Pharmacokinetics of amlodipine in hypertensive patients undergoing haemodialysis.

OBJECTIVE: Amlodipine is a calcium antagonist of the dihydropyridine class. This study was performed to examine the single and multiple dose pharmacokinetics of amlodipine in hypertensive patients undergoing haemodialysis and to measure the index of accumulation during multiple dosage. An additional objective was to examine the dialysability of amlodipine by measuring its appearance in dialysate. METHODS: Seventeen hypertensive out-patients on haemodialysis were enrolled in this prospective, open, non-comparative phase-IV study. Fifteen patients completed the study. In the first part of the study, the patients were given a single oral 5-mg dose of amlodipine and blood samples taken 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 72 and 144 h later. After a 4-week wash-out period, the patients were given a daily 5-mg oral dose of amlodipine for 30 days. The trough levels of amlodipine were measured on days 8, 15, 22 and 29. On day 30, the total time course of amlodipine concentrations in plasma was measured, as in the first part of the study. In addition, on day 15, the concentrations of amlodipine in dialysate were measured at the same time as in blood. Blood pressure and heart rate were measured and adverse events monitored. Pharmacokinetic parameters [Cmax, tmax, kel and AUC(0-24)] were calculated for the single dose and for the dose on day 30 and the accumulation index calculated on the basis of AUC(0-24) and Cmax. RESULTS: The mean values of the single-dose pharmacokinetic parameters were as follows: Cmax 3.83 microg l(-1), tmax 5.01, AUC(0-24) 59.90 microg l(-1) h, kel 0.0177 h(-1). The mean accumulation index on the basis of AUC(0-24) was calculated as 3.70. Very low levels of amlodipine were detectable in dialysate fluid. The most frequently reported adverse events were hypertension, hypotension and muscle cramps. CONCLUSION: There are only minor differences in the pharmacokinetics of amlodipine between healthy subjects and hypertensive patients on haemodialysis. Comparison with literature values for healthy volunteers suggests that amlodipine is rapidly and extensively absorbed in the patient group. Amlodipine is essentially not dialysable. These findings do not indicate a need for dose adjustment in renal failure patients on haemodialysis.

The calcium-parathyroid hormone regulation in chronic renal failure investigation of its dynamic secretion pattern.

In patients with secondary hyperparathyroidism (HPT) caused by chronic renal failure (CRF), the pulsatility of parathyroid hormone (PTH) secretion and the relation of PTH to plasma Ca2+ concentrations were investigated. Intermittent hyper- and hypocalcemia was induced to study the deterministic reaction of the parathyroid glands. Compared to normal behaviour in CRF the pulsatility is lost. Yet the deterministic coupling between PTH and Ca2+ concentrations remains qualitatively the same though quantitatively it is exaggerated and varies depending on the subjects.

Parathyroid hormone secretion and serum calcium concentration--a deterministic view of its regulation.

In seven normal men we investigated the basal secretion of PTH by blood sampling in 30 sec intervals for estimation of intact PTH and at 2-min intervals for measurement of ionized calcium. In 4 of these subjects we also investigated the PTH-secretion under conditions of intermittent hypercalcemia and hypocalcemia. Our measurements demonstrate the existence of three time scales in the secretion of PTH, viz. short-term pulses (faster than 2 min), an intermediate pattern of adjusting PTH levels to changed Ca2+ averages, and finally a long-term coupling between PTH and Ca2+ averages after 20 min. Ionized calcium controls the long-term regulation and intermediate adaptation mechanisms, but the short-term fluctuations seem to be due to spontaneous secretion.

Laboratory test of an automated cell analysis system for cervical screening.

An automated cell analysis system (Autoplan-MIAC) for the early detection of precancerous lesions of the cervix was tested under semi-routine conditions in a clinical cytology laboratory. A set of 1500 specimens, highly enriched with abnormal cases, was analysed. Cervical scrapings were collected in suspension and processed by cytocentrifugation for microscopy. Two slides were prepared from each sample: one for staining according to Papanicolaou for the visual reference diagnosis and one for Feulgen staining for automated analysis. The specimens were evaluated in two ways: the first one, which is referred to as the automated machine classification system (AMC), classifies the specimens according to the number and ratio of selected objects (alarms) and is a fully automated system. The second system classifies the specimens after visual evaluation of the stored alarms as they are displayed on a TV monitor, and is designated the interactive machine classification system (IMC). The AMC results showed a false positive rate of 16.5% when the cut-off threshold was selected so that all 117 positively diagnosed specimens were classified 'positive' by the system. In that case 87.4% of the CIN I and 96.9% of the CIN II cases were AMC-positive. The IMC results showed a false positive rate of 2.5%, when 86.3% of the CIN I cases, 96.9% of the CIN II cases and all CIN III and invasive carcinoma cases were positively classified.

Trophoblast tissue culture of human intrauterine and ectopic pregnancies and treatment with methotrexate.

The application of drugs for conservative treatment of patients with ectopic pregnancy has been used worldwide for several years. In-vitro studies, however, are very few. We therefore examined the effects of methotrexate on trophoblast tissue cultures derived from intrauterine and ectopic pregnancies. Methotrexate was administered either 12 h or 6 days after initiation of the culture. Human chorionic gonadotrophin (HCG) levels were measured in the culture medium. All cultures showed secretion of HCG within the first 16 days. Methotrexate concentrations less than 3.8 x 10(-4) mol/l had no effect on HCG secretion. Cultures of ectopic pregnancies required a concentration about 10x higher to induce an equivalent reduction of HCG levels compared to intrauterine pregnancies. A few intrauterine and ectopic pregnancies showed no reduction of HCG values after treatment. These results suggest that data obtained from studies on intrauterine pregnancies may not be transferable to ectopic pregnancies in all instances. In some regimens approximately 8 days are required before the effect becomes measurable. In combination with our clinical data, we therefore recommend not to repeat a methotrexate dose too early in treatment of patients with ectopic pregnancies. The possibility that non-responding patients could exist should be kept in mind.

Influence of time and osmolarity on nuclear area of tumor cells growing in vitro.

We investigated the simultaneous influence of the time of cultivation and of the osmolarity of the medium on nuclear sizes in vitro. Cells from a permanent cell line (MaTu), derived from a human breast cancer, were used. We found a linear increase of nuclear size during the first 64 h in culture. In contrast to the important influence of time on nuclear size in culture, even distinct variations of the osmolarity of the medium had little influence on nuclear size. Only if the osmolarity rose by 28% was there a clear reduction of nuclear size.

Interobserver variability in the cytological diagnosis of 1500 Papanicolaou stained cervical monolayer specimens.

Cervical specimens from 1500 patients were prepared by means of a centrifugation procedure to obtain monolayer specimens suitable for automated screening using a machine. After staining according to Papanicolaou, each specimen was diagnosed by four independent cytologists from two different institutes. Within each institute, noncorresponding screening results were discussed to arrive at a conclusion diagnosis. After discussion of the discrepancies between the two centers, the conclusion diagnoses were combined to one final cytological diagnosis for each specimen. This final diagnosis is to be used as a reference diagnosis to evaluate machine classification as obtained by the AUTOPLAN/MIAC system. This system is presently being tested both in Leiden and in Frankfurt for its accuracy of detecting abnormal lesions in cervical specimens. The used diagnostic procedure resulted in a negative reference diagnosis for 1217 of the 1500 specimens; 170 specimens were diagnosed CIN I or II (mild or moderate dysplasia) and 113 specimens had a positive reference diagnosis (CIN III or invasive carcinoma). Based on these three diagnostic classes, the agreement between the four independent cytologists and the reference diagnosis varied between 93.60% and 96.60%, whereas 95.33% of all 6000 diagnoses correlated with the reference diagnosis.

[The nuclear surface area as a malignancy parameter in breast cancer]. / Die Kernflächengrösse als Malignitätsparameter beim Mammakarzinom.

For better characterisation of the degree of malignancy of breast cancers, we have attempted to establish a correlation between nuclear size and prognosis in breast cancer. Karyometric investigations were carried out on biopsies from 200 primary breast cancers. On the basis of the nuclear areas determined, we were able to distinguish three groups of carcinomas: group I: carcinomas with small nuclear areas (n = 33), mean value 97.76 microns 2, group II: carcinomas with intermediate nuclear areas (n = 98), mean value of the nuclear areas 146.5 microns 2, group III: carcinomas with large nuclear areas (n = 69), mean value 190.8 microns 2. After five years, 6% of the patients in group I had died, as compared to 35% in group II and 48% in group III. The median survival time was 45 to 48 months in group I, as compared to 37 months in group II and 28 months in group III. There was a direct correlation between axillary lymph node status and nuclear size: the carcinomas with the small nuclear sizes showed the least involvement. A comparison of the prognostic relevance of nodal status and nuclear area size, reveals a good relevance for the nuclear area similar to that of the nodal status. The results of the biopsy cytology are already available to the surgeon before the operation.

Long-term follow-up in patients with mammary gland changes found unsuspicious by aspiration cytology.

Between 1971 and 1981, 2,184 female patients with mammary gland changes were examined using the triple diagnosis approach (clinical finding, mammography, aspiration cytology) and were found unsuspicious for cancer. Seven of these patients (0.32%) in a follow-up were found to harbor cancer. In view of these findings it is felt acceptable to postpone immediate surgical intervention in case of negative results of the triple diagnosis approach provided there is a reliable performance of these diagnostic methods and a close follow-up in these patients.

Immunocytochemical staining of different cell types in vaginal smears by monoclonal anti-DNA methylase antibodies.

Enzymatic methylation of mammalian DNA is closely related to the replication process; also, the synthesis of DNA methylase, an enzyme that is responsible for this process, is cell cycle related. A monoclonal antibody against DNA methylase recognizes proliferatively active cells in the heterogeneous population. We used this antibody to identify the proliferative state of different cell types in normal vaginal smears and in smears of patients with precancerous lesions and cervical cancer. In all preparations, the normal epithelial cells remained unstained. The majority of cancer cells gave a positive immunocytochemical signal indicating the presence of DNA methylase antigen and the proliferative state. Staining was also observed in dyskaryotic cells, particularly in nuclei of parabasal-type cells.

Cervical dysplasia: cytology class III D and CIN I-II.

Some aspects of class III D-smears (suggesting slight to moderate dysplasia) have been investigated. Results of a cytological follow-up in 481 patients and of the histological findings immediately or during the follow-up in 142 patients are presented. In 112 patients a triple cervical smear approach has been used to determine the rate of false negative smears and errors of sampling. This approach includes the preparation of three slides with cellular material obtained separately from the anterior cervical lip, the posterior lip and from the endocervical canal, using three cotton applicators. To compare the results of cytology with the grade of CIN in different areas of the conization specimens triple cervical smears have been taken preoperatively. Finally 28 patients with a conization following a class III D-smear have been investigated for HPV-induced cell changes which were found in six cases.

Determining the nuclear area in normal breast epithelia and in the nuclei of mammary carcinomas.

In view of the great variation in the size of epithelial cell nuclei in benign changes in the mammary gland, the cytologist is often faced with diagnostic difficulties. Clear differences in the size of the nuclei in aspiration biopsies from the mammary glands of pregnant women and those from the mammary glands of post-menopausal women seem to indicate that even in normal, unchanged mammary gland epithelia, the cell nuclei size varies in accordance with the hormonal situation and any functional changes that might have occurred. To test these findings, the nuclear area of the mammary gland epithelia was compared in four groups consisting of 20 post-menopausal women, 20 sexually mature women, 20 gravid women and 20 women taking ovulation inhibitors. In addition, we measured the nuclear area of tumour cell nuclei from solidly growing mammary carcinomas and their hybrid forms. The 40 patients with mammary carcinomas included 20 sexually mature women and 20 post-menopausal women. A comparison of the size of the nuclei of normal epithelial cells revealed distinct differences in each group. The only exceptions were the sexually mature women and the women taking ovulation inhibitors, between whom there was no significant difference. The average nuclear area in post-menopausal women was 48 micron 2, in sexually mature women 75 micron 2, in pregnant women 118 micron 2, and in women taking ovulation inhibitors 79 micron 2. The difference between the size of the nuclei in the tumour cells and those in normal mammary gland epithelia was significant in all groups. The average size of the tumour cell nuclei in sexually mature women was 185 micron 2, and in post-menopausal women 170 micron 2. A major difference between the two tumour groups was the noticeably larger range in the size of the nuclear area in the sexually mature women.

Heterochromatic C-bands of chromosome 1 in ovarian cancer patients.

Lymphocyte cultures of 13 patients with ovarian cancer and of seven controls have been used to investigate the C-band lengths of the homologs of chromosome 1. The measurements were performed with the semiautomatic image analysis system Leitz A.S.M. A more than 25% difference in size of the C-bands was more frequent in metaphases of the cancer group (43.8%) than in those of the control group (19.5%). In the cancer group smaller C-bands were found. Especially in the A2-chromosomes the C-bands were smaller than in the same chromosomes of the control group.

In vitro cultivation of xenotransplanted human breast-cancer cells.

Xenotransplanted human breast-cancer tissue growing in the second to the ninth passage in nu/nu mice and normal tissue from nu/nu mice was cultivated in vitro. Thirty-two of fifty-two (62%) cultures grew successfully and have been analyzed. The cells were observed using phase-contrast microscopy and May-Grünwald-Giemsa staining. The following cell types could be distinguished: normal fibroblast-like cells (FC), normal epithelial-like cells (EP I), abnormal epithelial-like cells (EP II), and degenerated or dying cells (DC). After staining, the nuclear area of all cell types was measured. The results were: FC = 280 micrometers 2, EP I = 320 micrometers 2, and EP II = 800 micrometers 2. They were compared with the nuclear area of human breast-cancer cells obtained by aspiration biopsy.