Impaired polyglutamylation of methotrexate as a cause of resistance in CCRF-CEM cells after short-term, high-dose treatment with this drug

Two methotrexate-resistant sublines, CCRF-CEM R3/7 and CCRF-CEM R30/6, were selected from the human leukemia T-lymphoblast cell line, CCRF-CEM, after repeated exposures (7 and 6 times, respectively) for 24 h to constant concentrations (3 and 30 microM) of the drug. Analysis of the mechanism of resistance revealed no differences in levels of dihydrofolate reductase activity, its binding affinity for methotrexate, or in methotrexate transport between the CCRF-CEM parent and methotrexate-resistant cell lines. The development of resistance to methotrexate was associated with a marked decrease in the intracellular level of methotrexate polyglutamates. Although the resistant sublines were able to form substantial amounts of folate polyglutamates when measured with [3H]folic acid, the level of polyglutamates formed was decreased to about 50% of that formed by the parent cell line. No qualitative differences in folate polyglutamates formed were noted between the parental and resistant sublines. This is the first example of a cell line which displays resistance which is solely attributable to defective methotrexate polyglutamate synthesis.

Pancreatic carcinoma associated with chronic calcifying pancreatitis in Taiwan: a case report and review of the literature

A 62-year-old Chinese woman suffering from pancreatic carcinoma coexisting with chronic calcifying pancreatitis is reported. Ultrasonography and computed tomography disclosed multiple intraductal calcifications in the pancreatic head and body and a tumor at the tail. Laparotomy revealed cancerous peritonitis in addition to verifying the presence of calcifications at the head and body and a cancer at the tail. Histology confirmed adenocarcinoma. The incidence of pancreatic carcinoma in chronic calcifying pancreatitis varied from 0.8 to 25% in a thorough review of the literature. It is emphasized that patients with chronic calcifying pancreatitis should be closely followed for detection of possible coexisting pancreatic malignancies.

Trimetrexate: a second generation folate antagonist in clinical trial

Trimetrexate is a promising new lipophilic antifolate with antitumor and antimicrobial activity, which is currently undergoing clinical trials. It differs from methotrexate in its transport and intracellular retention, and may be useful against tumors resistant to methotrexate because of impaired transport or deficient polyglutamylation. In preclinical studies, it has demonstrated a broader spectrum of antitumor activity than methotrexate, and appears to have synergistic antitumor activity when combined with a number of other agents. In clinical trials, the primary toxicity has been hematologic, with rapid recovery and no evidence of cumulative dose effect. Nonhematologic toxicity has been sporadic. Preliminary results of phase II trials indicate activity against breast, non-small-cell lung, and head and neck tumors. In addition, trimetrexate with simultaneous leucovorin rescue appears to be a promising new treatment for pneumocystis pneumonia in AIDS patients, with minimal toxic side effects.

Clinicopathologic studies of asymptomatic HBsAg carriers: with special emphasis on carriers older than 40 years

To investigate the clinicopathologic features of asymptomatic carriers of hepatitis B surface antigen (HBsAg), liver biopsies were obtained in 140 carriers followed-up for more than 6 months. They included 47 older than 40 years and 75 with elevated SGPT values at least once during the follow-up period. Among the 93 carriers younger than 39 years, milder histologic changes than chronic persistent hepatitis (CPH) were seen in most of those with normal SGPT values, while more severe histologic changes (chronic lobular hepatitis, chronic active hepatitis and active cirrhosis) were found in 18 out of 50 with elevated SGPT values. In contrast, when the carriers were more than 40 years of age, the histologic liver changes became "bipolar", i.e., either very mild or quite severe, since among 47 subjects in this group, 37 (79%) had hepatic lesions milder than CPH, and the remaining 10 (21%) had cirrhosis. The positive rate of hepatitis B e antigen (HBeAg) was not significantly different among those with milder and those with more severe histologic changes in the younger group. However, that of the older carriers was significantly higher among those with liver cirrhosis (50% vs. 16.2%, p less than 0.05). The results imply that, in Taiwan where chronic HBsAg carriage usually occurs in early childhood, a poorer prognosis may exist in asymptomatic HBsAg carriers when HBeAg persists beyond the age of 40.

Phase I studies with trimetrexate: clinical pharmacology, analytical methodology, and pharmacokinetics

Twenty-two patients with advanced solid tumors were treated with a quinazoline folate antagonist, trimetrexate, to determine the toxicity spectrum, the maximal tolerated dose, and the pharmacokinetics of the drug. Negligible toxicity was seen with single doses of 10-70 mg/m2 given as a 1-h infusion. Single doses of 120 mg/m2 infused over 1 h caused moderate to grade 4 toxicity in five of nine patients treated. Two patients who had no toxicity at this level were escalated to a dose of 213 mg/m2 with mild to moderate toxicity. The primary dose-limiting toxicity was myelosuppression. Moderate transaminase elevations, rash, anorexia, nausea and vomiting, and mucositis were occasionally seen. Although there was variation in dose tolerance to this drug, with selected patients able to tolerate higher doses, we consider 120 mg/m2 every 2 weeks to be the maximal tolerated dose, and the recommended Phase II starting dose. Trimetrexate plasma concentration-time curves were best described as biphasic (N = 9) or triphasic (N = 5) in form. The half-life of the terminal elimination-phase was 16.4 h. The mean residence time was 17.8 h. The volume of distribution of the plasma compartment and the volume of distribution at steady-state were 0.17 and 0.62 liter/kg, respectively. Plasma clearance was 53 ml/min. Plasma concentrations as determined by dihydrofolate reductase enzyme inhibition assay and high-performance liquid chromatography were initially identical, but diverged at later times. Divergences were seen also in urinary recovery as determined by the two methods. Both results suggest the appearance of metabolite(s) of trimetrexate which can inhibit dihydrofolate reductase. Measurable objective solid tumor responses were not seen in this Phase I study, although three patients with colon cancer had stable disease lasting 18, 26, and 26 weeks, respectively.

Noninvasive diagnosis of advanced pancreatic cancer by real-time ultrasonography, carcinoembryonic antigen, and carbohydrate antigen 19-9

One-hundred-forty patients with clinical impression of pancreatic cancer were examined prospectively with three noninvasive tests: real-time ultrasonography, determination of serum carcinoembryonic antigen (CEA), and carbohydrate antigen (CA 19-9). Among them, 24 (17.1%) patients were found to have pancreatic cancer. The sensitivity of ultrasonography, CEA, and CA 19-9 was 72.9%, 70.8%, and 83.3%, respectively; the specificity was 94.0%, 77.6%, and 90.5%, respectively, and the diagnostic accuracy was 91.4%, 76.4%, and 89.3%, respectively. The combination of ultrasonography and determination of serum CA 19-9 had better sensitivity (95.8%), comparable specificity (84.5%), and comparable diagnostic accuracy (86.4%) to any individual test alone or any other combination. It was suggested that combined use of real-time ultrasonography and determination of serum CA 19-9 provided excellent noninvasive screening for patients suspected of having pancreatic cancer.

Subcellular fractionation of wheat leaf protoplasts by centrifugal elutriation

A new method using centrifugal elutriation for subcellular fractionation of plant cells has been developed. This method takes advantage of the fact that particles sedimenting in a gravitational field can be eluted by flow against the field. A wheat protoplast homogenate was fed into an elutriation rotor spinning at high speed and the flow rate into the rotor was gradually increased. The smaller and less dense materials such as mitochondria, microbodies, endoplasmic reticulum, and cytoplasm were elutriated earlier than the larger and denser nuclei and chloroplasts. The intact chloroplasts, free of mitochondria, microbodies, endoplasmic reticulum, and cytoplasm, could be obtained within 40 min following the rupture of protoplasts. The chlorophyll-free mitochondria could be obtained within 80 min.

Acupuncture for the induction of cervical dilatation in preparation for first-trimester abortion and its influence on HCG

Cervical dilatation in preparation for first-trimester abortion using acupuncture at loci SP6 and LI4 was studied in 20 patients, who were compared to a control group in whom no preparation was used. Ninety percent of the patients had successful acupuncture procedures. As judged by Hegar dilators, the increase in cervical dilatation in those 18 patients was significantly greater than in the controls. No significant side effects were observed. The effect of acupuncture on serum human chorionic gonadotropin (HCG) as a pregnancy marker was evaluated in 12 patients. No statistically significant difference in the change in HCG was noted in terms of the controls, indicating an absence of abortifacient activity with acupuncture.

Hepatocellular carcinoma: US evolution in the early stage

To study the sonographic evolution of hepatocellular carcinoma (HCC) in its early stage, 26 HCCs in 24 patients were observed regularly with real-time ultrasound for a period of 90 to 691 days. In the beginning, 21 tumors were hypoechoic, two isoechoic, and three diffusely hyperechoic. On follow-up, two of the 21 initially hypoechoic HCCs remained the same echodensity, 12 increased in internal echoes but were still hypoechoic, one became isoechoic, four changed to hyperechoic, and the remaining two shifted from hypoechoic to isoechoic and then to hyperechoic. The two initially isoechoic HCCs also gained echogenicity and became hyperechoic. By contrast, the three initially hyperechoic HCCs kept the same echo patterns. The "acquired" hyperechoic HCCs were inhomogeneous in echodensity and larger in size whereas the three originally hyperechoic HCCs were homogeneous and smaller. It is concluded that most small HCCs evolve progressively from hypoechoic to isoechoic and then to inhomogeneously hyperechoic patterns as they grow; a few HCCs have diffusely high echogenicity from the beginning and retain the same features thereafter.

Prolactin production by explants of normal, luteal phase defective, and corrected luteal phase defective late secretory endometrium

The production of prolactin by explants of late secretory endometrium has been correlated with the extent of decidual differentiation. This correlation is strengthened by the observation that luteal phase defective endometrium produces less prolactin than normal control endometrium in a 24-hour in vitro culture system. In the present study the prolactin production by explants of normal, luteal phase defective, progesterone-corrected luteal phase defective, and clomiphene- or follicle-stimulating hormone/luteinizing hormone-corrected luteal phase defective late secretory endometrium was measured over 96 hours at 24-hour intervals. Progesterone in physiologic concentrations was added to the culture medium to maintain tissue integrity and prolactin synthesis. The prolactin production of normal late secretory endometrium rose over 96 hours under progesterone stimulation. The luteal phase defective endometrium produced significantly less prolactin under the same conditions. Histologically proven corrected luteal phase defective endometrium, regardless of treatment method, produced prolactin not different from the normal controls of the same dates. From these results it is concluded that histologic correction of luteal phase defective endometrium is associated with a corresponding biochemical correction with use of prolactin as a metabolic marker. The findings also strongly support timed endometrial biopsy as the method of diagnosis and evaluation of treatment of luteal phase defect.

Penile neuropathy in insulin-dependent diabetes mellitus

The dorsal nerve of the penis has been linked closely to penile erection and response. We measured the nerve conduction velocity of the dorsal nerve of the penis, latency of the bulbocavernosus reflex and pudendal evoked potential in 23 normal men and 20 insulin-dependent diabetics with impotence. The conduction velocity of the dorsal nerve of the penis was significantly slower in diabetic than in normal men and passive gentle elongation of the penis by weight stretching enhanced the slowing. In contrast, the bulbocavernosus reflex and pudendal evoked potential showed no significant differences between the 2 groups. We demonstrate the potential usefulness of measurement of the conduction velocity of the dorsal nerve of the penis in the detection of penile neuropathy.

Short term effect of low doses of tri-iodothyronine on proximal tubular membrane Na-K-ATPase and potassium permeability in thyroidectomized rats

Tri-iodothyronine (T3), even when administered for short time and at low doses, induces a large increase in the isotonic fluid reabsorption (Jv) in proximal tubules of thyroidectomized rats (TX). In order to investigate the role of the Na-K-ATPase in this process, we measured the Na-K-ATPase activity in early proximal convoluted tubules (S1) and proximal straight tubules (S2) microdissected from TX rats and rats treated with low doses of T3 (10 micrograms/kg body wt), either for 3 days (TX + 3T3) or for 7 days (TX + 7T3). In both segments no changes in Na-K-ATPase activity were found in TX + 3T3 rats versus TX rats, while an increase was registered in TX + 7T3 rats. Using micropuncture techniques, Jv measured on the same tubular segments increased by 68% in TX + 3T3 rats versus TX. Thus, no correlation between Jv and Na-K-ATPase activity measured in vitro could be detected after short term treatment of TX rats with T3. Na-K-ATPase activity in vivo is also regulated by the potassium permeability of the membrane, which might be altered by tri-iodothyronine. This hypothesis was tested by perfusing intraluminally and peritubularly proximal tubules of TX rats with the K ionophore, valinomycin (1 microgram/ml). In the dual perfusion experiments valinomycin elicited 40% of the action induced on Jv by 3 days treatment with T3. On the other hand, no further increase in Jv was recorded when valinomycin was applied in TX rats pretreated with T3.(ABSTRACT TRUNCATED AT 250 WORDS)

Structural state of the Na+/D-glucose cotransporter in calf kidney brush-border membranes. Target size analysis of Na+-dependent phlorizin binding and Na+-dependent D-glucose transport

Target sizes of the renal sodium-D-glucose cotransport system in brush-border membranes of calf kidney cortex were estimated by radiation inactivation. In brush-border vesicles irradiated at -50 degrees C with 1.5 MeV electron beams, sodium-dependent phlorizin binding, and Na+-dependent D-glucose tracer exchange decreased exponentially with increasing doses of radiation (0.4-4.4 Mrad). Inactivation of phlorizin binding was due to a reduction in the number of high-affinity phlorizin binding sites but not in their affinity. The molecular weight of the Na+-dependent phlorizin binding unit was estimated to be 230 000 +/- 38 000. From the tracer exchange experiments a molecular weight of 345 000 +/- 24 500 was calculated for the D-glucose transport unit. The validity of these target size measurements was established by concomitant measurements of two brush-border enzymes, alkaline phosphatase and gamma-glutamyltransferase, whose target sizes were found to be 68 570 +/- 2670 and 73 500 +/- 2270, respectively. These findings provide further evidence for the assumption that the sodium-D-glucose cotransport system is a multimeric structure, in which distinct complexes are responsible for phlorizin binding and D-glucose translocation.

Chromatofocussing and centrifugal reconstitution as tools for the separation and characterization of the Na+-cotransport systems of the brush-border membrane

Chromatofocussing was used for the separation of brush-border membrane proteins from calf kidney into 4 or 5 fractions over the pH range 4.0 to 7.4. These fractions were reconstituted into proteoliposomes by gradient centrifugation. Determination of the sodium-dependent solute uptake by proteoliposomes reconstituted from different chromatofocussed fractions showed that the sodium-D-glucose cotransport system was present in the fraction eluted between pH 5.3 and 5.8, and that the sodium-phosphate cotransport was present in fractions eluted between pH 4.6 and 5.3 and between pH 5.8 and 6.6, sodium-alanine cotransport could be detected in almost all fractions. Marker enzymes of the brush-border membrane, such as alkaline phosphatase, gamma-glutamyltransferase and aminopeptidase M etc. were also found to be eluted at pH 7.0-7.4, 4.0-4.1 and 5.6-5.8, respectively. These results suggest that chromatofocussing is a promising tool for the separation of membrane proteins and for pre-purification of the sodium-D-glucose cotransport system. It can be further concluded that the sodium-dependent phosphate transport across the brush-border membrane is not dependent upon alkaline phosphatase activity.

Measurement of the conduction velocity of the dorsal nerve of the penis

We describe an orthodromic nerve conduction technique of the dorsal nerve of the penis in 27 normal men. The mean compound nerve action potential was 12.0 plus or minus 6.1 microV. The nerve conduction velocity was 24.4 plus or minus 3.2 milliseconds when the penis was at rest. Gentle stretch of the penis with a 1-pound weight increased the conduction velocity to 33.0 plus or minus 3.8 milliseconds. Since the dorsal nerve of the penis has an important role in erection the new methodology may be useful in the evaluation of male impotence.