables, particularly tomatoes, would contribute to a lower risk of prostate cancer. TRACE ELEMENTS: Cadmium would increase the risk of cancer while selenium would have a protective effect. However studies concerning selenium carry certain methodological biases.

Aged↗
PubMed2001

[Cancer of the prostate: influence of nutritional factors. A new nutritional approach].

FIBERS: A group of vegetarian subjects have been shown to have a lower risk of cancer of the prostate than a control group. But the exact role of food fiber remains to be determined because plant foods also have an antioxidant effect on their own. PLANT PRODUCTS AND EXTRACTS: A compound called PD SPEC has been showed to have antitumor effects both in vitro and in vivo. Evaluated in patients with a cancer escaping hormone control, the clinical response was a lower level of prostate specific antigen (PSA). SOYBEANS: Several studies have demonstrated the interesting properties of soybeans. No study has however been able to demonstrate the optimal dose per day. A prospective study is currently under way using a 40 g/day dose. OVERALL NUTRITIONAL APPROACH: Several studies are being conducted using a proposed diet where 15% of the total energy intake comes from fat (associated with a low saturated/unsaturated ratio), high fiber content (18 g/100 kcal) and 40 g daily soybean protein. Although large-scale studies with rigorous methodology are lacking, an overall nutritional approach could be an interesting strategy for the management of cancer of the prostate.

Animals↗
PubMed2001

Removal of chlorine dioxide disinfection by-products by ferrous salts.

Chlorine dioxide when used as an effective disinfectant forms undesirable disinfection by-products, i.e. chlorite and chlorate ions. The aim of this research was to study the removal of these ions by ferrous ions in the presence or absence of oxygen. The efficiency of Fe+2 for ClO2- and ClO3- removal was followed by a determination of their initial and final concentrations, pH and delta Fe+2 consumed/delta ClO2- removed ratios. The optimal weight ratio of delta Fe+2 consumed/delta ClO2- removed for complete ClO2 removal was found to be close to the theoretical calculated value of 3.31. It was proved that ferrous salts can reduce chlorite ions to harmless Cl- ions. This method can be recommended as a part of ClO2 disinfection to ensure safe drinking water, with no harm to water consumers and to the environment.

Chlorates↗
PubMed2001

Cement solidification of simulated off-gas condensates from vitrification of low-level nuclear waste solutions.

Solidification in a cementitious matrix is a viable alternative for low-level nuclear waste management; it is therefore important to understand the behavior and properties of such wasteforms. We have examined the cementitious solidification of simulated off-gas waste streams resulting from the vitrification of low-level nuclear waste. Different possible methods for scrubbing the off-gasses from a vitrifier give rise to three possible types of waste compositions: acidic (from aqueous dissolution of volatile NOx and POx carried over from the vitrifier), basic (from neutralizing the former with sodium hydroxide), and fully carbonated (arising from a direct-combustion vitrifier). Six binder compositions were tested in which ordinary Portland cement was replaced at different proportions by fly ash and/or ground granulated blast furnace slag. A high solution to binder ratio of 1l/1 kg was used to minimize the volume of the wasteform and 10% attapulgite clay was added to all mixes to ensure that the fresh mix did not segregate prior to setting. The 28-day compressive strengths decreased when a high proportion of cement was replaced with fly ash, but were increased significantly when the cement was replaced with slag. The heats of hydration at early age for the various solids compositions decreased when cement was replaced with either fly ash or slag; however, for the fly ash mix the low heat was also associated with a significant decrease in compressive strength. High curing temperature (60 degrees C) or the use of extra-fine slag did not significantly affect the compressive strength. Recommendations for choice of binder formulations and treatment of off-gas condensates are discussed.

Environmental Pollution↗
PubMed2001

The role of Ca2+ and calmodulin in insulin signalling in mammalian skeletal muscle.

The role of Ca2+ in mediating effects of insulin on skeletal muscle has been widely debated. It is believed that in skeletal muscle Ca2+ has a permissive role, necessary but not of prime importance in mediating the stimulatory actions of insulin. In this review, we present evidence that insulin causes a localized increase in the concentration of Ca2+. Specifically, insulin induces a rise in near-membrane Ca2+ but not the bulk Ca2+ in the myoplasm. The rise in near-membrane Ca2+ is because of an influx through channels that can be blocked by L-type Ca2+ channel inhibitors. Calcium appears to exert some of its subsequent effects via calmodulin-dependent processes as calmodulin inhibitors block the translocation of glucose transporters and other enzymes as well as the insulin-stimulated increase in glucose transport.

Animals↗
PubMed2001

Waiting for something to happen: hospitalization with placenta previa.

BACKGROUND: Placenta previa occurs in approximately 1 of every 200 pregnancies. No research examining women's experiences of this condition has been published. The objective of this study was to describe the experience of women hospitalized with placenta previa. METHODS: A descriptive study was conducted using a convenience sample of 10 pregnant women who had been hospitalized with placenta previa. Women were recruited from a tertiary care hospital and participated in two semistructured interviews during the pregnancy and one after the baby's birth while in hospital. They were admitted to hospital from 28 weeks' gestation and remained in hospital until delivery, generally at 36 weeks' gestation. Transcripts of the interviews were analyzed using content analysis to describe their experience. RESULTS: Six themes were identified from the descriptions of the experience as related by the participants. They encompassed the experience from the first symptoms to feelings about the experience after the baby was born. CONCLUSIONS: Women with placenta previa experience significant stressors while in hospital. Health caregivers should be aware of the loss of control and isolation these women feel and be mindful of the potential for sequelae in the postpartum period.

Female↗
PubMed2001

A dysfunctional movement protein of tobacco mosaic virus interferes with targeting of wild-type movement protein to microtubules.

The Tobacco mosaic virus (TMV) movement protein (MPTMV) mediates cell-to-cell viral trafficking by altering properties of the plasmodesmata (Pd) in infected cells. During the infection cycle, MPTMV becomes transiently associated with endomembranes, microfilaments, and microtubules (MT). It has been shown that the cell-to-cell spread of TMV is reduced in plants expressing the dysfunctional MP mutant MPNT-1. To expand our understanding of the MP function, we analyzed events occurring during the intracellular and intercellular targeting of MPTMV and MPNT-1 when expressed as a fusion protein to green fluorescent protein (GFP), either by biolistic bombardment in a viral-free system or from a recombinant virus. The accumulation of MPTMV:GFP, when expressed in a viral-free system, is similar to MPTMV:GFP in TMV-infected tissues. Pd localization and cell-to-cell spread are late events, occurring only after accumulation of MP:GFP in aggregate bodies and on MT in the target cell. MPNT-1:GFP localizes to MT but does not target to Pd nor does it move cell to cell. The spread of transiently expressed MPTMV:GFP in leaves of transgenic plants that produce MPNT-1 is reduced, and targeting of the MPTMV:GFP to the cytoskeleton is inhibited. Although MPTMV:GFP targets to the Pd in these plants, it is partially impaired for movement. It has been suggested that MPNT-1 interferes with host-dependent processes that occur during the intracellular targeting program that makes MP movement competent.

Cucumis sativus↗
PubMed2001

Pseudoventricular fibrillation.

A case of atrial fibrillation with asystole was diagnosed as ventricular fibrillation because of the autogain feature of the electrocardiographic monitor. Direct current shock therapy was withheld only because the patient regained consciousness.

Aged↗
PubMed2001

An evaluation of endodontically treated vertical root fractured teeth: impact of operative procedures.

Vertical root fractures of endodontically treated teeth are a frustrating complication that leads to extraction. The aim of the current survey was to evaluate the role of operative procedures in the etiology of this complication. A total of 154 endodontically treated vertical root fractured teeth were cleaned and washed after extraction and maintained in individual vials. Periapical radiographs before extraction, clinical findings and previous operative procedures were recorded. A post was observed in 95 teeth (61.7%), with 66 of these ending at the coronal third of the root. Most were screw posts of the Dentatus type (n = 64) and tapered cast posts (n = 14). A full crown was observed in 118 teeth, and 65 of these (55%) were extracted between 1 to 5 yr after final restoration. In 24 crowned teeth extraction was conducted within 1 yr after restoration and in 28 teeth after >5 years. It was concluded that post placement and root canal treatment are the major etiological factors for root fractures. Because signs and symptoms can appear years after the operative procedures in the root have been completed, coronal restorations would not interfere with the correct clinical diagnosis of vertical root fractures. Frequent recalls are recommended to diagnose vertical root fractures early, especially in susceptible teeth, such as premolars and mesial roots of mandibular molars.

Bicuspid↗
PubMed2001

Altered glycogen synthase and phosphorylase activities in skeletal muscle of tetraplegic patients.

Despite marked differences in both the extent of physical activity and in muscle metabolism and structure between tetraplegic and control subjects, the glycogen content in the skeletal muscle of both groups is similar. We determined whether this similarity could be explained by the activities of key enzymes of glycogen metabolism. Muscle biopsies were analysed for glycogen synthase (GS) and glycogen phosphorylase (GP) activities, as well as for metabolites. Glycogen content did not differ significantly between the two groups. Total glycogen synthase activity was reduced by almost 60 % in tetraplegics (P < 0.01), whereas total phosphorylase activity did not differ between groups. GS fractional activity did not differ between groups, whereas phosphorylase fractional activity (-/+ AMP) was significantly higher in the tetraplegics (0.08 +/- 0.01, control; 0.25 +/- 0.02, tetraplegics; P < 0.001). Neither uridine diphosphate (UDP)-glucose nor glucose 6-phosphate (G-6-P) content in muscle differed significantly between groups. These data demonstrate that, in tetraplegics, muscle glycogen content is preserved despite decreases in GS activity and increases in phosphorylase fractional activity. Muscle paralysis has differential effects on the activities of GS and GP. Experimental Physiology (2001) 86.2, 205-209.

Adult↗