Cross-species drug metabolism and impact of metabolic stability testing under anaerobic condition on predicting pharmacokinetics of keto-enol containing compound in humans

After oral administration of [14C]-S-1360 in rats and dogs, [14C]-S-1360 was absorbed rapidly and the bioavailability was 93.7% in rats and 75.1% in dogs. Based on the results in animals, good systemic exposure would be expected in humans. In contrast to the expectation, the exposure was low in healthy volunteers compared to the exposure expected. In addition, human mass balance study using [14C]-S1360 revealed that a large amount of metabolites existed in human plasma. The major metabolites in human plasma were reduced metabolite (HP1) and S-1360 N-glucuronide, and they respectively accounted for approximately 30% of total AUC. Unchanged S-1360 accounted for only 14% of total AUC. The results showed that a significant difference between humans and animals were observed in metabolism of S-1360. Although S-1360 was stable in human hepatocytes under aerobic condition (approximately 84% remaining at 1 h), S-1360 was labile under anaerobic condition (approximately 55% remaining at 1 h). The present study revealed that the reductive metabolism pathways are the key metabolic pathway of S-1360, especially the metabolic stability test under anaerobic condition is important to predict pharmacokinetics of keto-enol containing compound, such as S-1360.

The development of polyanhydrides for drug delivery applications

This paper reviews the development of the polyanhydrides as bioerodible polymers for drug delivery applications. The topics include design and synthesis of the polymer, physical properties, techniques to fabricate the polymer into drug delivery devices, evaluation of biocompatibility, and example applications of the polyanhydrides. Discussion of the interrelationship between the physical-chemical properties of the polyanhydrides, fabrication methods, and drug release rates is included. One section is devoted to a case study to provide a historical perspective of the development a polyanhydride-based drug delivery treatment from the conception of the idea to the final stages of human clinical trials. This section includes an outline of the extensive in vitro and in vivo testing that is necessary for development of a new material for biomedical applications.

A new generic column switching system for quantitation in cassette dosing using LC/MS/MS

Cassette dosing is a method in which multiple drugs are administered to a single animal at the same time, and the plasma concentrations of the individual compounds are simultaneously determined. This method enables high-throughput rapid screening for pharmacokinetic assessment of new drug candidates. An available gradient method was modified for cassette dosing analysis to attain the advantages of high sensitivity and applicability to a wide range of compounds. However, two problems arose; (1). the time-consuming optimization of mobile phases for each compound group, which limited applicability and (2). the remarkable suppression of ionization by polyethyleneglycol, which is commonly used in intravenous administration. To resolve these problems, a new column switching method was established to attain wider applicability and avoid the ionization suppression. This column switching system is very simple because the trap column and the analytical column are specified and the mobile phase is selected from only two species. Method optimization requires only the selection of the mobile phase and takes only a few hours. About 200 compounds, which were administered as about 50 cassettes, were analyzed using this column switching system. Assay validation of one cassette was carried out, and good accuracy and precision were obtained. About 90% of the compounds could be determined within 20% bias. These results showed that this new column switching system for cassette dosing is accurate enough for the screening of drug candidates and offers wide applicability for various compounds. This system was shown to be very useful for the determination of cassette dosing samples, containing multiple compounds.

Endobronchial metastasis from prostate cancer

We describe a case of endobronchial metastasis from prostate cancer originally diagnosed as primary bronchogenic carcinoma. We conducted a sleeve lobectomy and determined a final diagnosis using a serumprostate-specific antigen and immunohistochemical studies.

Undifferentiated tumor originating in the cerebral dysgenetic lesion resembling fibrous cartilage: case report

A 33-year-old woman had an undifferentiated tumor originating in the cerebral dysgenetic lesion resembling fibrous cartilage. She had a headache, vomiting, late-onset epilepsy and left hemiparesis. The lesion was located in the right temporal lobe on computed tomographic (CT) scan. It was totally resected and only local irradiation was performed postoperatively. Normal cortical architectures were lost in the resected specimens. Straight or curved fasciculi composed of fine collagen fibers were distributed in parallel and perpendicular to the cortical surface in the mildly eosinophilic hyaline matrix. Hypertrophic astrocytes were scattered with low cellularity in these abnormal cortices. Clusters of tumor cells were observed in a few areas. The tumor cells, having oval and relatively vesicular nuclei with a few prominent nucleoli and basophilic well-circumscribed narrow cytoplasm, had proliferated diffusely with a cobblestone appearance. Immunohistochemical and electron microscopic investigations demonstrated no evidence of specific differentiation, either. There were 14.5 mitotic figures/high power field on average and most nuclei of the tumor cells were strongly positive for proliferating cell nuclear antigen (PCNA). Moreover, subarachnoid dissemination of the tumor cells were apparent in a few areas. Nevertheless the patient returned to work and no recurrence was observed for 10 years postoperatively. We concluded that neoplastic transformation occurred de novo in the dysgenetic cortex.

Reverse iontophoresis: noninvasive glucose monitoring in vivo in humans

PURPOSE

To demonstrate that "reverse iontophoresis" can be used to noninvasively obtain information about systemic glucose levels in vivo in humans.

METHODS

The passage of current across the skin in vivo drives ions into the tissue, from the electrode chambers positioned on the skin surface, and simultaneously pulls ions from the body in the opposite direction. Because of the net negative charge on the skin, under normal conditions, the membrane is permselective to cations, and a potential gradient also results, therefore, in electroosmotic convection of solvent in the direction of counterion flow (i.e., from anode to cathode). Thus, it is also possible to enhance the transport of polar, yet uncharged, species using iontophoresis. In an earlier study, the in vitro extraction of glucose, by "reverse iontophoresis" was established, and extension of the approach to an in vivo model was indicated. The idea has therefore been further explored in vivo in humans.

RESULTS

Using small, simple, prototypical electrode chambers, attached to the ventral forearm surface, direct current iontophoresis at 0.25 mA/cm2 for periods of up to 1 hour, and a sensitive analytical procedure to measure the quantities of glucose extracted, it has been shown that iontophoretic sampling of glucose is feasible. However, the shorter periods (15 minutes or less) of extraction considered yield results which are "contaminated" (it is believed) by glucose that is a product of lipid metabolism within the skin. While this material is expected to complicate the initial calibration of the approach, the problem is effectively resolved within one hour, by which time the glucose arriving in the electrode chambers on the skin surface is expected to directly reflect the subcutaneous tissue concentration.

CONCLUSIONS

Based upon these initial observations, further investigation can now be directed towards optimization of electroosmotic flow and sampling time, improved reproducibility and the development of a practical assay methodology.

Effect of electroporation on transdermal iontophoretic delivery of luteinizing hormone releasing hormone (LHRH) in vitro

Electroporation, the creation of transient, enhanced membrane permeability using short duration (microseconds to millisecond) electrical pulses, can be used to increase transdermal drug delivery. The effect of an (electroporative) electric pulse (1000 V, tau = 5 msec) on the iontophoretic transport of LHRH through human skin was studied in vitro. Fluxes achieved with and without a pulse under different current densities (0- 4 mA/cm2) were compared. The results indicated that the application of a single pulse prior to iontophoresis consistently yielded higher fluxes (5-10 times the corresponding iontophoretic flux). For example, at 0.5 mA/cm2 fluxes were 0.27 +/- 0.08 and 1.62 +/- 0.05 micrograms/hr/cm2 without and with the pulse, respectively. At each current density studied, the LHRH flux decreased after iontophoresis, approaching pre-treatment values. The results show that electroporation can significantly and reversibly increase the flux of LHRH through human skin. These results also indicate the therapeutic utility of using electroporation for enhanced transdermal transport.

Erosion of a new family of biodegradable polyanhydrides

Studies investigating the erosion mechanism of the newly developed poly (fatty acid dimer: sebacic acid) polyanhydride (p:[FAD:SA]) are described. The overall erosion of different monomer compositions of p(FAD:SA) copolymers was examined to determine whether and to what extent copolymer properties affected polymer erosion. Increasing the hydrophobic monomer (FAD) content up to 50 wt% in the copolymer resulted in longer erosion, whereas further increases up to 70 wt% decreased the erosion period. Polymer crystallinity depended on copolymer FAD content. Copolymer degradation was studied by examining anhydride bond hydrolysis using infrared spectroscopy. Much faster hydrolysis was found in p(FAD:SA) 70:30 compared with more crystalline copolymers of higher SA content. Light microscopy indicates the presence of an erosion zone, a distinct area where mass loss occurs. This erosion zone moves from the outside toward the interior of the polymer matrix. It plays an important role in erosion because any water or monomer must diffuse through this eroded layer.

[A case of bronchogenic cyst in the esophageal wall]

A 73-year-old man with a right aortic arch was admitted because of stridor and dyspnea. We diagnosed a cervico-mediastinal cyst associated with bilateral recurrent laryngeal nerve palsy. Median sternotomy revealed a cystic tumor located in the esophageal wall. Microscopic examination of the resected cyst showed cartilage, smooth muscle and mucous gland, so the final diagnosis was bronchogenic cyst. The bilateral recurrent laryngeal nerve palsy was caused by chronic pressure from the cyst. Mediastinal cysts should be found and treated as early as possible, because these cysts may sometimes cause fatal complications.

Radiosensitive craniopharyngiomas: the role of radiosurgery

Clinical characteristics of radiosensitive craniopharyngiomas and histologically identical tumours were re-evaluated from among 53 patients. There were 9 squamous cell type and 3 mixed type tumours. Early effects of radiosurgery for two recent cases are reported. Radiosurgery may have an important role to play in the treatment of craniopharyngiomas, especially of the squamous cell type.

[Mediastinal hematoma due to thymoma hemorrhage--a case report]

A 70-year-old man came to our hospital complaining mainly of acute dyspnea. A chest X-ray, echocardiogram, and chest CT showed a mediastinal mass, and pericardial and pleural effusions. A thoracotomy revealed a cystic tumor along the thymus. The tumor contained bloody fluid, coagula, and fibrin calculi. Rapid specimens showed no tumor cells and the hematoma was assumed to have been caused by the thymus. Therefore, a thymectomy was performed and as much of the hematoma as possible was removed. After the operation, a careful pathological examination revealed a thymoma with a diameter of about 7 mm. In addition, coagula and fibrin calculi contained some tissue from the thymoma, and the diagnosis was made that a mediastinal hematoma had formed due to hemorrhage from the thymoma. Several cases of mediastinal tumor of cyst hemorrhages in the thorax have been reported. However, only a few cases of thymomal hemorrhages in the thorax have been reported; one case each of mediastinal hematoma, hemothorax, and cardiac tamponade. Great care is necessary when dealing with atraumatic mediastinal hematomas if malignant tumors such as thymoma are present.

[A case of multiple pulmonary arteriovenous fistulae associated with splenic abscess]

A 51-year-old female was admitted with high grade fever, cyanosis and hypoxemia. The chest X-ray showed nodular shadows on bilateral lung fields. Beta-streptococci were found on culture from the blood, and the fever fell after administration of both antibiotics and corticosteroid. Pulmonary angiography revealed four arteriovenous fistulae on bilateral lung fields. On abdominal ultrasonography and CT scan, a hypoechoic lesion with an irregular wall and varying internal echogenicity was detected within the spleen. This lesion changed in size and shape during the clinical course and diminished with improvement in the patient's condition. These findings were compatible with splenic abscess. Splenic abscess with pulmonary arteriovenous fistulae is rare.

[A case of malignant mesothelioma of the pleura]

An operative case of malignant localized mesothelioma of the pleura, a 63-year-old male, came to our clinic with the chief complaint of hemosputa. On suspicion of lung tumor, right upper lobectomy and lymph node cleaning were performed. The tumor was embedded in the lung; there was no infiltration into the chest wall. After the operation, radiotherapy was added but tumor recurrence occurred in the 5th month, and the patient died 7 months after surgery. From the form of the recurrence it was considered a diffuse-type transition case. The prognosis of this disease is known to be poor, but since there have also been cases of long survival, cases of resection are studied in Japan. Based on macroscopic tumor findings, cases of occurrence in the visceral pleura have poor prognosis if embedded in the lung, while cases of occurrence in the parietal pleura have varied prognoses, but the differentiation line is yet unclear. Among six cases of diffuse-type transition, including this case, five cases were of the histological type which included the epithelial component. Further study of these cases is necessary in the near future.

New bioabsorbable pledgets and non-woven fabrics made from polyglycolide (PGA) for pulmonary surgery: clinical experience

A new type of bioabsorbable pledget made from non-woven fabric of polyglycolide (PGA) fibers has been developed. After the in vivo implantation test using dogs, samples were subject to clinical evaluations in pulmonary operations in four hospitals. The total number of trial cases was 50; in 11 cases pledgets were used for repair of the bronchus and in 39 cases for lung fistulas or defects of the pleurae. Compared with the conventional nonabsorbable pledgets, these PGA pledgets showed satisfactory results. In particular, for cases of emphysematous pulmonary diseases the application of the PGA pledgets and non-woven fabrics made the post-operative air-leakage duration short. In all these 50 cases neither side effect nor complication was observed. This evaluation suggests that PGA pledgets and non-woven fabric are an acceptable and even better alternative to conventional nonabsorbable pledgets for the pulmonary surgery.

Saccadic eye movements evoked by microstimulation of the fastigial nucleus of macaque monkeys

1. Systematic exploration throughout the deep cerebellar nuclei and white matter disclosed that the region from which saccadic eye movements (saccades) were evoked with weak currents (less than 10 microA) was confined to the fastigial nucleus and the adjacent white matter. 2. When an electrode for stimulation was advanced in the cerebellum, saccades were evoked in the direction of the stimulated side (ipsilateral saccades) as it entered the low-threshold region. In some tracks, particularly when the electrode was advanced in the medial portion of the fastigial nucleus, the direction of the evoked saccades changed from the ipsilateral to the contralateral. 3. The mappings with microstimulation disclosed that the ipsilateral saccades were elicited from a relatively wide region that included almost the full extent of the fastigial nucleus. The low-threshold region continued in the white matter caudally into vermal lobule VII and rostrally into the dorsal aspect of the brachium conjunctivum. On the other hand, the contralateral saccades were evoked from a relatively circumscribed region in the ventromedial portion of the fastigial nucleus. 4. The reversal in the direction of the horizontal component occurred always in a narrow zone in the core of the fastigial nucleus. The caudal part of this zone coincided with an ellipsoidal region where anterogradely labeled axons of the Purkinje cells terminated when HRP was injected into vermal lobule VII. 5. When bicuculline (0.2-1 microgram) was injected in the ellipsoidal region, the ipsilateral saccades evoked from the dorsocaudal aspect of the region were suppressed for several hours. On the other hand, the contralateral saccades evoked from the ventromedial portion of the fastigial nucleus were either unchanged or enhanced. 6. Because the ipsilateral saccades were suppressed by bicuculline, they were most probably evoked by stimulation of the presynaptic component of gamma-amino-butyric acid-(GABA) mediated synapses, namely the axons of Purkinje cells. 7. Because stimulation of the presynaptic component of the inhibitory synapses evoked ipsilateral saccades, activation of the postsynaptic component would evoke contralateral saccades. In fact, the distribution of the fastigial sites yielding contralateral saccades coincided with the course of axons of fastigial neurons arising in the ellipsoidal region. It is most likely, therefore, that the contralateral saccades were evoked by stimulation of fastigial neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of hemangiopericytic meningiomas by immunohistochemistry, electron microscopy and cell culture

Intracranial hemangiopericytic meningiomas (HM) from seven patients were examined by immunostaining, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and cell culture. Positive staining for Factor VIII-related antigen was restricted to capillary endothelial cells. There was no reaction with anti-glial fibrillary acidic protein (GFAP) serum or anti-S-100 protein serum. In these neoplasms TEM displayed extracellular basement membrane-like material (BMLM), cytoplasmic intermediate filaments (IF) associated with a dense body, dilated rough-surfaced endoplasmic reticulum containing BMLM, a small area of interdigitation of cell membranes, and a unique intercellular punctate or linear density. By SEM these tumors had intercellular shell-like or reticular structures and irregularly branched capillaries which were compressed by ellipsoidal- or carrot-shaped tumor cells. Short-term monolayer culture showed rapid and vigorous growth of tumor cells, and the formation of pseudolumens but not of whorls. The TEM of cultured cells also showed cytoplasmic IF associated with the dense body. By SEM the cultured cells were flat and had a discoid nucleus with conspicuous nucleolar hillocks. Our results show that HM are mainly poorly specialized mesenchyme-related tumors of the meninges; some possess a potential for aggressive growth and some for differentiation into smooth muscle cells. Further study is needed to determine their histogenesis.

Induction of squamous cell carcinoma with 3,4-benzo[a]pyrene in the human bronchus transplanted into nude mice

By the intraluminal injection of 3,4-benzo[a]pyrene into human bronchial grafts in nude mice, squamous cell carcinoma was induced in one bronchial graft out of 17 benzo[a]pyrene-treated grafts. As benzo[a]pyrene is one of the most common carcinogens in the human environment, this experimental system should serve as an excellent model system for studying the process of carcinogenesis in the human respiratory tract.