Human metabolism of the proteasome inhibitor bortezomib: identification of circulating metabolites.

Bortezomib [N-(2,3-pyrazine)carbonyl-L-phenylalanine-L-leucine boronic acid] is a potent first-in-class dipeptidyl boronic acid proteasome inhibitor that was approved in May 2003 in the United States for the treatment of patients with relapsed multiple myeloma where the disease is refractory to conventional lines of therapy. Bortezomib binds the proteasome via the boronic acid moiety, and therefore, the presence of this moiety is necessary to achieve proteasome inhibition. Metabolites in plasma obtained from patients receiving a single intravenous dose of bortezomib were identified and characterized by liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). Metabolite standards that were synthesized and characterized by LC/MS/MS and high field nuclear magnetic resonance spectroscopy (NMR) were used to confirm metabolite structures. The principal biotransformation pathway observed was oxidative deboronation, most notably to a pair of diastereomeric carbinolamide metabolites. Further metabolism of the leucine and phenylalanine moieties produced tertiary hydroxylated metabolites and a metabolite hydroxylated at the benzylic position, respectively. Conversion of the carbinolamides to the corresponding amide and carboxylic acid was also observed. Human liver microsomes adequately modeled the in vivo metabolism of bortezomib, as the principal circulating metabolites were observed in vitro. Using cDNA-expressed cytochrome P450 isoenzymes, it was determined that several isoforms contributed to the metabolism of bortezomib, including CYP3A4, CYP2C19, CYP1A2, CYP2D6, and CYP2C9. The development of bortezomib has provided an opportunity to describe the metabolism of a novel boronic acid pharmacophore.     

Differential modulation of auditory thalamocortical and intracortical synaptic transmission by cholinergic agonist

To investigate synaptic mechanisms underlying information processing in auditory cortex, we examined cholinergic modulation of synaptic transmission in a novel slice preparation containing thalamocortical and intracortical inputs to mouse auditory cortex. Extracellular and intracellular recordings were made in cortical layer IV while alternately stimulating thalamocortical afferents (via medial geniculate or downstream subcortical stimulation) and intracortical afferents. Either subcortical or intracortical stimulation elicited a fast, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)-sensitive, monosynaptic EPSP followed by long-duration, polysynaptic activity. The cholinergic agonist carbachol suppressed each of the synaptic potentials to different degrees. At low concentrations (5 μM) carbachol strongly reduced (>60%) the polysynaptic slow potentials for both pathways but did not affect the monosynaptic fast potentials. At higher doses (10–50 μM), carbachol also reduced the fast potentials, but reduced the intracortically-elicited fast potential significantly more than the thalamocortically-elicited fast potential, which at times was actually enhanced. Atropine (0.5 μM) blocked the effects of carbachol, indicating muscarinic receptor involvement. We conclude that muscarinic modulation can strongly suppress intracortical synaptic activity while exerting less suppression, or actually enhancing, thalamocortical inputs. Such differential actions imply that auditory information processing may favor sensory information relayed through the thalamus over ongoing cortical activity during periods of increased acetylcholine (ACh) release.     

Preservation of the thin distal urethra in hypospadias repair

PURPOSE: We report our experience with preserving the thin distal urethra lacking corpus spongiosum for the treatment of hypospadias. MATERIALS AND METHODS: From January 1997 to October 1999 we treated primary hypospadias in 77 boys with a mean age of 4 years 10 months. After degloving the penile skin a segment of thin distal urethra lacking corpus spongiosum was noted in 18 patients (23.4%) with a mean age of 3 years 5 months. The thin distal urethra was preserved and incorporated as part of urethroplasty (group 1). The procedure was primarily completed by tubularized incised plate urethroplasty. We also performed tubularized incised plate urethroplasty in 31 boys (40.3%) with a mean age of 5 years 2 months who had normal coverage of the corpus spongiosum of a hypospadiac urethra (group 2). We compared the results of treatment in these 2 groups. The remaining 28 patients (36.4%) treated with other methods were excluded from study. RESULTS: In group 1 the distance from the original meatus to the urethra covered by healthy corpus spongiosum was 4 to 20 mm. (mean 8.2). If the thin distal urethra had been excised, the urethral meatus would have been relocated more proximal in these boys. Mean followup in groups 1 and 2 was 9.9 and 7.6 months, respectively. Postoperatively there were 2 (11.1%) urethrocutaneous fistulas in group 1 and 4 (12.9%) in group 2. Tubularized incised plate repair was successful in all 10 cases (100%) of distal hypospadias in group 2, and in 15 of 18 (83.3%) and 17 of 21 (81%) of proximal hypospadias cases in groups 1 and 2, respectively. There was no statistically significant difference in the success rate of hypospadias repair in the groups. CONCLUSIONS: We noted a significantly thin distal urethra in 23.4% of our cases of primary hypospadias. Mean length of the thin distal urethra was 8.2 mm. Preserving the thin distal urethra may simplify the operative procedure without compromising the surgical results of tubularized incised plate urethroplasty.     

Initial 10-year experience of sperm cryopreservation services for cancer patients.

Offering sperm cryopreservation to preserve the fertility of male cancer patients is a relatively recent service in Asia. This study analyzed the types of cancer, timing of collection, sperm quality, and utilization for reproductive services by patients during a 10-year period at a medical center in Taiwan. A total of 75 oncology patients elected to freeze sperm for fertility preservation at our medical center during the initial 10 years of the availability of this service. The mean age of the patients was 25.7 years. Storage was discontinued in 13 (17%) patients and their survival duration was 13.1 +/- 11.1 months. The utilization rate of sperm cryopreservation was 2.8% (75/2642). The types of cancer varied, with leukemia (35%), lymphoma (25%), and testicular cancer (13%) comprising the largest groups. A significantly lower sperm count was found in patients with chronic myelogenous leukemia, suggesting the need for earlier sperm collection after initiation of cancer treatment. Only three (4%) patients utilized their specimens for reproductive purposes. There was no clinical pregnancy during the study period, although one biochemical pregnancy was achieved. The low rates of sperm cryostorage for fertility preservation in cancer patients in this study suggest that there is a need for greater emphasis of this option for male oncology patients whose fertility is likely to be affected by chemotherapeutic treatment.     

Late-onset and rare far-advanced pulmonary involvement in patients with sarcoidosis in Taiwan.

BACKGROUND: Sarcoidosis is still considered a rare multisystem disorder in Taiwan, and data on the disease course and outcome are limited. We analyzed the clinical manifestations, disease course and complications in Taiwanese patients with sarcoidosis. METHODS: A retrospective cohort design was used. Fifty-six patients with sarcoidosis diagnosed between 1985 and 2004 were included. Their clinical features, laboratory findings at initial presentation, disease course, and complications were analyzed. RESULTS: Forty-three patients (76.8%) were female. The mean age at symptom onset was 47 years. The most common clinical symptoms were pulmonary (82.1%), cutaneous (23.2%), ophthalmic (19.6%), and articular (17.8%). Only two patients presented with L?fgren's syndrome. There was a seasonal variation in disease onset, with higher incidence in winter and early spring. No advanced pulmonary involvement was noted. Elevated levels of serum angiotensin converting enzyme (sACE) were found in 72.5% (29/40) of patients with active sarcoidosis, and significantly higher levels of sACE were found in patients with lung involvement (27.98+/-1.71 IU/L vs. 18.2+/-2.76 IU/L; p<0.01). In 50% (20/40) of patients, sACE levels declined significantly in parallel with clinical remission (24.75+/-1.53 IU/L vs. 16.33+/-1.21 IU/L; p<0.05). Spontaneous complete remission was found in 20.7% of patients, whereas 39.6% of patients with multiple extrapulmonary involvement responded poorly to intensive corticosteroids plus various immunosuppressants. CONCLUSION: In this series, the mean age of disease onset was in middle age (mean, 47 years old), there was a low incidence of L?fgren's syndrome (3.6%), and no patients had advanced pulmonary syndrome. The results of this study also suggest that sACE might be a marker of pulmonary involvement that is also useful in monitoring disease activity.     

Spinal pseudoarthrosis: a rare complication in psoriatic arthritis.

Discovertebral erosion with pseudoarthrosis is a well-known complication in ankylosing spondylitis but it is seldom mentioned in psoriatic arthritis. We report a 53-year-old woman with an 8-year history of psoriatic arthritis who developed severe low back pain followed by sudden onset of numbness in the lower limbs, weakness and dysesthesia. Abnormal contour of L1 and L2 vertebrae and intervertebral disc space was noted during radiologic examination. Pseudoarthrosis was suspected based on extensive osseous resorption and reactive sclerosis about the discovertebral junction on magnetic resonance imaging study. She underwent emergency operation due to spinal instability with neurologic deficit. Pseudoarthrosis was confirmed intraoperatively. No evidence of infection or neoplasms was found. This case shows that pseudoarthrosis can be complicated in patients with psoriatic arthritis, and this possibility should be considered in patients with previously quiescent disease.     

Penile tuberculosis associated with monoclonal gammopathy of undetermined significance.

Mycobacterium tuberculosis (TB) infection of the penis is a rare but serious problem. We report a case of penile TB in a 75-year-old man who presented with fever and dyspnea. No active lung lesions except pleural and pericardial effusion were found on chest X-ray. Monoclonal gammopathy of undetermined significance was diagnosed after serum and urine electrophoresis studies, and repeated bone marrow studies. Genital examination showed diffuse papulonecrotic skin ulcers involving the whole penile shaft, extending ventrally to the median raphe of the scrotum. Pus smear showed positive acid-fast stain, and culture yielded M. tuberculosis. Culture of pleural and pericardial effusion was also positive for M. tuberculosis. Anti-TB treatment was given with isoniazid, ethambutol, rifampin and pyrazinamide, and the cutaneous lesion was noted to be healed at follow-up 6 months later. Although rare, the possibility of TB as a cause of genital ulcer should be kept in mind.     

Approval summary: azacitidine for treatment of myelodysplastic syndrome subtypes.

PURPOSE: This article summarizes data submitted to the U.S. Food and Drug Administration for marketing approval of azacitidine as injectable suspension (Vidaza, Pharmion Corporation, Boulder, CO) for treatment of patients with myelodysplastic syndrome. EXPERIMENTAL DESIGN: In one phase 3 controlled trial, 191 study subjects were randomized to treatment with azacitidine or to observation; an additional 120 patients were treated with azacitidine in two phase 2 single arm studies. The primary efficacy end point was the overall response rate, defined as complete or partial normalization of peripheral blood counts and bone marrow blast percentages for at least 4 weeks. RESULTS: In the controlled trial, the overall response rate was 15.7% in the azacitidine treatment group; there were no responders in the observation group (P < 0.0001). Response rates were similar in the two single arm studies. During response patients stopped being red cell or platelet transfusion dependent. Median duration of responses was at least 9 months. An additional 19% of azacitidine-treated patients had less than partial responses, most becoming transfusion independent. The most common adverse events attributed to azacitidine were gastrointestinal, hematologic, local (injection site), and constitutional. There were no azacitidine-related deaths. CONCLUSIONS: On May 19, 2004 the U.S. Food and Drug Administration approved azacitidine as injectable suspension for treatment of patients with the following myelodysplastic syndrome subtypes: refractory anemia or refractory anemia with ringed sideroblasts (if accompanied by neutropenia or thrombocytopenia or requiring transfusions), refractory anemia with excess blasts, refractory anemia with excess blasts in transformation, and chronic myelomonocytic leukemia. Full prescribing information is available at http://www.fda.gov/cder/foi/label/2004/050794lbl.pdf. Azacitidine is the first agent approved for treatment of myelodysplastic syndrome.