Dependence of measured ionized calcium on protein concentration as measured by three ion-selective electrodes

A positive effect of protein on the measurement of ionized calcium in serum by ion-selective electrodes (ISEs) has been previously reported and the present study confirms this finding. Ionized calcium in serum was measured in the presence of increasing protein concentrations induced by venous stasis in 17 healthy volunteer subjects. Ionized calcium was measured using two commercial analysers, a Radiometer ICA2 analyser and a Baker Analyte+2 analyser, and a calcium cell devised by Covington for the calcium reference method (CRM). Both commercial analysers used charged ionophores and the CRM used a neutral carrier ionophore in the selective membrane. A small but significant rise in ionized calcium with increasing protein was measured on all analysers. Substitution of isotonic KCl for saturated KCl in the reference electrode of the CRM resulted in significantly reduced values for ionized calcium in paired serum samples when measured using the isotonic salt bridge. This study supports the premise that the positive effect of protein is related to the salt bridge concentration of the reference electrode rather than the ISE membrane composition.

Ultrasound-guided hepatic cryosurgery in the treatment of metastatic colon carcinoma. Preliminary results

Cryosurgery, the in situ freezing of cancer, has been proposed in the past as a possible treatment for unresectable hepatic tumors. Its advantage lies in the fact that it is a very focal treatment sacrificing less normal tissue than surgical resection, allowing treatment of multiple lobes. Because cryosurgery does not affect large vessels, tumors in difficult locations, such as adjacent to the inferior vena cava (IVC), can be treated. With the use of intraoperative ultrasound to place the cryoprobes and monitor the freezing process, 18 patients with unresectable metastatic colon carcinoma confined to the liver were treated. Of the 18 patients treated, 4 (22%) are in complete remission as determined by computed tomography (CT) scans and carcinoembryonic antigen (CEA) levels, with a mean follow-up of 28.8 months. Four patients (22%) were not adequately treated at the time of cryosurgery. The number of lesions frozen in each patient ranged from 1 to 12, with a mean of 6 lesions. Fourteen patients had bilobar disease; three patients had previous right lobectomies with recurrences in their remaining left lobes prior to cryosurgery, and one patient had unilobar disease. Mean survival of the 14 cases with recurrence was 21.4 months, with 2 of the 14 still alive. Ultrasound-guided hepatic cryosurgery appears to be an effective treatment for metastatic colon carcinoma to the liver that is unresectable (including patients with bilobar and multiple lesions). These preliminary results indicate that the procedure warrants further study.

Adsorptive stripping voltammetric determination of pipemidic acid in human urine

The electrochemical behaviour of pipemidic acid (8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)-pyrido[2,3-d]pyrimidine-6- carboxylic acid), a well known antimicrobial agent used for urinary infections, was investigated by linear-sweep, differential-pulse and square-wave voltammetry at a hanging mercury drop electrode. Two reduction processes were observed in Britton-Robinson buffers at acid pH, whereas only one or two processes were observed in alkaline solutions, dependent on the pH of the buffer employed. Adsorptive effects were used to accumulate the drug on to the electrode. The adsorbed species were measured voltammetrically by using a cathodic process appearing at -0.76 V in 0.1 M HCIO4. Linear calibration graphs were obtained in the range 2.5 x 10(-9)-2.0 x 10(-7) M. A simple procedure of extraction was employed for the determination of the drug in urine samples.

Cirrhosis in the trauma victim. Effect on mortality rates

To evaluate the impact cirrhosis has on survival the records of 40 cirrhotic trauma victims from the registries of two Level 1 trauma centers were reviewed and probability of survival calculated using the TRISS methodology. Mechanism of injury, anatomic location, involvement of single or multiple sites, presence of ascites, elevations in serum glutamic oxaloacetic transaminase (SGOT), alkaline phosphatase, serum bilirubin, prothrombin time (PT), and hypoalbuminemia were tabulated for each patient. Contingency tables were created for injury and hepatic parameters, as related to survival, and subjected to chi square analysis. Loglinear analysis was performed on all significant parameters to evaluate the independent effects of injury characteristics and hepatic insufficiency on survival. Predicted survival was 93%; observed survival was 70% (Z = -6.92; p less than 0.001). Cause of death was multiple-system organ failure (9) and closed head injury (3). Admission markers of poor outcome included one or more of the following: ascites, elevated PT or bilirubin, history of motor vehicle accident, multiple trauma, or blunt abdominal trauma requiring laparotomy. Loglinear analysis revealed that the presence of ascites, elevated PT, or bilirubin, further diminished the rate of survival for any individual injury characteristic. We concluded that survival among cirrhotic trauma victims was significantly lower than predicted. In addition the presence of hepatic insufficiency further diminishes survival, regardless of the injury sustained.

Comparison of a calixarene-based ion-selective electrode with two automated analyzers for the clinical determination of sodium in blood plasma

Neutral-carrier ion-selective electrodes based on methyl p-t-butylcalix[4]aryl acetate have been prepared that are responsive to sodium ions. The miniaturized catheter-type electrodes were obtained by dip-coating their porcelain tips in a PVC membrane cocktail. Examination of the general performance of the electrodes revealed excellent characteristics in terms of Nernstian response, selectivity, stability, reproducibility and response time. The results from the indirect potentiometric assessment of a large number of plasma samples with the electrodes showed a good correlation with the results from two automated analyzers (Technicon Smac 3, Hitachi 704) and with flame photometric data. Although inconsistencies were observed in the measurement of some plasma samples, the variance seemed to be method-dependent, and the overall performance of the electrodes showed promise as an alternative to the sodium glass electrode. Some factors influencing the standard potential of the measuring cell are discussed as a source of error.

The effect of streptozotocin-induced diabetes on the neuroendocrine-male reproductive tract axis of the adult rat

Studies in the streptozotocin rat model for diabetes mellitus suggest that sexual dysfunction in these animals may result from diabetes-induced alterations of the neuroendocrine-reproductive tract axis. Our investigation was performed to better define the effects of diabetes on the neuroendocrine sex accessory organ axis in the male rat. Rats were rendered diabetic, and were either left untreated or treated with insulin, testosterone or both. Diabetes resulted in decreased body and reproductive organ weights, as well as diminished sperm counts and motility and prostatic acid phosphatase. Seminal fructose was increased. A significant decrease in serum LH, FSH and testosterone was noted. Insulin treatment of the diabetic rats restored serum gonadotropins, reproductive organ weight, sperm counts and motility, and seminal fructose to control levels. Prostatic weight and prostatic acid phosphatase levels remained abnormal. Testosterone restored the above mentioned parameters to control levels, with the exception of LH. Treatment with insulin and testosterone had a synergistic effect on spermatogenesis. A GnRH stimulation test demonstrated that pituitaries of diabetic animals had a blunted response, with diminished LH and FSH secretion. In the diabetic animal, there are both pituitary and testicular abnormalities which may be responsible for reproductive dysfunction.

Dentate granule cells in the rat hippocampal formation have the behavioral characteristics of theta neurons

Recordings were made from the dentate gyrus granule cell layer of freely-moving rats. The neurons recorded from the layer were divisible into 3 classes using a combination of electrophysiological and behavioral criteria; the duration of the extracellularly recorded unfiltered action potential provided the most reliable means of differentiating between cell types. Class I and class II neurons always fired in short duration single action potentials, while class III neurons had broader waveforms and occasionally were observed to fire complex spikes. As the most obvious behavioral correlate of class I and class II neurons was movement of the rat, these cells correspond to the theta cells of Ranck. Class III neurons for which a behavioral correlate was observed had the characteristics of the place cells described by O'Keefe. The neurons of classes I and II comprised 89% (56 of 63) of the total population sampled in the granule cell layer. Most of these neurons (49 of 56) discharged at short latency in response to a stimulus delivered via the perforant pathway; in contrast, none of the class III neurons observed were activated in this way. Horseradish peroxidase or Fast Green dye ejection through glass microelectrodes recording class I cell activity in urethane-anesthetized animals revealed the electrode tip to be in the granule cell layer in 27 of 27 cases. Six single class I neurons were also antidromically activated by a stimulus from an electrode placed in the hippocampal mossy fibers, and collision testing was successful in all cases. It is concluded that the dentate granule cells are theta cells.

Disproportionate expression of the two nonallelic rat insulin genes in a pancreatic tumor is due to translational control

The expression of the two nonallelic but highly homologous rat insulin genes (1 and 2) in a transplantable beta-cell tumor is found to be 10-fold higher for rat1 insulin than rat2 insulin, while in normal pancreatic tissue there are approximately equal amounts of each protein. No large sequence rearrangements of the genes were apparent by restriction analysis of the tumor DNA, and both genes were found to be specifically hypomethylated in the tumor as compared with other nonpancreatic tissue. Equivalent amounts of both insulin 1 and 2 precursor transcripts, as well as stable, mature mRNAs were detected in the tumor. However, two-dimensional gel analysis of immunoprecipitated rat1 and rat2 preproinsulins synthesized in vitro revealed a 10:1 ratio of rat1 to rat2 proteins. A 1:1 ratio was obtained when the tumor mRNA was treated in vitro with vaccinia virus capping extract, suggesting a structural modification at the 5' terminus of the rat2 mRNA. These results are discussed in the context of insulin regulation by glucose, shown to be due to translational control.

Management of chronic peritoneal catheter malfunction

This paper presents a modification of Tenckhoff's insertion procedure for chronic peritoneal dialysis catheters and reviews the results of a technique of management of catheter malfunction by manipulation which obviates the need for catheter replacement. 43 catheters in 33 patients were observed for no less than 1 year. Catheters which malfunctioned within 3 weeks benefited only marginally from manipulation. In those catheters which functioned for more than 3 weeks, manipulation extended mean survival time by 103% (8.5-17.3 months) and overall survival did not differ statistically from catheters not requiring manipulation. The technique is safe and simple and contributes to the effective management of patients undergoing chronic peritoneal dialysis.

Torso mounted electrocardiographic electrodes for routine clinical electrocardiography

An easily applicable lead system similar to that proposed by Mason and Likar in 1966 for stress electrocardiography provides quantitative and qualitative electrocardiographic information and diagnoses similar to those derived from the "standard" lead system using only torso placement of ten electrodes.

Persistent pancreatic glucagon but not insulin response to arginine in pancreatectomized dogs

Effects of total pancreatectomy on plasma glucagon, insulin and glucose responses to arginine were determined in 5 dogs. Portal vein and femoral artery samples were obtained in response to an arginine infusion (10 g/30 min) prior to, 1 h, 1 day and 1 week after pancreatectomy. Glucagon was measured using pancreatic-specific antiserum 30K (Unger, Dallas). Before pancreatectomy arginine significantly increased portal vein glucagon from 373 plus or minus 36 to 595 plus or minus 31 pg/ml and femoral artery levels from 233 plus or minus 28 to 342 plus or minus 74 pg/ml. Portal vein and femoral artery insulin concentrations of 74 plus or minus 21 and 17 plus or minus 3 muU/ml increased significantly to 173 plus or minus 64 and 31 plus or minus 7 muU/ml. Glucose levels did not change. One h after pancreatectomy, portal vein glucagon decreased to 121 plus or minus 15 pg/ml but increased to 230 plus or minus 42 pg/ml after arginine. Elevated blood glucose and the necessity for insulin treatment established the adequacy of pancreatectomy. Furthermore portal vein insulin levels were undetectable and unresponsive to arginine or a combination of glucose, glucagon, and tolbutamide 1 week after pancreatectomy. One day after pancreatectomy arginine significantly increased portal vein glucagon from 343 plus or minus 42 to 776 plus or minus 152 pg/ml. One week after pancreatectomy basal glucagon values were 374 plus or minus 30 in the portal vein and 360 plus or minus 49 in the femoral artery and responded to 1226 plus or minus 641 and 825 plus or minus 270 pg/ml, respectively, with arginine. Chromatography of plasma from one pancreatectomized dog on Sephadex G-50 after arginine stimulation revealed that much of the material cross-reacting with antibody 30K was eluted from the column earlier than either 125I-insulin or 125I-glucagon. In contrast, peak glucagon activity in plasma obtained from a normal human given arginine eluted from the column between the peak of 125I-insulin and 125I-glucagon; glucagon added to human plasma also was recovered in this same area between the 125I-insulin and 125I-glucagon peaks. These results suggest that some of the material that reacted with 30K antibody and which increased after pancreatectomy in response to arginine has a molecular weight greater than pancreatic glucagon. At autopsy no pancreatic tissue could be identified. Thus, after pancreatectomy, validated by absent insulin responses, the glucagon response to arginine was normal or increased. Since arginine is not thought to increase intestinal glucagon-like immunoreactive material, the source and nature of the material measured as glucagon after pancreatectomy is unknown, but may be important to any understanding of plasma glucagon measurements.