Regulation of carnosine metabolism: the subcellular localization of carnosinase in liver

We studied the subcellular localization of carnosinase (EC 3.4.13.3) in rat liver. The liver homogenate was fractionated by differential centrifugation into a nuclear (N), a mitochondrial (M), a lysosomal (L), a microsomal (P) and a soluble (S) fraction. The purity of different subcellular fractions was established by using different markers. The carnosinase activity in different fractions was measured by fluorometric determination of L-histidine produced using carnosine as a substrate. The intracellular distribution of carnosinase was very similar to that of lactate dehydrogenase with the highest relative specific activity of enzyme being observed in the soluble fraction. These results indicate that carnosinase enzyme is primarily located in the soluble (cytoplasmic) fraction of rat liver.

Oxygen free radicals and heart failure

We hypothesize that oxygen free radicals are involved in the genesis and maintenance of volume and pressure overload heart failure. Pressure and volume overload would produce myocardial ischemia. During ischemia there will be an increase in xanthine and xanthine oxidase; and a decrease in the superoxide dismutase and glutathione peroxidase activity leading to an increase in the oxygen free radicals. A decrease in the cellular pH during ischemia would release phospholipase which would, in turn, release arachidonic acid from phospholipids. Leukotrienes and prostaglandins will be synthesized through arachidonic acid metabolism. During this synthesis not only oxygen free radicals will be produced but also there will be formation of leukotriene, LTB4, which is known to activate neutrophil and hence increased secretion of oxygen free radicals. Increased circulatory catecholamines due to compensatory mechanism would also lead to an increase in the oxygen free radicals. Oxygen free radicals are known to depress Ca++ binding and uptake of sarcoplasmic reticulum which would lead to a decrease in the myocardial contractility. We have shown that oxygen free radicals depress cardiac function and cardiac contractility. It is, therefore, suggested that oxygen free radicals might be involved in the development of heart failure. The use of agents that reduce the amount of oxygen free radicals would be of value in the prevention and treatment of heart failure.

Hepatocellular carcinoma in a long-term survivor of acute lymphocytic leukemia

Hepatocellular carcinoma (HCC) occurred in a 28-year-old woman treated for acute lymphocytic leukemia (ALL) with methotrexate (MTX) and 6-mercaptopurine (6-MP), off all therapy for 15 years, who was also heterozygous for alpha-1 antitrypsin (alpha-1 AT) deficiency. MTXD is responsible for the development of HCC in this patient. The literature concerning the incidence of HCC in patients treated with MTX and 6-MP and in alpha-1 antitrypsin deficiencies is reviewed.

Evaluation and assessment of high sensitivity thyrotropin methods as an index for thyroid function

We report the evaluation of four new commercially available sensitive assay kits for determination of thyrotropin (TSH) and their clinical utility in normal subjects and patients with thyroidal and non-thyroidal illnesses. The sensitivity for the reliable detection of serum TSH by these methods ranged from 0.1-0.4 mU/L and their decreasing order was : NML greater than Serono greater than Abbott EIA greater than Hybritech. The coefficient of variation ranged from 2.0-5.8% for intra-assay and 2.3-8.6% for interassay at different concentration levels. Patients studied (n = 130) were assigned into four groups on the basis of the serum thyroxine value and their clinical findings. In total, there were 17 discrepancies (five with Hybritech, three with NML, five with Abbott EIA, and four with Serono) in making the correct diagnosis using these sensitive TSH methods as a single diagnostic test. These discrepancies were mainly in the same patients who were clinically euthyroid but had subnormal TSH values. There were no discrepancies in making the correct diagnosis for patients with hyperthyroidism or hypothyroidism using these sensitive TSH methods. Our observations indicate that the sensitive TSH methods are reliable in measuring subnormal levels and may be used to detect hyperthyroidism without affecting in any way their value in detecting hypothyroidism.

Value of free thyroxine (FT4), free triiodothyronine (FT3), and sensitive thyrotropin (TSH) assay in the assessment of optimal thyroxine therapy

We describe a sensitive thyrotropin (TSH) assay in the evaluation of thyroxine replacement therapy. Patients taking varying amounts of L-thyroxine replacement doses were studied using a thyrotropin-releasing hormone (TRH) test and a sensitive TSH assay as the indices of optimal replacement therapy. There were no differences in the mean thyroxine doses of those patients who had a normal TRH response and those who had a flat response. Similarly there were no significant differences in the serum free thyroxine (FT4), free triiodothyronine (FT3), or total triiodothyronine (TT3) levels between these two groups. The patients in both groups had normal basal serum TSH values as measured by a standard, HTSH RIABEAD (Abbott) method. However, serum TSH values, as measured by a sensitive TSH3 MAIACLONE (Serono) immunoradiometric method, were subnormal in all patients with flat TRH responses. The TSH (Serono) assay provided the best single blood test of optimal thyroxine replacement.

Simultaneous renal cell carcinoma and squamous cell carcinoma of kidney

A unique case of a collision tumor of the kidney composed of a renal cell carcinoma and a squamous cell carcinoma is reported. Although a few cases of combined tumors of the kidney have been reported previously, we were unable to find any similar case in the literature. Squamous cell carcinoma of the kidney usually behaves aggressively. Early diagnosis and surgical treatment before the tumor has extended beyond the capsule offer the best hope of cure.

Effective multimodality treatment for advanced epidermoid carcinoma of the female genital tract

Fifteen patients with advanced or recurrent squamous-cell carcinoma of the cervix, vulva, vagina, and urethra were treated with simultaneous combination chemotherapy (5-fluorouracil infusion and mitomycin C) and radiotherapy (3,000 rad for a period of three weeks). Three to four weeks after completion of radiotherapy, 13 of 15 patients achieved partial or complete tumor shrinkage. Nine of 15 patients are alive, eight of whom (at a median follow-up time of 24 months) have no evidence of disease. The longest survival time was 45 + months. There was minimal toxicity associated with this therapy. The results of this pilot study suggest that the simultaneous administration of radiation and chemotherapy is an effective method of treatment of advanced female genital tract carcinoma.

Digoxigenin biotransformation

Two healthy subjects took 3H-digoxigenin-12 alpha and unlabeled digoxigenin. Metabolites were assayed by high-pressure liquid chromatography (HPLC) in serum and urine. Of the tritium activity in the serum at 30 min, less than 26% chromatographed with digoxigenin; the rest chromatographed as metabolites, most of which were polar. The main polar metabolites identified were glucuronides of 3-epidigoxigenin. An important route of biotransformation to polar metabolites appears to be from 3 beta-digoxigenin through 3-keto-digoxigenin to 3-epidigoxigenin. Several HPLC peaks remain unidentified. There was extensive cross reactivity between metabolites and antisera to digoxin. The digoxigenin route of digoxin biotransformation to polar metabolites may be important in some patients receiving digoxin and such metabolites could contribute an important fraction to the serum digoxin concentration measured by radioimmunoassay.

Chemotherapy for head and neck cancer relapsing after radiotherapy

Thirty-nine patients (28 men and 11 women, ages 43 to 83 years) with advanced head and neck epidermoid carcinoma (33 had relapsed from previous radiotherapy) were treated with a three-day bleomycin administration (30 by continuous intravenous infusion and nine by subcutaneous route) followed on the fifth day by intravenous administration of cyclophosphamide + methotrexate + 5-fluorouracil (Bleo-CMF). This drug schedule was based on the cell cycle synchrony principle. Twenty-one of 39 patients (54%) responded (seven complete, 14 partial remission) lasting from 4 to 20 months. The median duration of survival for complete remission, partial remission, and disease progression was 15, ten, and four months, respectively. The Bleo-CMF was well tolerated with minimal toxicity. The effectiveness of this regimen in previously irradiated patients compels us to pursue its application in a randomized study as an adjuvant for Stages III and IV head and neck cancer following maximum eradication of the local disease by surgery and/or radiotherapy.

Influence of gastric pH on digoxin biotransformation. II. Extractable urinary metabolites

High-performance liquid chromatography (HPLC) analysis was performed on methylene chloride extracts of urine from six subjects after administration of 3H-digoxin-12 alpha and unlabeled digoxin by nasogastric tube under four conditions: pentagastrin and control saline infusions, each in the supine and ambulatory states. There were no differences with change in position. With pentagastrin stimulation of acid secretion, there was extensive intragastric hydrolysis, mainly to digoxigenin; there was further extensive biotransformation leading to an increase in both extractable and unextractable metabolites in urine, particularly the latter. In the first 5 hr mean digoxin was only 17% and unextractable metabolites were 54% of total urine radioactivity. Extractable radioactivity was found under HPLC peaks with retention times of digoxin, digoxigenin, and its mono- and bis-digitoxosides. There were also three other peaks that were not identified; two correlated with gastric H+ activity and with the peak for digoxigenin, which is probably their precursor since similar peaks were found after ingestion of digoxigenin. The third unidentified peak eluted immediately after the digoxin, with which it correlated; it may have a close structural relationship to digoxin. Gastric acid stimulation induced a major increase in the production of urinary metabolites and may prove a useful model for the study of digoxin biotransformation, which is not yet well defined.

Comparison of infrared and wet chemical analysis of urinary tract calculi

Infrared analysis of urinary tract calculi using the system of interpretation of spectra of Oliver and Sweet [1] was compared with qualitative wet chemical analysis. This method of interpretation could be learned quickly and gave reproducible results, but had some limitations. Advantages of the infrared procedure include greater reproducibility. 1-mg sample size, greater sensitivity for oxalate and more uniform sensitivities. Minimum detectable amounts of reference standards varied roughly within 1 order of magnitude, compared with a range of 10(5) for wet chemical procedures. The comparable sensitivity for oxalate and phosphate permits a semi-quantitative approach for infrared. The main problems relate to the detection of magnesium ammonium phosphate and carbonate apatite, and wet chemical tests are recommended in addition, when these compounds are suggested. Calculi from 308 patients were analyzed by infrared. With this system of interpretation of spectra, infrared is considered to be a major advance in methodology for analysis of urinary tract calculi in the clinical laboratory, compared with qualitative wet chemical procedures.

Loading dose of digoxin in renal failure

1 Twenty-two dialysis dependent patients received an intravenous loading dose of digoxin of 10 microgram/kg and the mean +/- s.d. serum digoxin concentration 24 h later was 1.5 ng/ml +/- 0.4 (range 0.8--2.1 ng/ml). No evidence of toxicity was observed. 2 The average apparent volume of distribution of digoxin in dialysis dependent patients was found to be reduced by about one third compared with that reported for individuals with normal renal function, but there was great variation. 3 An appropriate intravenous loading dose of digoxin in most patients with advanced renal failure is 10 microgram/kg.

Influence of gastric pH on digoxin biotransformation. I. Intragastric hydrolysis

3H-digoxin-12 alpha and unlabeled digoxin were administered down a nasogastric tube and digoxin, digoxyigenin and its mono- and bis-digitoxosides, and pH were assayed in gastric fluid of 6 healthy subjects at intervals for 90 min each under 4 conditions: pentagastrin infusion 6 micrograms/kg/hr with the subjects ambulatory and supine, and saline infusion ambulatory and supine. Intragastric hydrolysis occurred at roughly the same rate as reported in vitro. At 90 min, an average of 12.5% of the radioactivity that remained in the gastric fluid was recovered as digoxin for the 2 conditions when pentagastrin was infused, compared with 52.5% for th 2 conditions when saline was infused. The main glycosidic metabolite was digoxigenin and the amount correlated closely with the hydrogen ion activity in gastric fluid at 90 min (r = 0.83, p less than 0.01). Only minor differences were found between the supine and ambulatory conditions. The clinical significance of these results remains to be determined.

Naked megakaryocyte nuclei revisited

Bone marrow smears from 35 patients with various neoplasms and from 32 control patients were examined for the presence and percentage of naked megakaryocyte nuclei (NMN). The percentages of NMN in the two groups did not significantly differ. We conclude that the enumeration of NMN is of no value as a diagnostic test of malignancy.

Localization of phosphate-independent glutaminase in the brush border of rat kidney cortex

A microsomal fraction that contains the highly enriched activities of NADPH – cytochrome c reductase, 5′-nucleotidase, phosphate-independent glutaminase, and alkaline phosphatase was isolated by differential centrifugation from rat kidney cortex. Continuous sucrose density gradient studies on this fraction have shown that the distribution pattern of phosphate-independent glutaminase is identical with that of alkaline phosphatase and the specific activity of these enzymes in peak fractions were 13- to 17-fold higher than in the whole homogenate. These results indicate that the phosphate-independent glutaminase is localized in the brush border of rat kidney cortex. The enzyme is truly membranous as it could not be removed by sonication, salt treatment, or pH alterations.