Flow cytometric analysis of immunoprecipitates: high-throughput analysis of protein phosphorylation and protein-protein interactions

BACKGROUND

Activation-induced protein phosphorylation can be studied by Western blotting, but this method is time consuming and depends on the use of radioactive probes for quantitation. We present a novel assay for the assessment of protein phosphorylation based on latex particles and flow cytometry.

METHODS

This method employs monoclonal antibodies coupled to latex particles to immobilize protein kinase substrates. Their phosphorylation status is assessed by reactivity with phosphoepitope-specific antibodies. The amount of immobilized protein on the particles was analyzed by direct or indirect immunofluorescence with antibodies to nonphosphorylated epitopes.

RESULTS

The assay allowed measurement of phosphorylation of multiple protein kinase substrates in stimulated T cells, including the zeta chain of the T-cell receptor, ZAP-70, CD3, CD5, SHP-1, and ERK-2, using 1-3 microg of total cell protein per sample. The assay provided high resolution of kinetics of phosphorylation and dephosphorylation. Interactions of protein kinase substrates with associated signaling molecules were demonstrated.

CONCLUSIONS

The novel assay allows high-throughput quantitative measurement of protein modifications during signal transduction.

A phase I trial of docetaxel and gemcitabine in patients with advanced cancer

BACKGROUND

Docetaxel and gemcitabine are active in a broad range of malignancies. The objective of this phase I trial was to determine the maximally tolerated doses of the combination of docetaxel and gemcitabine.

PATIENTS AND METHODS

Patients with advanced cancer, WHO performance status 0-2, who had received up to one prior chemotherapy regimen were treated with gemcitabine on days 1 and 8 and docetaxel on day 8 repeated every 21 days. Prophylactic ciprofloxacin was commenced on day 11 of each cycle and continued until the neutrophil count reached 1.0 x 10(9)/l. G-CSF was not administered. Dose levels studied were docetaxel/gemcitabine: 60/800, 60/1000, 75/1000, 75/1200, 85/1200 and 100/1200 mg/m2.

RESULTS

Thirty-nine patients were entered and all were assessable for toxicity. The highest administered dose level was 100 mg/m2 docetaxel and 1200 mg/m2 gemcitabine with dose limiting toxicities of febrile neutropenia, grade 4 neutropenia > or = 7 days, grade 4 thrombocytopenia, grade 3 stomatitis and/or grade 3 fatigue in three out of six patients. Treatment was well tolerated (40 cycles) in the 10 patients treated at the recommended dose level (85/1200) with only a single episode of febrile neutropenia and grade 3 or 4 non-hematologic toxicity was infrequent. There was no significant pulmonary toxicity. Responses were seen in a range of malignancies including non-small-cell lung cancer.

CONCLUSIONS

The recommended dose level of 85 mg/m2 docetaxel and 1200 mg/m2 gemcitabine has a favourable toxicity profile and is suitable for further investigation in phase II trials. This non-platinum containing regimen warrants further investigation as a potential alternative to platinum containing regimens in non-small-cell lung cancer and other malignancies.

Absence of selection against aneuploid mouse sperm at fertilization

Is there selection against aneuploid sperm during spermatogenesis and fertilization? To address this question, we used male mice doubly heterozygous for the Robertsonian (Rb) translocations Rb(6. 16)24Lub and Rb(16.17)7Bnr, which produce high levels of sperm aneuploid for chromosome 16, the mouse counterpart of human chromosome 21. The frequencies of aneuploid male gametes before and after fertilization were compared by analyzing approximately 500 meiosis II spermatocytes and approximately 500 first-cleavage zygotes using fluorescence in situ hybridization with a DNA painting probe mixture containing three biotin-labeled probes specific for chromosomes 8, 16, and 17 plus a digoxigenin-labeled probe specific for chromosome Y. Hyperhaploidy for chromosome 16 occurred in 20.0% of spermatocytes and in 21.8% of zygotes. Hypohaploidy for chromosome 16 occurred in 17.0% and 16.7% of spermatocytes and zygotes, respectively. In addition, there was no preferential association between chromosome 16 aneuploidy and either of the sex chromosomes, nor was there an elevation in aneuploidy for chromosomes not involved in the Rb translocations. These findings provide direct evidence that there is no selection against aneuploid sperm during spermiogenesis, fertilization, and the first cell cycle of zygotic development.

Phase I and subsequent phase II study of filgrastim (r-met-HuG-CSF) and dose intensified cyclophosphamide plus epirubicin in patients with non-Hodgkin's lymphoma and advanced solid tumors

BACKGROUND

To define a maximum tolerated dose (MTD) for the combination of epirubicin and cyclophosphamide with filgrastim (r-met-HuG-CSF) in patients with advanced solid tumors and non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Thirty-five patients with advanced solid tumors were enrolled in stages I and II. Twenty-one patients were treated in stage I in sequential cohorts of at least three patients at increasing dosage levels of cyclophosphamide and epirubicin, for up to six cycles every 21 days. At the completion of stage I, a MTD for epirubicin was established. Fourteen patients were treated in stage II, in cohorts of three or more. The epirubicin dose remained constant at the MTD dosage from stage I. Cyclophosphamide was further dose-escalated to establish its MTD. Twenty-one patients with previously untreated non-Hodgkin's lymphoma were treated in stage III with the MTD established in the prior stages.

RESULTS

The MTD in stage I was epirubicin 150 mg/m2 and cyclophosphamide 1500 mg/m2 with cumulative neutropenia as the dose-limiting toxicity (DLT). Cumulative thrombocytopenia prevented further dose-escalation of cyclophosphamide in stage II. The stage III regimen consisted of six, 21-day cycles of epirubicin 150 mg/m2, cyclophosphamide 1500 mg/m2, vincristine 2 mg, and prednisolone 100 mg for five days with filgrastim support. Nineteen of twenty-one patients (90%) completed six cycles of treatment, eight (38%) without dose reduction. Common toxicity criteria (CTC) grade 4 neutropenia (neutrophil nadir < 0.5 x 10(9)/l) was documented in 85 of 118 cycles (72%). Neutropenic fever was documented in 17 of 21 patients (81%) on at least one occasion. Severe thrombocytopenia (< 25 x 10(9)/l) was seen in fourteen of 118 cycles (12%) and increased with cycle number. There was no significant non-hematological toxicity.

CONCLUSION

Significant dose-escalation of epirubicin and cyclophosphamide was possible with filgrastim support. The MTD achieved was approximately double that of standard-dose therapy. This study forms the basis of an ongoing randomized study evaluating dose-intensification in intermediate grade NHL.

Near-field speech intelligibility in chemical-biological warfare masks

It is common knowledge among field personnel that poor speech intelligibility can occur when chemical-biological warfare (CBW) masks are worn: indeed, many users resort to hand signals for person-to-person communicative purposes. This study was conducted in an effort to generate basic information about the problem; its focus was on the assessment of, and comparisons among, the communicative efficiency of seven different CBW units. Near-field word intelligibility was assessed by use of rhyming minimal contrast tests; user and acoustic restrictions were studied by means of diadochokinetic tests and system frequency response. The near-field word intelligibility of six American-designed masks varied somewhat, but overall it was reasonably good; however, a Russian unit did not perform well. Second, three of the U.S. masks were found to produce less physiological restraint than the others, and the Soviet mask produced the greatest physiological restraint. Finally, a few of the CBW masks also exhibited very low levels of acoustic distortion. Accordingly, it was concluded that two of the several configurations studied exhibited superior features. Other factors being equal, they can be recommended for field use and as a basis for the development of future generations of CBW masks. However, it also should be noted that although these devices provided reasonably good speech intelligibility when the listener was close to the talker, they do not appear to do so even at minimal distances.

A randomised phase III study of accelerated or standard fraction radiotherapy with or without concurrent carboplatin in inoperable non-small cell lung cancer: final report of an Australian multi-centre trial

PURPOSE

To investigate the effects separately and together of (a) shortening overall treatment time and (b) giving concurrent carboplatin in patients having radical radiotherapy for inoperable non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Between April 1989 and May 1995, 204 patients with medically inoperable or technically unresectable NSCLC localised to the primary site and regional lymph nodes were randomised to receive one of four treatments using a 2 x 2 factorial design: standard radiotherapy, 60 Gy in 30 fractions in 6 weeks (R6); accelerated radiotherapy, 60 Gy in 30 fractions in 3 weeks (R3); standard radiotherapy as in R6 with carboplatin 70 mg/m2/day for 5 days during weeks 1 and 5 of radiotherapy (R6C); accelerated radiotherapy as in R3 with carboplatin 70 mg/m2/day for 5 days during week 1 of radiotherapy (R3C).

RESULTS

The estimated median survival of all randomised patients was 15.7 months and estimated 2-year survival was 31%. The longest survival was seen in patients randomised to R6C (median 20.3 months, 41% surviving at 2 years) but there were no statistically significant differences between treatment arms or treatment factors (carboplatin versus no carboplatin, accelerated versus conventional radiotherapy). Haematological toxicity was significantly greater in patients treated with carboplatin and oesophageal toxicity was significantly greater and more protracted in patients treated with accelerated radiotherapy.

CONCLUSIONS

This study failed to show a significant survival advantage for any of the treatment arms or factors. Halving overall treatment time resulted in significantly greater oesophageal toxicity with no suggestion of a survival advantage.

Production of 1alpha,25-dihydroxy-3-epi-vitamin D3 in two rat osteosarcoma cell lines (UMR 106 and ROS 17/2.8): existence of the C-3 epimerization pathway in ROS 17/2.8 cells in which the C-24 oxidation pathway is not expressed

The secosteroid hormone 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] is metabolized into calcitroic acid through the carbon 24 (C-24) oxidation pathway. It is now well established that the C-24 oxidation pathway plays an important role in the target tissue inactivation of 1alpha,25(OH)2D3. Recently, we reported that 1alpha,25(OH)2D3 is also metabolized into 1alpha,25-dihydroxy-3-epi-vitamin D3 [1alpha,25(OH)2-3-epi-D3] through the carbon 3 (C-3) epimerization pathway in human keratinocytes, human colon carcinoma cells (Caco-2), and bovine parathyroid cells. In a previous study, it was demonstrated that 1alpha,25(OH)2-3-epi-D3 when compared to 1alpha,25(OH)2D3 was less active in stimulating intestinal calcium absorption, calcium mobilization from bone, and induction of calbindin D28k. These findings suggest that the C-3 epimerization pathway, like the C-24 oxidation pathway, may play a role in the target tissue inactivation of 1alpha,25(OH)2D3. In this study, we determined the relationship between the C-24 oxidation and the C-3 epimerization pathways by investigating the metabolism of 1alpha,25(OH)2D3 in two rat osteosarcoma cell lines (UMR 106 and ROS 17/2.8). These two cell lines differ from each other in their ability to metabolize 1alpha,25(OH)2D3 through the C-24 oxidation pathway. It has been previously reported that the C-24 oxidation pathway is expressed only in UMR 106 cells but not in ROS 17/2.8 cells. The results of our present study provide new evidence that both cell lines possess the ability to metabolize 1alpha,25(OH)2D3 into 1alpha,25(OH)2-3-epi-D3 through the C-3 epimerization pathway. Our results also reconfirm the findings of previous studies indicating that UMR 106 cells are the only ones which express the C-24 oxidation pathway out of the two cell lines studied. Furthermore, this study reveals for the first time that the C-3 epimerization pathway may become an alternate metabolic pathway for the target tissue inactivation of 1alpha,25(OH)2D3 in some cells, such as ROS 17/2.8, in which the C-24 oxidation pathway is not expressed.

Effect of caffeine consumption on tissue oxygen levels during hyperbaric oxygen treatment

Ten men were exposed to hyperbaric oxygen (HBO2), and their tissue oxygen levels were monitored after they drank either placebo or caffeine beverages. Transcutaneous tissue oxygen (PtcO2) monitor measurements in a normobaric air environment were initially obtained from transducers on the subject's chest and foot. The subjects then consumed either the caffeine (3 mg.kg-1) or the placebo beverage, and after 20 min the subjects were pressurized in a hyperbaric chamber to 2.36 atm abs (1 atm = 101.3250 kPa). The test subjects began breathing 100% oxygen at 2.36 atm abs, 30 min after administration of the experimental beverage, and continued for 30 min, after which the final chest and foot PtcO2 measurements were recorded (1 h after ingestion of the test drink). Each subject underwent a second hyperbaric exposure during which the alternate drink was administered (either the placebo or the caffeine), and PtcO2 measurements were again obtained. The increase in right foot PtcO2 values during HBO2 exposure was significantly smaller after caffeine consumption than after placebo (P = 0.0018).

Magnetic resonance imaging of shear wave propagation in excised tissue

The propagation of shear waves in ex vivo tissue samples, agar/gel phantoms, and human volunteers was investigated. A moving coil apparatus was constructed to generate low acoustic frequency shear perturbations of 50 to 400 Hz. Oscillating gradients phase-locked with the shear stimulus were used to generate a series of phase contrast images of the shear waves at different time-points throughout the wave cycle. Quantitative measurements of wave velocity and attenuation were obtained to evaluate the effects of temperature, frequency, and tissue anisotropy. Results of these experiments demonstrate significant variation in shear wave behavior with tissue type, whereas frequency and anisotropic behavior was mixed. Temperature-dependent behavior related mainly to the presence of fat. Propagation velocities ranged from 1 to 5 m/sec, and attenuation coefficients of from 1 to 3 nepers/unit wavelength, depending on tissue type. These results confirm the potential of elastic imaging attributable to the intrinsic variability of elastic properties observed in normal tissue, although some difficulty may be experienced in clinical implementation because of viscous attenuation in fat.

Nonviral interferon alpha gene therapy inhibits growth of established tumors by eliciting a systemic immune response

A plasmid expression system encoding murine IFN-alpha4 and complexed with a protective interactive noncondensing polymeric (PINC) delivery system was used for in vivo immunotherapy treatment of an immunogenic murine renal cell carcinoma, Renca, and a nonimmunogenic mammary adenocarcinoma, TS/A. Mice bearing established tumors were treated with IFN-alpha/polyvinylpyrrolidone (PVP) expression complexes via direct intratumoral injection. Up to 100% inhibition of tumor growth was observed in the treated mice. By using an optimal dose of 96 and 48 microg of formulated IFN-alpha plasmid for the treatment of Renca and TS/A, respectively, 30% (Renca) and 10% (TS/A) of the treated animals remained tumor free. Inhibition of tumor growth was dependent on activation of the immune system. The antitumor activity elicited by IFN-alpha gene therapy was abrogated when mice were selectively depleted of CD8+ T cells. By contrast, depletion of CD4+ T cells resulted in enhanced tumor rejection following IFN-alpha/PVP treatments. Finally, mice that remained tumor free following IFN-alpha gene therapy displayed immune resistance to a subsequent tumor challenge. These data provide evidence that IFN-alpha gene therapy can be used to induce an efficient antitumor response in vivo.

Trace analysis of SN-38 in human plasma by high-performance liquid chromatography

A reversed-phase high-performance liquid chromatographic method with fluorescence detection was developed and validated for the quantitation of SN-38, the active metabolite of irinotecan (CPT-11), a new anticancer drug. This method uses solid-phase extraction with a C18 column for sample clean-up and concentration following acidification of human plasma with two volumes of 0.1 M HCl. Using blank plasma spiked with SN-38, we found the assay to be linear over the concentration range of 10-500 pM (3.9-195 pg/ml) with acceptable total and within-day imprecision. The recovery of SN-38 ranged from 48.3% (10 pM) to 91.5% (500 pM) whereas that of the internal standard, 20-(S)-camptothecin, was 96.9% (500 pM). This method represents a sizeable increase in sensitivity over other published methods and is shown to be suitable for the measurement of 'trough' concentrations of SN-38 during the treatment of patients with a weekly regimen of irinotecan.

Phase II study of docetaxel and cisplatin in advanced non-small-cell lung cancer

PURPOSE

Docetaxel (Taxotere, Rhone-Poulenc Rorer, Antony, France) and cisplatin are two of the most active single agents used in the treatment of non-small-cell lung cancer (NSCLC). A recently reported phase I study of the combination of docetaxel and cisplatin recommended a dose of 75 mg/m2 of both drugs every 3 weeks for subsequent phase II study.

PATIENTS AND METHODS

Eligible patients were aged 18 to 75 years with a World Health Organization (WHO) performance status < or = 2 and life expectancy > or = 12 weeks, with metastatic and/or locally advanced NSCLC proven histologically or cytologically. Patients were not permitted to have received prior chemotherapy, extensive radiotherapy, or any radiotherapy to the target lesion and must have had measurable disease. Concurrent treatment with colony-stimulating factors (CSFs) or prophylactic antibiotics was not permitted. Docetaxel (75 mg/m2) in 250 mL 5% dextrose was given intravenously (i.v.) over 1 hour immediately before cisplatin (75 mg/m2) in 500 mL normal saline given i.v. over 1 hour in 3-week cycles. Premedication included ondansetron, dexamethasone, promethazine, and standard hyperhydration with magnesium supplementation.

RESULTS

A total of 47 patients, two thirds of whom had metastatic disease, were entered onto this phase II study. The majority of patients were male (72%) and of good (WHO 0 to 1) performance status (85%). All 47 patients were assessable for toxicity and 36 were for response. Three patients were ineligible and eight (17%) discontinued treatment because of significant toxicity. In assessable patients, the overall objective response rate was 38.9% (95% confidence limits [CL], 23.1% to 56.5%), 36.1% had stable disease, and 25% progressive disease. On an intention-to-treat analysis, the objective response rate was 29.8%. Median survival was 9.6 months and estimated 1-year survival was 33%. Significant (grade 3/4) toxicities included nausea (26%), hypotension (15%), diarrhea (13%), and dyspnea mainly related to chest infection (13%). One patient experienced National Cancer Institute (NCI) grade 3 neurosensory toxicity after eight cycles. Grade 3/4 neutropenia was common and occurred in 87% of patients, but thrombocytopenia > or = grade 3 was rare (one patient). Significant (grade 3/4) abnormalities of magnesium levels were common (24%). Febrile neutropenia occurred in 13% of patients and neutropenic infection in 11%, contributing to two treatment-related deaths. No neutropenic enterocolitis or severe fluid retention was reported.

CONCLUSION

Compared with other active regimens used in this setting, the combination of docetaxel and cisplatin in advanced NSCLC is an active regimen with a similar toxicity profile to other combination regimens.

Autism and maternally derived aberrations of chromosome 15q

Of the chronic mental disabilities of childhood, autism is causally least well understood. The former view that autism was rooted in exposure to humorless and perfectionistic parenting has given way to the notion that genetic influences are dominant underlying factors. Still, identification of specific heritable factors has been slow with causes identified in only a few cases in unselected series. A broad search for genetic and environmental influences that cause or predispose to autism is the major thrust of the South Carolina Autism Project. Among the first 100 cases enrolled in the project, abnormalities of chromosome 15 have emerged as the single most common cause. The four abnormalities identified include deletions and duplications of proximal 15q. Other chromosome aberrations seen in single cases include a balanced 13;16 translocation, a pericentric inversion 12, a deletion of 20p, and a ring 7. Candidate genes involved in the 15q region affected by duplication and deletion include the ubiquitin-protein ligase (UBE3A) gene responsible for Angelman syndrome and genes for three GABA(A) receptor subunits. In all cases, the deletions or duplications occurred on the chromosome inherited from the mother.

Epididymal sperm aneuploidies in three strains of rats detected by multicolor fluorescence in situ hybridization

A multicolor fluorescence in situ hybridization (FISH) method was developed to detect aneuploidy and diploidy in epididymal sperm of rats using DNA probes specific for chromosomes 4 and Y. Fourteen healthy young-adult rats from three strains were evaluated: inbred Fisher 344/N/ehs, outbred Sprague-Dawley, and outbred WU Wistar/CPB. The hybridization efficiency of the FISH procedure was > 99.9%, the sex-ratio in sperm was approximately 1 as expected, and there was no significant variation among two independent scorers. No significant variations were detected within or among strains in the frequencies of sperm disomy for chromosome 4 (1-6.5 per 10,000 cell per animal) or the Y chromosome (0-2.5 per 10,000 cells per animal). There was a trend toward increased variation among Wistar rats. The frequencies of sperm-carrying hyper- and hypohaploidy for chromosome 4 were similar, suggesting a symmetrical mechanism of chromosome gain and loss during meiosis. The frequencies of Y-Y-4-4 sperm, which represent genomic meiosis II errors, did not differ significantly across strains (0.1-0.7 per 10,000 cells per strain). This FISH method for detecting aneuploidy in rat epididymal sperm provides a promising interspecies biomarker of male germ cell aneuploidy and introduces the rat as an animal model for investigating the heritable risk to offspring associated with paternal genotype, physiology, and exposure to environmental mutagens. There appear to be no significant differences among young healthy rats, mice, and men in the baseline frequencies of sperm with Y chromosomal disomy, the only chromosome for which data currently exists for all three species.

Clenbuterol induces cardiac hypertrophy with normal functional, morphological and molecular features

OBJECTIVE

Several pharmacological agents have been shown to produce 'physiological' or 'pathological' hypertrophy based on their functional characteristics. The aim of this study was to examine the features of cardiac hypertrophy induced by the selective beta 2-adrenergic agonist, clenbuterol.

METHODS

Cardiac hypertrophy was induced in 7-week-old Sprague-Dawley rats by daily injections of clenbuterol for 3 weeks. Thyroxine and isoproterenol were also used to produce cardiac hypertrophy to serve as positive controls for physiological and pathological hypertrophy, respectively. Left ventricular function was determined using an isolated rat heart preparation. Ventricular samples were used for morphological examination while interstitial collagen was measured using high-pressure liquid chromatography. Expression of sarcoplasmic reticulum Ca(2+)-ATPase2a (SERCA2a) and phospholamban (PLB) were measured by dot blot analysis.

RESULTS

Clenbuterol treatment induced 26% left ventricular hypertrophy. These hearts demonstrated normal systolic isovolumic parameters and diastolic (active relaxation and passive stiffness) function. In addition, left ventricular concentration of collagen and morphology was normal as were the expression of SERCA2a and PLB mRNA.

CONCLUSION

These results suggest that clenbuterol-induced hypertrophy is 'physiological' in terms of its function, extracellular structure and gene expression.

A simple inflammation model that distinguishes between the actions of anti-inflammatory and anti-rheumatic drugs

OBJECTIVE AND DESIGN

To determine the effects of anti-inflammatory and anti-rheumatic drugs on paw swelling and changes in plasma levels of acute phase proteins (APPs) during acute inflammation in the rat.

MATERIALS AND METHODS

Inflammation was induced in rats by the injection of adjuvant and the animals were bled five days later and plasma levels of seromucoid, haptoglobin, caeruloplasmin and albumin were determined spectrophotometrically using a Cobas-bio centrifugal analyzer. The effects of daily administration of a variety of drugs used to treat arthritis were determined on paw swelling and APP levels.

RESULTS

Injection of the adjuvant induced a pronounced change in APP levels which correlated with the increase in paw swelling. In general, the NSAIDs tested significantly reduced paw swelling and significantly increased levels of haptoglobin and caeruloplasmin in a dose-related manner. Two dose-levels of steroids were administered, the higher dose reduced swelling, and reduced levels of seromucoid, haptoglobin and caeruloplasmin, but raised albumin levels; the lower dose also reduced paw swelling, but the only change in APPs was increased albumin levels. Anti-rheumatic drugs such as gold salts reduced levels of some APPs (seromucoid, haptoglobin and caeruloplasmin) without reducing paw swelling. Immunomodulators had a variety of effects on inflammation and APPs depending on mechanism of action.

CONCLUSIONS

The different classes of anti-inflammatory/anti-rheumatic drug tested show distinct profiles of activity against APPs and paw swelling. These differential effects may result from modulation of cytokine activity.

Effects of thyroid hormone on embryonic oligodendrocyte precursor cell development in vivo and in vitro

The oligodendrocyte precursor cell divides a limited number of times before terminal differentiation. The timing of differentiation depends on both intracellular mechanisms and extracellular signals, including mitogens that stimulate proliferation and signals such as thyroid hormone (TH) and retinoic acid (RA) that help trigger the cells to stop dividing and differentiate. We show here that, both in vivo and in vitro, TH is required for the normal development of rodent optic nerve oligodendrocytes, although in its absence some oligodendrocyte development still occurs, perhaps promoted by signals from axons. We also demonstrate that TH from both mother and pup plays a part in oligodendrocyte development in vivo. Finally, we show that precursors in embryonic nerve cultures differ from those in postnatal cultures in two ways: they respond much better to TH than to RA, and they respond more slowly to TH, suggesting that oligodendrocyte precursor cells mature during their early development.

Ro 32-3555, an orally active collagenase inhibitor, prevents cartilage breakdown in vitro and in vivo

1. Ro 32-3555 (3(R)-(cyclopentylmethyl)-2(R)-[(3,4,4-trimethyl-2,5-dioxo-1- imidazolidinyl)methyl]-4-oxo-4-piperidinobutyrohydroxamic acid) is a potent, competitive inhibitor of human collagenases 1, 2 and 3 (Ki values of 3.0, 4.4 and 3.4 nM, respectively). The compound is a selective inhibitor of collagenases over the related human matrix metalloproteinases stromelysin 1, and gelatinases A and B (Ki values of 527, 154 and 59 nM, respectively). 2. Ro 32-3555 inhibited interleukin-1 alpha (IL-1 alpha)-induced cartilage collagen degradation in vitro in bovine nasal cartilage explants (IC50 = 60 nM). 3. Ro 32-3555 was well absorbed in rats when administered orally. Systemic exposure was dose related, with an oral bioavailability of 26% at a dose of 25 mg kg-1. 4. Ro 32-3555 prevented granuloma-induced degradation of bovine nasal cartilage cylinders implanted subcutaneously into rats (ED50 = 10 mg kg-1, twice daily, p.o.). 5. Ro 32-3555 dosed once daily for 14 days at 50 mg kg-1, p.o., inhibited degradation of articular cartilage in a rat monoarthritis model induced by an intra-articular injection of Propionibacterium acnes. 6. Ro 32-3555 is a potential therapy for the treatment of the chronic destruction of articulating cartilage in both rheumatoid and osteoarthritis.