[Arterial occlusion of the eye in infectious endocarditis]

BACKGROUND

Infectious endocarditis can lead to embolic arterial retinal occlusions. Which therapy is indicated?

RESULTS

A 33-year-old man suddenly became blind in his left eye as the result of a central retinal artery occlusion (CRAO). This occurred during high-dosage treatment for infectious endocarditis that had been diagnosed 3 weeks earlier. The echocardiogram showed distinct vegetation and an abscess on the aortic valve. The CRAO together with the ultrasound findings was considered an absolute indication for surgery of the aortic valve. During this emergency operation, a 2 cm deep abscess cavity was found between the mitral and aortic valves. After removal of the abscess, together with the infected valve, a prosthetic valve was inserted. Following the operation, the patient made an uneventful recovery. The antibiotic treatment was continued for several months. The left eye remained sightless. No recurrence of infectious endocarditis occurred during the follow-up of 2 1/4 years. A branch retinal arterial occlusion occurred in the right eye of a 35-year-old man who had suffered from chronic infectious endocarditis for several months. Insufficiency of more than one valve had been diagnosed on several occasions. The patient, a drug-addict, had refused surgical treatment on each occasion. After 3 months, the right eye became completely blind owing to CRAO. Following high-dosage treatment with antibiotics, the infectious endocarditis was healed. The right eye remained blind. One year later the patient died.

CONCLUSION

Retinal arterial occlusion of embolic origin in a patient with infectious endocarditis is an indication for immediate medical and/or surgical treatment. This is of particular importance if there is ultrasound evidence of an abscess in the valve area.

Comparative analysis of prognostic indicators for sarcomas of the soft parts and the viscerae

Purpose of this study was to determine which parameters may be best applied to determine the prognosis of soft tissue and visceral sarcomas, the two groups being regarded as biologically different. In a cohort of 184 soft tissue tumors (STT) and 53 gastrointestinal stromal tumors (GIST), the following factors were examined for their diagnostic and prognostic relevance: patient age, sex, tumor location, histological type, tumor size, tumor grade, DNA ploidy status, mitotic count, and immunohistochemical proliferation index. Tumors were graded according to the FNCLCC system, and antibody Ki-S11 (Ki-67) served as a proliferation marker. Median clinical follow-up time was 48 months. In STT, morphological criteria allowed a ready discrimination between benign and malignant lesions, which was only warranted by histopathological grading in GIST. 178 of all 236 tumors were thus classified as malignant. Whilst most parameters yielded significant results in the univariate analysis, age, sex, and histological type were irrelevant. A proliferation index > 20% predicted a poor outcome in soft tissue sarcomas, in contrast to a threshold of 10% for GIST. In both groups, the Cox multivariate analysis selected the proliferation index as the sole independent predictor of overall survival, whereas it was superseded by the tumor grade with respect to metastatic spread. In conclusion, soft tissue and visceral sarcomas appear to behave basically in a similar manner. Both tumor grade and immunohistochemical proliferation index are of major prognostic value. Concerning the growth fraction, however, different cut-off points should be selected for sarcomas of the soft tissues and those of the digestive tract.

Ki-A10, a germ cell nuclear antigen retained in a subset of germ cell-derived tumors

Monoclonal antibody Ki-A10 recognizes a nuclear antigen of 25 and 22 kd apparent molecular mass, which is abundantly expressed by immature gonocytes, spermatogonia, and spermatocytes, whereas it is absent in spermatids, spermatozoa, oocytes, and normal somatic tissues. In a broad spectrum of human cancers the antibody showed no reactivity except for a small subset of malignant lymphomas. Because of this restricted expression pattern, we examined 173 germ cell tumors and 18 sex cord stromal tumors immunohistochemically to assess the distribution of the Ki-A10 antigen. A strongly positive reaction was found in classic seminomas, dysgerminomas, spermatocytic seminomas, and the germ cell component of gonadoblastomas. Yolk sac tumors presented a heterogeneous reactivity pattern ranging from overall positivity to complete lack of antigen expression, and in three of eight choriocarcinomas, a few clusters of cytotrophoblast cells were strongly labeled. All other tumors, including Leydig and Sertoli cell tumors as well as placental tissue, were negative. Our findings suggest that specific germ cell antigens can be retained in germ cell tumors along particular differentiation pathways. Ki-A10 is the first marker that consistently labels spermatocytic seminoma, further confirming its germ cell origin and suggesting a close relationship to classic seminoma. The antibody may serve for diagnostic purposes and promises new insights into the process of germ cell differentiation and the development of germ cell-derived neoplasia.

Adjuvant immunotherapy in renal cell carcinoma--comparison of interferon alpha treatment with an untreated control

BACKGROUND

Adjuvant immunotherapy of RCC with interferon alpha is still controversial. It was the aim of this study to investigate, whether a selected group of patients with a non-metastatic RCC can profit from this therapy.

MATERIALS AND METHODS

Survival data of 125 patients with a non-metastatic RCC, who underwent a tumor-nephrectomy were analyzed retrospectively, 33 of these patients received an adjuvant immunotherapy with interferon alpha for 1 year. All tumors were classified by the TNM-system. Statistical evaluation was performed by the Kaplan-Meier-Method and the logrank-test.

RESULTS

Tumor stage was seen to be an important prognostic factor in RCC with a significantly better outcome in pT2- as compared to pT3-tumors. Tumor grading was without any prognostic relevance. Adjuvant interferon alpha therapy had no effect on overall survival. After separation of the patients into pT2- and pT3/4-tumors again interferon alpha showed no significant benefit for one of the 2 groups.

CONCLUSIONS

The adjuvant therapy with interferon alpha shows no significant benefit in the treatment of non-metastatic RCC. Tumor stage is no suitable factor to select a group of patients, who might profit from an interferon alpha therapy. Further studies are necessary to isolate better selection factors.

[Otorhinolaryngologic findings in Horton temporal arteritis. Review of the literature and case report]

Otorhinolaryngological findings of a temporal arteritis frequently occur in the beginning and/or course of the disease. A purulent sinusitis can be a sign of recurrence of the arteritis and was diagnosed in a 77-year-old woman with known disease that had been biopsied 6 years earlier. Puncture of the maxillary sinus was considered necessary, but no bacteria were found in purulent sinus discharge. When antibiotic treatment failed to bring about a resolution of the inflammatory condition, steroid therapy was begun and the patient recovered within a few days in response to this treatment. The clinical findings in this case show that early diagnosis and treatment by the otorhinolaryngologist are necessary in order to prevent severe complications of the disease.

Adjuvant interferon alpha therapy in renal cell carcinoma (RCC): prognostic value of DNA cytophotometry

BACKGROUND

Adjuvant immunotherapy with interferon alpha in non-metastatic RCC is still controversial. It was the aim of the present study to investigate whether tumor ploidy can help to isolate a group of patients profitting from this treatment.

MATERIALS AND METHODS

Survival data of 119 patients undergoing tumor nephrectomy because of a non-metastatic RCC were analyzed retrospectively. Ploidy was measured in every tumor by means of DNA-cytophotometry. 24 patients received an adjuvant therapy with interferon alpha for one year. Statistical evaluation was performed by the Kaplan-Meier-Method with the logrank-test.

RESULTS

Ploidy could be measured in all tumors. 56 (47%) tumors showed a diploid, 63 (53%) an aneuploid DNA-distribution. Ploidy was seen to be a good prognostic factor in RCC with significantly better survival in patients with diploid than those with aneuploid tumors. The adjuvant interferon therapy provided a marginal however not significant better survival in diploid tumors. Patients with aneuploid RCC had no benefit from this treatment.

CONCLUSIONS

The data show that an interferon treatment in non-metastatic RCC might improve survival in patients with the prognostic better diploid tumors. However further investigations are necessary to give a general recommendation for this therapy in this group of patients. Additional molecular tumor factors like S-phase analysis and others might also improve patient selection.

Risk assessment of a former military base contaminated with organoarsenic-based warfare agents: uptake of arsenic by terrestrial plants

Organoarsenic-based chemical warfare agents (CWAs) such as the sternutators diphenylchloroarsine (CLARK I), diphenylcyanoarsine (CLARK II) or phenyldichloroarsine (PFIFFIKUS) still pose a notable risk in countries where former military bases that have stored these weapons have not yet been reclaimed. In fact, this is the case for many countries of Eastern Europe and the CIS. One of the most important military bases of the former Third Reich, the Heeresmunitionsanstalt I and II, is situated close to the German-Polish border at Loecknitz (Fig. 1). The German army stored and decanted different compounds of CWAs at this military base until 1945. When the Soviet Army destroyed the base in 1946, large amounts of CWAs and other organoarsenic compounds polluted the soil. Today up to 250 g (!) of arsenic may be found in 1 kg of soil at some places in this area. Since 1991, a Government Working Group has been working on the risk assessment in order to define the scope of reclamation measures. This study investigates the contamination and the uptake of arsenic by plants because little is known about the bioavailability and metabolism of sternutators and their constituents. The total arsenic concentration of nine different species of terrestrial plants with at least six samples per species is presented. In spite of the considerable arsenic contamination of the soil (mean value 923 mg arsenic/kg soil) the plant contamination remained comparably low. The median value of arsenic contamination of the above-ground organs of velvet grass, Holcus lanatus, was 0.7 mg/kg dry wt. and the mean value was 4.3 mg/kg dry wt. due to some highly contaminated samples. The highest arsenic concentration registered was 26 mg/kg dry wt. in a sample of H. lanatus, which was most probably caused by soil particles adhering to the plant. The chemical structure of the arsenic compounds carried by the above-ground plant organs has been determined by gas chromatographic investigations and showed an uptake of triphenyl arsine by the plants.

[Serum concentration of anticonvulsants. Practical guidelines for measuring and useful interpretation. Therapy Committee of the German Section of the International Epilepsy League]

The clinical relevance of being informed on the serum concentration of antiepileptic drugs has been judged very differently during the last decades. Therefore the Commission on the treatment of epilepsy (German section of the International League against Epilepsy) had the task to outline the importance of therapeutic monitoring of anticonvulsant serum concentrations. The possibility of determining the serum concentration of anticonvulsants induced the elaboration of "therapeutic drug level ranges". The usefulness of determining serum concentrations of antiepileptic drugs in clinical management of patients with epilepsy depends decisively on the following questions: Can the efficacy of antiepileptic drug treatment be increased by serum concentration monitoring? Can the rate of adverse effects of antiepileptic drugs be reduced by serum concentration monitoring? Clinical experience suggests numerous indications of therapeutic drug monitoring, scientific studies however, supporting these empirical guidelines are not available. Therefore, therapeutic drug monitoring may be restricted for some special situations which have to be justified in every single case. Tailored determinations with specific purposes are e.g.: resistance to therapy, including suspected irregular intake; suspected intoxication, particularly during combined therapy; the possibility of significant changes in the dosage-serum concentration relationship (interactions with other drugs, unusual pharmacokinetics in childhood, in pregnancy etc.).

Combination therapy with tacrolimus and mycophenolate mofetil following cardiac transplantation: importance of mycophenolic acid therapeutic drug monitoring

BACKGROUND

Interest has recently been expressed in tacrolimus and mycophenolate mofetil (MMF), two potent immunosuppressants, for a variety of transplant indications. The efficacy of this combination was assessed as primary therapy following cardiac transplantation.

METHODS

Forty-five patients were enrolled; 15 into Phase I and 30 to Phase II of the study. Intravenous tacrolimus was administered for 2-3 days to all patients prior to conversion to oral therapy; target blood concentrations were 10-15 ng/mL. Treatment also consisted of steroids and MMF. During Phase I, a fixed 2 g/day dose of MMF was given whilst doses were adjusted according to mycophenolic acid (MPA) plasma levels during Phase II (target range 2.5-4.5 microg/mL). Mean follow-up was 696 +/- 62 days and 436 +/- 88 days for Phases I and II, respectively.

RESULTS

Phase I: Patient survival was 100%. Rejection was diagnosed in 66.7% of patients (mean number of episodes per patient 1.33 +/- 1.18). Retrospective analyses indicated that whereas mean MPA plasma levels >3.0 microg/mL were not associated with rejection, no correlation was found with tacrolimus blood concentrations. Phase II: A survival rate of 96.7% was evident, one patient having died from aspergillosis. Diagnoses of rejection were made in 10.0% of patients (0.10 +/- 0.31 episodes per patient) and confounding factors were present in all 3 cases. MPA trough levels were 1.0 +/- 0.3 microg/mL at this time. Resolution was apparent following pulse steroid therapy. Steroids were successfully withdrawn from all patients who completed 6 months' treatment.

CONCLUSIONS

Combination therapy with tacrolimus and MMF is associated with suppression of acute myocardial rejection; however, this is dependent upon routine therapeutic drug monitoring.

Elevated tryptase, nerve growth factor, neurotrophin-3 and glial cell line-derived neurotrophic factor levels in the urine of interstitial cystitis and bladder cancer patients

PURPOSE

The 2 prominent features of interstitial cystitis are pain and increased numbers of mast cells in the bladder. In this pilot study we determined the concentration of soluble mediators associated with activation of sensory neurons and/or mast cells that were present in the urine.

MATERIALS AND METHODS

The study groups included 4 interstitial cystitis patients, 7 kidney donors with no history of bladder disease as negative controls, 6 bladder cancer patients and 7 patients with urinary tract infection as reference controls. Urine samples were assayed for different soluble mediators using immunoassays for tryptase (a marker for mast cell activation), neurotrophic factors (markers of neuronal plasticity) and chemokines (markers of inflammatory cell activity). Results were normalized based on creatinine concentration.

RESULTS

There was a marked increase in the average amounts of tryptase and 3 neurotrophic factors in patient urine. Interestingly, the mediator profile in the urine of bladder cancer patients was indistinguishable from that of interstitial cystitis patients with respect to these same 4 proteins. There was no difference between normal control and urinary tract infection urine samples.

CONCLUSIONS

These findings may account for several clinical and pathological features found in interstitial cystitis and bladder cancer. Although preliminary due to the limited numbers of patients, they also suggest that increased levels of neurotrophin-3, nerve growth factor, glial cell line-derived neurotrophic factor and tryptase in the urine could serve as a basis for adjunct diagnosis, monitoring and treatment of interstitial cystitis.

Episodic retrieval activates the precuneus irrespective of the imagery content of word pair associates. A PET study

The aim of this study was to evaluate further the role of the precuneus in episodic memory retrieval. The specific hypothesis addressed was that the precuneus is involved in episodic memory retrieval irrespective of the imagery content. Two groups of six right-handed normal male volunteers took part in the study. Each subject underwent six [15O]butanol-PET scans. In each of the six trials, the memory task began with the injection of a bolus of 1500 MBq of [15O]butanol. For Group 1, 12 word pair associates were presented visually, for Group 2 auditorily. The subjects of each group had to learn and retrieve two sets of 12 word pairs each. One set consisted of highly imaginable words and another one of abstract words. Words of both sets were not related semantically, representing 'hard' associations. The presentations of nonsense words served as reference conditions. We demonstrate that the precuneus shows consistent activation during episodic memory retrieval. Precuneus activation occurred in visual and auditory presentation modalities and for both highly imaginable and abstract words. The present study therefore provides further evidence that the precuneus has a specific function in episodic memory retrieval as a multimodal association area.

[Antibiotic prophylaxis in hip joint surgery]

Nosocomial deep wound infections are serious complications after hip joint surgery. Our aim was to determine whether there is a difference in rates of nosocomial infections between group of patients after elective surgery of hip replacement and group of patients with hip replacement after trauma. Both groups of patients had perioperative prophylaxis with amoxycillin. We found that the overall trauma patients infection rate was 0.9 per cent compared with 1.5 per cent for elective surgery infections. In both groups of patients a postsurgery stress was documented according to increase of acute phase proteins (C-reactive protein, orosomucoid and fibrinogen) in plasma for a minimum 10 days after surgery. We conclude, that both groups of patients had benefit from amoxycillin prophylaxis therapy.

Directly measured kinetics of circulating T lymphocytes in normal and HIV-1-infected humans

The dynamic basis for T-cell depletion in late-stage HIV-1 disease remains controversial. Using a new, non-radioactive, endogenous labeling technique, we report direct measurements of circulating T-cell kinetics in normal and in HIV-1-infected humans. In healthy, HIV-1-seronegative subjects, CD4+ and CD8+ T cells had half-lives of 87 days and 77 days, respectively, with absolute production rates of 10 CD4+ T cells/microl per day and 6 CD8+ T cells/microl per day. In untreated HIV-1-infected subjects (with a mean CD4 level of 342 cells/microl), the half-life of each subpopulation was less than 1/3 as long as those of healthy, HIV-1-seronegative subjects but was not compensated by an increased absolute production rate of CD4+ T cells. After viral replication was suppressed by highly active antiretroviral therapy for 12 weeks, the production rates of circulating CD4+ and CD8+ T cells were considerably elevated; the kinetic basis of increased CD4 levels was greater production, not a longer half-life, of circulating cells. These direct measurements indicate that CD4+ T-cell lymphopenia is due to both a shortened survival time and a failure to increase the production of circulating CD4+ T cells. Our results focus attention on T-cell production systems in the pathogenesis of HIV-1 disease and the response to antiretroviral therapy.

[Direct and indirect costs of schizophrenia]

In the present study the costs of schizophrenia in Germany were studied using the "bottom up" prevalence-based method. In a random sample of 180 schizophrenic patients stratified according to the most important care institutions, direct and indirect costs were retrospectively documented for a 12-month period. Depending on the place of recruitment and the extent of care provided, total yearly costs result between about DM 33,000 for a patient treated predominantly on an outpatient basis and about DM 126,000 for a patient requiring hospital care and about DM 135,000 for a patient in job rehabilitation. The direct yearly treatment costs were, as expected, lowest for patients recruited in the private practice of a psychiatrist and predominantly treated on an outpatient basis (DM 5,788), and were the highest in the psychiatric hospital (DM 64,661) and in job rehabilitation (DM 79,996). In the patients recruited in the outpatient domain, doctors' fees and medication together were responsible for only 4.5% of the total costs, whereas the indirect costs (e.g., through work incapacity) were responsible for 87% of the total yearly costs. For methodological reasons the total costs caused by schizophrenic psychoses in Germany per year can at present be estimated only roughly. A conservative estimate is between 8.5 and 18 billion DM per year. The study shows that schizophrenia is a very expensive illness, the direct and indirect costs of which are on the whole comparable to those of the common somatic illnesses. Therefore, also for economical reasons, sufficient financial means should be invested in the research and treatment of this severe illness.

[O-15-butanol Pet activation study on the cerebral representation of declarative memory]

AIM

In this study, neuroanatomical correlates of encoding and retrieval in paired associate learning were evaluated with positron emission tomography using auditorily presented highly imaginable words.

METHODS

Six right-handed normal male volunteers took part in the study. Each subject underwent six O-15-butanol PET scans. On each of the six trials the memory task began with the injection of a bolus of O-15-butanol. The subjects had to learn and retrieve twelve word pairs (highly imaginable words, not semantically related). The presentation of nonsense words served as reference condition.

RESULTS

Recall accuracy after 2-4 presentations was high during the PET measurement. In both encoding and retrieval we found anterior cingulate activation. We show bilateral dorsolateral prefrontal activation during the encoding of auditorily presented word pair associates, whereas retrieval led to left frontal activation. Furthermore, we demonstrate the importance of the precuneus in the retrieval of highly imaginable word-pair associates.

CONCLUSION

Our results support the hypothesis of the presence of distributed widespread brain structures subserving episodic declarative memory.

Encoding and retrieval in declarative learning: a positron emission tomography study

We present neuroanatomical correlates of encoding and retrieval in an episodic memory task using visually presented highly imaginable word-pair associates. A total of 13 right-handed normal male volunteers took part in the study. Each subject underwent six (15)O-butanol PET scans. On each of the six trials the memory task began 30 s before the injection of a bolus of (15)O-butanol. The subjects had to learn and retrieve 12 word pairs (highly imaginable words, not semantically related, hard associations). The presentation of nonsense words served as a reference condition. Recall accuracy after 2-4 presentations was 66.1%+/-21.1 correct during the PET measurement so that scanning during the retrieval of word pair associates was appropriate to capture the brain activity associated with retrieval. The results obtained support the hypothesis of the presence of an asymmetric network consisting of distributed brain structures subserving associative memory. We show left dorsolateral prefrontal activation during the encoding of visually presented word pair associates, whereas retrieval led to bilateral frontal activation. Furthermore, the importance of the precuneus in the retrieval of highly imaginable word-pair associates using visual imagery as a mnemonic strategy is demonstrated.

Correlation between mitotic and Ki-67 labeling indices in paraffin-embedded carcinoma specimens

The mitotic index (MI) and the Ki-67 labeling index (LI) are both understood to measure cellular proliferation, but their relationship is poorly defined. We determined the mitotic index in hematoxylin and eosin-stained paraffin sections of 189 consecutive carcinomas and performed immunohistochemistry on sections from the corresponding blocks using the Ki-67-specific monoclonal antibody Ki-S5. The distributions of MI and LI in the entire series were clearly different, the former fitting a Poisson function in contrast to a broad-tailed unspecific distribution of the latter. Both indices were closely correlated in mammary carcinomas and non-small cell lung cancers, and to a slightly lesser extent in colorectal adenocarcinomas. No significant association was found in small cell lung cancers. In squamous cell carcinomas, the two parameters were inversely correlated. A good agreement between MI and LI values was observed in well-differentiated and moderately well-differentiated cancers regardless of their histological type, whereas in poorly differentiated carcinomas the correlation was not significant. We conclude that MI and LI measure different proliferation characteristics. Their relationship appears to depend on the tumor type and the degree of differentiation. Rather than artifacts due to processing or evaluation techniques, specific differences in cell cycle kinetics are likely to account for these discrepancies.

[Recommendations for blood studies and clinical monitoring in early detection of valproate-associated liver failure. Results of a consensus conferences 9 May - 11 May 1997 in Berlin]

Valproate is a frequently used antiepileptic drug. It is associated with rare but serious adverse effects like liver failure. The first symptom is impairment of the patient's well being. Isolated changes of standard laboratory liver parameters are not reliable early indicators. Thus, according to the knowledge of today, prophylactic blood screening cannot predict complications. On the contrary, clinical symptoms are the most relevant indicators of impending complications, eventually supported by laboratory findings. An abrupt withdrawal of valproate and administering carnitin in parallel can interrupt the otherwise fatal course of the complication and induce a subsequent recovery. At a Consensus Conference the current knowledge about early detection and therapy of the valproate-induced serious hepatotoxicity was discussed. The results regarding recommended laboratory screening, as well as diagnostic and therapeutic strategies are reported.

Prenatal stress alters brain biogenic amine levels in primates

In this study, we assessed behavioral responses to social separation at 8 months of age and cerebrospinal fluid (CSF) concentrations of biogenic amines and metabolites at 8 and 18 months of age in 12 rhesus monkeys derived from either stressed or undisturbed pregnancies. Compared to controls from undisturbed pregnancies, prenatal stress-derived monkeys had higher concentrations of 3-methoxy-4-hydroxyphenylglycol (MHPG), and 3,4-dihydroxyphenylacetic acid in CSF than controls. Norepinephrine and MHPG response to stress were both correlated between 8 and 18 months of age. There were few group differences in behavior during social separation; however, several behavioral differences between groups were found when monkeys were reunited with cage mates. Prenatally stressed monkeys spent more time clinging to their surrogates and exploring (including eating and drinking), while controls showed more locomotion and social play with their cage mates. Collectively, our findings suggest that chronic unpredictable psychological stress during pregnancy has long-lasting effects on noradrenergic and dopaminergic activity and behavior in the offspring of gestationally stressed primate mothers.

Quantitative assessment of surgically induced mitral regurgitation using radionuclide ventriculography and first pass radionuclide angiography

Radionuclide ventriculography has been used in humans to evaluate valvular incompetency. The stroke volume ratio, derived from the radionuclide ventriculogram, is used to quantify the severity of mitral regurgitation (MR). Previous studies conducted in humans have shown that left to right stroke volume ratio increases as the severity of MR increases. In this study, we evaluated radionuclide ventriculography as a noninvasive method to detect MR in dogs with surgically created mitral insufficiency. Six male and three female adult, conditioned mongrel dogs were used. Scintigraphic studies were performed prior to and 4 weeks after surgically created MR. Because of the overlap of the left and right ventricles when viewed from a left lateral position, we combined data from a first-pass radionuclide angiocardiogram with the radionuclide ventriculogram to obtain a corrected stroke volume ratio. Blood flow transit parameters were also derived from the first-pass radionuclide angiocardiogram. Standard left ventricular functional indices were also measured from the radionuclide ventriculogram. On the left lateral view of the heart, 25 to 30% of the right ventricular volume overlaps the left ventricle. After correcting for the overlap, the stroke volume ratio of normal dogs was 1.17+/-0.178 (mean+/-SD), which increased to 2.06+/-0.41 (mean+/-SD) (p < .001) 4 weeks after creation of MR. The was no significant change in left ventricular ejection fraction or peak rate of ejection following MR. The transit times of blood through the left ventricle were measured from the first-pass radionuclide angiocardiogram and were expressed as half-time clearance, peak clearance rate, and time to peak clearance rate. The baseline half-time clearance was 2.07+/-0.71 s (mean+/-SD), which increased to 6.70+/-4.89 s (mean+/-SD) (p = .02) after creation of MR. The baseline peak clearance rate was 49.75+/-8.96 cts/s (mean+/-SD), which decreased to 23.12+/-6.84 cts/s (mean+/-SD) (p < .001) after creation of MR. Stroke volume ratios significantly increased following creation of MR. Blood flow transit through the left ventricle slowed following creation of MR. The variability of these parameters were small in the baseline studies, suggesting these techniques may be clinically useful to gauge the severity of MR in dogs.

Preclinical review of cerivastatin sodium--a step forward in HMG-CoA reductase inhibition

Epidemiological studies have established that elevated concentrations of plasma cholesterol, particularly the low density lipoprotein (LDL) cholesterol, is one of the major risk factors for the development of arteriosclerosis and ischemic heart disease. Treatment with HMG-CoA reductase inhibitors (vastatins) has become the most successful drug treatment in lowering total plasma and LDL cholesterol concentrations in the last years. The vastatins already available for treatment are therapeutically used in a dose-range between 10 and 80 mg/day. The new enantiomerically pure pyridine derivative cerivastatin sodium has demonstrated its efficacy in significantly lower doses in the microgram-range, not only in preclinical but also in clinical studies with daily doses of only 0.1-0.3 mg. The differences in the therapeutic doses are reflected by the Ki- and IC50-values from enzyme inhibition tests in comparison with various HMG-CoA reductase inhibitors. Cerivastatin sodium exhibits much higher enzyme affinity with factors between 70 and almost 200. The Ki-value for cerivastatin sodium was 1.3 x 10(-9) M in comparison to 150 x 10(-9) M for lovastatin. The extremely high enzyme affinity of cerivastatin sodium was also reflected in its high activity in vivo. In acute in vivo studies cerivastatin sodium inhibited the hepatic [14C]cholesterol synthesis from [14C]acetate in both rats and dogs by 50% after oral administration at doses of 0.002 mg/kg body weight (ED50-values). This dose was comparable to 0.3 mg/kg of lovastatin. In subchronic dog studies a dose of 0.03 mg/kg lowered the serum LDL cholesterol concentration by 35% which is comparable with doses of 8-10 mg lovastatin/kg. Interesting results were observed in cholestyramine-primed dogs when 0.1 mg cerivastatin sodium/kg p.o. markedly decreased the serum triglycerides up to 70%. Cerivastatin shows a favourable pharmacokinetic profile with high liver selectivity. Rat studies have shown almost complete absorption and rapid hepatic clearance. Cerivastatin was highly bound to plasma proteins of rats, dogs and humans (>98%). Cerivastatin metabolites were excreted mainly via feces. The metabolism of cerivastatin sodium in man follows two metabolic pathways, demethylation to metabolite M1 and stereospecific hydroxylation to M23. The three major metabolites M1, M23 and the hydroxylated and demethylated metabolite M24 are highly active inhibitors not only in vitro but also in vivo. The human specific metabolites M23 and M24 inhibited the HMG-CoA reductase isolated from rat liver with the same potency as the parent compound cerivastatin sodium (IC50: 1.0-1.2 x 10(-9) M). M1 was slightly less active. Corresponding pharmacological activity was observed in vivo. M23 and M24 inhibited [14C]cholesterol synthesis from [14C]acetate in rat liver with ED50)-values between 0.001 and 0.002 mg/kg body weight which is similar to cerivastatin sodium and M1 exhibited an ED50-value of <0.006 mg/kg The strong inhibitory activity of these metabolites, in addition to cerivastatin's high enzyme affinity may explain the extraordinary pharmacological activity of cerivastatin and its ultra-low dose in man and demonstrates cerivastatin to be the most active HMG-CoA reductase inhibitor amongst all vastatins.