A humanized anti-CD3 antibody, HuM291, with low mitogenic activity, mediates complete and reversible T-cell depletion in chimpanzees.

BACKGROUND: An anti-CD3 antibody that reduces cytokine release syndrome (CRS) while maintaining immunosuppression would be a major advance in the treatment of acute allograft rejection. A humanized (Hu) anti-CD3 IgG2 Ab, HuM291 gamma2 M3 (HuM291; Protein Design Labs, Inc., Mountain View, CA), was engineered with mutations in the upper CH2 region of the Fc domain. The mutations were intended to reduce affinity for Fcgamma receptors, thought to be relevant to CRS. METHODS: In vitro studies using chimpanzee peripheral blood mononuclear cells (PBMCs) were conducted to characterize HuM291 and to establish an animal model. A multidose study was conducted in chimpanzees to evaluate the safety, pharmacokinetics, immunomodulatory activity, and immunogenicity of HuM291, when administered at doses ranging from 0.1 to 10 mg. RESULTS: HuM291 bound to and effectively downmodulated CD3 from chimpanzee PBMCs and stimulated substantially less cytokine secretion and proliferation of chimpanzee PBMCs compared with OKT3 (Orthoclone OKT3; Ortho Pharmaceutical Corp., Raritan, NJ). Multiple doses of HuM291 (0.1, 1.0, or 10 mg/dose) were not associated with adverse events, signs of toxicity, or CRS, despite cytokine release. HuM291 exhibited a long elimination t1/2 (81.5 hr) and, after three 10-mg doses, sustained serum concentrations > 1000 ng/ml were maintained for 1 week. Multiple 10-mg doses induced complete depletion of circulating CD2+CD3+ T cells for up to 10 days after the last dose; T cells recovered by Day 28. Anti-HuM291 Abs were observed in only 4 of 12 animals and were transient in 2 of those animals. CONCLUSIONS: In vitro, HuM291 is substantially less mitogenic than OKT3. In chimpanzees, HuM291 effectively depleted peripheral T cells without eliciting clinical signs of CRS, and recovered T cells were functionally normal.

Polymer heart valves.

Since the introduction of valve replacement surgery, research has aimed at creating a prosthesis that is safe, durable and effective. Neither of the two broad groups of valve currently available is ideal. A prosthetic valve is needed that does not suffer from the known disadvantages of calcification and premature failure (bioprostheses), and thrombogenicity (mechanical valves). Much progress has been made, both in design and materials, and an extensive range of polymer valves has been produced and tested both in vitro and in vivo. Unfortunately, each stage of development has encountered problems preventing successful clinical application. Many design difficulties have been addressed and potentially reduced to acceptable levels, but calcification remains a problem, although much less so than with bioprostheses. New developments in surface modification may hold the key to the elimination of thrombus and calcification, and early in vivo results are promising. It is likely that an effective and safe polymer valve will soon become a third clinical option. The historic aspects behind the development of polymer valves and the current state of research and evaluation are discussed.

Blood and tissue compatibility of modified polyester: thrombosis, inflammation, and healing.

Poly(ethylene terephthalate) (PET) has been reported in literature to be moderately inflammatory and thrombogenic. To moderate the inflammatory response, PET fabric was surface modified by either Fluoropassiv fluoropolymer (FC), or an RGD-containing peptide (RGD). Samples were subsequently autoclave sterilized and implanted subcutaneously in Sprague Dawley rats for 2 to 4 weeks. Retrieved samples were evaluated histopathologically for indications of material toxicity and healing. Minimal acute or chronic inflammation was associated with the fabrics after 2 and 4 week implant duration. However, fibroblast proliferation into FC modified fabric (PET/FC) was less than that into unmodified (PET) and RGD modified fabric (PET/RGD) after 4 weeks, suggesting that FC modification of PET may inhibit excessive tissue growth. Additional samples of modified and unmodified fabrics were placed in stainless steel mesh cages, which were then implanted subcutaneously for 4 weeks. Cellular exudate was extracted weekly and cell concentrations within the exudate measured. Total leukocyte count (TLC) (reflective of local inflammation) at 1 week for PET/RGD was greater than that for PET/FC and PET. TLCs after 4 week implant decreased for all sample groups. In a separate experiment, PET vascular grafts surface modified by either FC or RGD were contacted 1 h with blood using the baboon arteriovenous (AV) shunt model of thrombosis in both the presence and absence of heparin. Accumulation of 111In labeled platelets (reflective of thrombus accumulation) upon grafts was less in the presence of heparin (effect significant at p = 1.2 x 10(-6), two-way ANOVA). Accumulation (in the presence of heparin) upon PET/RGD was less (p = 0.19), and upon PET/FC significantly less (p = 0.016) than that upon the unmodified PET control, suggesting that FC modification of PET may inhibit thrombus accumulation.

Platelets and cardiopulmonary bypass.

Exposure of blood to an extracorporeal circulation, such as CPB, causes a variety of physiological responses. Haematological derangements are just one of many potential dangers to the patient who undergoes CPB. The paradox of CPB-related problems with the haematological system is that there are some factors tipping the balance towards a bleeding tendency, and others that favour a prothrombotic state. Both of these issues must be dealt with independently to create the safest environment for surgery. It has been demonstrated that platelets play a key role in both haemostatic dysfunction and thrombotic complications of CPB. Much has been achieved, both clinically and in the laboratory, in the understanding of the precise role platelets play in these events, but the exact mechanisms involved have yet to be completely identified. As research progresses, our understanding will increase, but until then clinical practice must be dictated by the current evidence available.

Cryosurgery as a treatment for prostate carcinoma: results and complications.

BACKGROUND: There has been a resurgence of interest in cryosurgical ablation of the prostate for the treatment of carcinoma. This is due to recent advances in cryosurgical technology, which have resulted in relatively lower morbidity. The objective of this study was to evaluate the effectiveness of ultrasound-guided cryosurgical ablation of prostate carcinoma. METHODS: Eighty-three patients who had biopsy-proven prostate carcinoma underwent cryosurgical ablation of their entire prostate gland. The initial group of 12 patients had their procedures performed under ultrasound guidance only. The other 71 patients had cryosurgery performed with temperature monitoring in combination with ultrasound guidance. Twelve patients who had positive biopsies underwent a second cryosurgical procedure. All patients had prostate specific antigen (PSA) levels measured at 3, 6, 12, 18, 24, and 30 months after cryosurgery. Ultrasound-guided sextant biopsies were performed at 3-6, 12-18, and 24 months. RESULTS: The median PSA dropped by 95%, from a preoperative value of 4.3 ng/mL to 0.2 ng/mL 30 months after cryosurgery. The authors experienced a high failure rate (positive biopsies) of 83% for the initial group of 12 patients who did not have temperature monitoring during the cryosurgical procedure. This was in contrast to a success rate of 90% (negative biopsies) for the next 71 patients, who did have temperature monitoring (P < 0.05, chi-square test). Twelve patients underwent a second cryosurgery, and the success rate for this group was 91% (11 of 12 patients). The combined success rate for both the first cryosurgery and the second was 94% (62 of 77 patients). Complications included urethral sloughing, urinary incontinence, impotence, bladder neck contracture, and bladder contracture. The majority of patients recovered rapidly from their cryosurgical procedures and were able to resume normal activities 3-4 weeks afterward. CONCLUSIONS: These preliminary results demonstrate that cryosurgical ablation of the prostate is a viable treatment option for prostate carcinoma. In the authors' experience, ultrasound alone may not be adequate for monitoring the entire cryosurgical procedure. The authors found that temperature monitoring shortened their learning curve, enabled them to freeze prostate tissue more aggressively, and may have contributed to their overall success.

High affinity type I interleukin 1 receptor antagonists discovered by screening recombinant peptide libraries.

Two families of peptides that specifically bind the extracellular domain of the human type I interleukin I (IL-1) receptor were identified from recombinant peptide display libraries. Peptides from one of these families blocked binding of IL-lalpha to the type I IL-1 receptor with IC50 values of 45-140 microM. Affinity-selective screening of variants of these peptides produced ligands of much higher affinity (IC50 approximately 2 nM). These peptides block IL-1-driven responses in human and monkey cells; they do not bind the human type II IL-1 receptor or the murine type I IL-1 receptor. This is the first example (that we know of) of a high affinity peptide that binds to a cytokine receptor and acts as a cytokine antagonist.

Uvulopalatopharyngoplasty and inferior sagittal mandibular osteotomy with genioglossus advancement for treatment of obstructive sleep apnea.

We prospectively studied nine patients with the obstructive sleep apnea (OSA) syndrome with polysomnography before and after combined (seven simultaneous and two sequential) uvulopalatopharyngoplasty and inferior sagittal mandibular osteotomy with genioglossus advancement as treatment for OSA. All patients had failed to tolerate nasal continuous positive airway pressure and had a respiratory disturbance index (RDI) > or = 20. All patients were found to have disproportionate pharyngeal anatomy with airway narrowing by cephalometrograms and/or fiberoptic nasopharyngoscopy. Following surgery there were significant reductions in the average numbers of respiratory events and significant improvements in average oxygen saturation measurements. When RDIs < or = 5 and < or = 10 are chosen as objective success benchmarks, the success rates are 67 percent (6/9) and 78 percent (7/9), respectively.

Postadsorptive transitions in fibrinogen adsorbed to polyurethanes: changes in antibody binding and sodium dodecyl sulfate elutability.

Residence time-dependent changes in fibrinogen after adsorption to six different polyurethanes were examined by measuring polyclonal antifibrinogen binding to the adsorbed protein. The amount of adsorbed fibrinogen that could be eluted by sodium dodecyl sulfate (SDS) was also measured. Baboon fibrinogen was first adsorbed from dilute plasma to the polymers, which were then stored in either buffer or buffered albumin solution prior to testing. Subsequently, the amount of antifibrinogen bound by the adsorbed fibrinogen was measured using a direct enzyme linked immunosorbent assay (ELISA). Alternatively, the surface with the adsorbed fibrinogen was soaked in a 3% SDS solution, and the amount of retained 125I-radiolabeled fibrinogen was measured. With increasing residence time, decreases in both antibody binding and the SDS elutability of the adsorbed fibrinogen occurred, but the rate of change was dependent on the polyurethane to which the fibrinogen was adsorbed. In addition, the antibody binding per unit of adsorbed fibrinogen, when measured immediately after the adsorption step, varied by approximately a factor of 3 among the various polyurethanes. When the protein-coated surfaces were stored in buffered albumin solution rather than buffer, the decrease in the reactivity of fibrinogen with residence time did not occur on some of the surfaces. This study shows that the chemical properties of the adsorbing surface influence the rate at which adsorbed fibrinogen undergoes change. The significance of the polymer-dependent changes in adsorbed fibrinogen with respect to blood reactions with polymers is discussed.

Adsorption of baboon fibrinogen and the adhesion of platelets to a thin film polymer deposited by radio-frequency glow discharge of allylamine.

Platelet adhesion under static and flow conditions from a washed platelet suspension containing albumin to a polymer deposited by radio-frequency glow discharge of allylamine vapour on a poly(ethylene terephthalate) substrate was measured. Electron spectroscopy for chemical analysis was used to characterize the surface. Fibrinogen adsorption from a series of dilute plasma solutions to radio-frequency glow discharge/allylamine, measured using 125I radiolabelled baboon fibrinogen, increased with decreasing plasma dilution to a level much higher than that previously observed on polyurethanes. Elutability by sodium dodecyl sulphate of fibrinogen adsorbed from dilute plasma also increased with increasing plasma concentration, but fibrinogen preadsorbed from plasma became non-elutable when surfaces were stored in buffer for 5 d before contact with sodium dodecyl sulphate. Platelet adhesion to substrates which had been pre-adsorbed with dilute plasma was measured using baboon platelets radiolabelled with 111In. Adhesion greatly decreased as the plasma concentration used for preadsorption increased, suggesting that non-specific platelet binding to the bare surface occurs when protein coverage is incomplete. Non-specific platelet binding was inhibited to varying degrees by preadsorption of different proteins to the surface. Platelet adhesion to surfaces preadsorbed with dilute (1.0%) baboon and human plasmas lacking fibrinogen (i.e. serum, heat-defibrinogenated plasma and congenitally afibrinogenemic plasma) was diminished compared with normal plasma. Addition of exogenous fibrinogen to the deficient plasma partially restored platelet adhesion to normal levels. Adhesion to surfaces preadsorbed with human plasma deficient in von Willebrand factor was comparable to that observed with normal plasma. The plasma preadsorption studies with fibrinogen deficient media suggested that adsorbed fibrinogen is necessary for platelet adhesion to the radio-frequency glow discharge/allylamine substrate at high protein coverage. However, since adhesion was greatly reduced when the plasma preadsorbed substrate was stored in buffer before platelet contact, the conformation of adsorbed fibrinogen is also important in mediating platelet adhesion to radio-frequency glow discharge.

Identification of a gene family regulated by transforming growth factor-beta.

We have identified two related genes whose mRNAs are increased after treatment with transforming growth factor-beta (TGF-beta 1). Mouse AKR-2B cells were treated with TGF-beta 1 in the presence of cyclohexamide and a cDNA library was subjected to differential screening. Several TGF-beta-induced genes (beta IG) were isolated and two of these, beta IG-M1 and beta IG-M2, were characterized. beta IG-M1 and beta IG-M2 RNAs were significantly increased after TGF-beta 1 treatment and both were superinduced in the presence of cyclohexamide. cDNA sequence analysis of beta IG-M1 showed that it encoded a 379-amino-acid protein which was 81% homologous to CEF-10, a v-src and TPA-inducible gene, and identical to cyr61, a gene induced by serum in growth-arrested BALB-3T3 cells. cDNA sequence analysis of beta IG-M2 showed that it encoded a 348-amino-acid protein that was 50% homologous to beta IG-M1. Thirty-eight cysteine residues are conserved between beta IG-M1 and beta IG-M2, which are clustered at the amino and carboxy ends: The middle regions of the two proteins are cysteine free and display the highest degree of nonhomology. Both proteins contain an amino-terminal cysteine-rich motif common to insulin-like growth factor binding proteins and a carboxy-terminal domain with strong homology to a motif found near the carboxy-terminal of the malarial circumsporozoite protein which may be involved in cell adhesion. The regulation of mRNA encoding these proteins by TGF-beta 1 suggests that they may be involved in mediating some of the pleiotropic effects of this multipotent modulator of cell growth and differentiation.

Baboon fibrinogen adsorption and platelet adhesion to polymeric materials.

The role of fibrinogen in mediating platelet adhesion to polymers exposed to blood plasma was studied by comparison of the effect of plasma dilution on fibrinogen adsorption and platelet adhesion, and by the use of coagulation factor deficient plasmas. Polyetherurethane substrates were first preadsorbed with dilute plasma, then contacted with washed platelets suspended in a modified, apyrase containing Tyrode's buffer. Platelet adhesion was studied under static conditions in Multiwell dishes, and also under shearing conditions using a parallel plate perfusion chamber. Fibrinogen adsorption and platelet adhesion were measured using 125I radiolabeled baboon fibrinogen and 111In radiolabeled baboon platelets, respectively. Surfaces were characterized by electron spectroscopy for chemical analysis (ESCA). When fibrinogen adsorption to Biomer was measured after 2 h contact with a series of dilute plasma solutions under static conditions, a peak in adsorption was observed from 0.26% plasma, i.e., adsorption was greater from 0.26% plasma than from either more or less dilute plasma. A peak in subsequent platelet adhesion to the plasma preadsorbed surfaces, measured after 2 h static incubation with washed platelets, was also observed but occurred on Biomer preadsorbed with 1.0% plasma. When fibrinogen adsorption was measured after 5 min contact under shearing conditions, the fibrinogen adsorption peak occurred on surfaces that had been exposed to 1.0% plasma. A peak in platelet adhesion to these preadsorbed surfaces, measured after 5 min contact with the platelet suspensions under shearing conditions, was observed on Biomer preadsorbed with 0.1% plasma. Shifts between the positions of the peaks in protein adsorption and platelet adhesion occurred on other polymers tested as well. Platelet adhesion was almost completely inhibited when baboon and human plasmas lacking fibrinogen (i.e., serum, heat defibrinogenated plasma, and congenitally afibrinogenemic plasma) were used. Platelet adhesion was restored to near normal when exogenous fibrinogen was added to fibrinogen deficient plasmas. Adhesion was also inhibited completely when a monoclonal antibody directed against the glycoprotein IIb/IIIa complex was added to the platelet suspension. Platelet adhesion to surfaces preadsorbed to von Willebrand factor deficient plasma was the same as to surfaces preadsorbed with normal plasma. While it appears that surface bound fibrinogen does mediate the initial attachment of platelets to Biomer, the observation that the fibrinogen adsorption and platelet adhesion maxima do not coincide exactly also suggests that the degree of subsequent platelet adhesion is dictated not only by the amount of surface bound fibrinogen but also by its conformation.

Postadsorptive transitions in fibrinogen adsorbed to biomer: changes in baboon platelet adhesion, antibody binding, and sodium dodecyl sulfate elutability.

Residence-time-dependent changes in fibrinogen after its adsorption to Biomer were examined by measuring platelet adhesion and antibody binding to the adsorbed protein, and the amount of adsorbed fibrinogen which could be eluted by sodium dodecyl sulfate (SDS). Baboon fibrinogen was first adsorbed (from either pure solution or dilute plasma) to Biomer, which was then stored in either buffer or buffered albumin solution prior to testing. Subsequently, the adherent protein layer was either probed for fibrinogen capable of mediating platelet adhesion using 111In radiolabeled, washed platelet suspensions under both static and shearing conditions, or for fibrinogen capable of binding antibody using a direct enzyme linked immunosorbent assay (ELISA). Alternatively, the surface with the adsorbed protein layer was soaked in a 3% SDS solution, and the amount of 125I radiolabeled fibrinogen retained was measured. Decreases in platelet and antibody binding, and in the SDS elutability of the adsorbed fibrinogen after it was stored in buffer were detected, although different rates of decrease were observed for each method. When the protein-coated surfaces were stored in buffered albumin solution rather than buffer, the decrease in the reactivity of fibrinogen was prevented. While each of the three assays measures a different property of adsorbed fibrinogen, this study suggests that the adherent protein undergoes time dependent conformational changes which render it less reactive toward platelets and antibodies, and more resistant to elution by SDS.

Treatment of recurrent Clostridium difficile colitis with vancomycin and Saccharomyces boulardii.

Recurrence of Clostridium difficile-associated diarrhea and pseudomembranous colitis occurs in up to 20% of patients after standard therapy. In these patients, subsequent recurrences are even more frequent. Saccharomyces boulardii, a nonpathogenic yeast, was found to be effective in preventing clindamycin cecitis recurrence in an animal model. We performed an open trial of S. boulardii to evaluate its efficacy in treating recurrences of C. difficile-associated colitis in humans. Thirteen patients with recurring C. difficile cytotoxin-positive diarrhea (who had an average of 3.6 previous recurrences) were treated with 10 days of vancomycin and a 30-day course of S. boulardii. Eleven (85%) had no further recurrences. S. boulardii may have a role in treating recurrent C. difficile diarrhea and colitis.

Protection of macaques against simian AIDS by immunization with a recombinant vaccinia virus expressing the envelope glycoproteins of simian type D retrovirus.

Simian AIDS (SAIDS) is an endemic disease of macaques that shares many characteristics with AIDS in humans. SAIDS is etiologically linked to infection by a type D retrovirus, SAIDS retrovirus (SRV). Immunization with an inactivated whole-virus vaccine was shown to protect macaques against infection by SRV serotype 1. To identify the antigen(s) responsible for eliciting protective immunity, we have constructed a recombinant vaccinia virus (v-senv5) that expresses the envelope glycoproteins of SRV serotype 2 (SRV-2/W). Pig-tailed macaques (Macaca nemestrina) immunized with v-senv5 showed lymphoproliferative responses to purified SRV-2/W. They also generated antibodies that neutralized SRV-2/W infectivity in vitro and mediated antibody-dependent cellular cytotoxicity against SRV-2-infected cells. Four v-senv5-immunized animals, together with four control animals, were challenged intravenously with 5 x 10(3) tissue culture infectious doses of SRV-2/W. As early as 2 weeks after challenge, three of four control animals became viremic, and two of these three animals also seroconverted. The animal that was viremic but remained antibody negative died of symptoms of SRV infection 6 1/2 weeks after challenge. In contrast, all four v-senv5-immunized animals remained healthy, virus-free, and seropositive against only the immunizing envelope antigens. These results indicate that immunization with a recombinant vaccinia virus expressing the envelope antigens of SRV-2/W protects primates from infection by a retrovirus that causes immunodeficiency diseases.

Sex pheromones in snakes.

The majority of pheromones identified to date are insect pheromones, which are volatile in nature. Identification of nonvolatile pheromones have been relatively rare, especially in vertebrates. Male and female garter snakes use pheromones to mediate sexual behavior. The female sex attractiveness pheromone of the Canadian red-sided garter snake, Thamnophis sirtalis parietalis, consists of a novel series of nonvolatile saturated and monounsaturated long-chain methyl ketones, whereas the male sex recognition pheromone contains squalene. These compounds were isolated, identified, and partially synthesized, and field tests show them to be biologically active.

Prevention of antibiotic-associated diarrhea by Saccharomyces boulardii: a prospective study.

Saccharomyces boulardii, a nonpathogenic yeast, has been widely used in Europe to prevent antibiotic-associated diarrhea (AAD). We performed a prospective double-blind controlled study to investigate AAD in hospitalized patients and to evaluate the effect of S. boulardii, a living yeast, given in capsule form concurrently with antibiotics. Over 23 mo, 180 patients completed the study. Of the patients receiving placebo, 22% experienced diarrhea compared with 9.5% of patients receiving S. boulardii (p = 0.038). Risk factors found to be associated with AAD were multiple antibiotic combinations (containing clindamycin, cephalosporins, or trimethoprim-sulfamethoxazole) and tube feeding. Clostridium difficile, an anaerobe found in the stools of most patients with pseudomembranous colitis, was variably associated with AAD. We evaluated the role of C. difficile in AAD in the study population and found no significant association between the presence of C. difficile or cytotoxin with AAD. Approximately 33% of the patients without diarrhea harbored at least one C. difficile-positive stool and nearly 50% of these patients had detectable cytotoxin. Similar values were obtained in patients with diarrhea. Of C. difficile-positive patients, 31% (5/16) on placebo developed diarrhea compared with 9.4% (3/32) on S. boulardii; this difference was not statistically significant (p = 0.07). There were no discernable adverse effects of yeast administration. We conclude that S. boulardii reduces the incidence of antibiotic-associated diarrhea in hospitalized patients.

Paraneoplastic visceral neuropathy as a cause of severe gastrointestinal motor dysfunction.

The purpose of this study was to define the cause of severe gastrointestinal motor dysfunction in 7 patients with lung cancer. Six patients had small cell carcinoma and 1 patient had pulmonary carcinoid. Their ages ranged from 58 to 74 yr. All had intestinal pseudoobstruction and obstipation/constipation; 6 of 7 patients had gastroparesis; 4 of 4 patients had esophageal peristaltic abnormalities; and 2 patients had neurogenic bladders, autonomic insufficiency, and peripheral neuropathy. Five of 7 patients had dilated small bowel with 4 of them showing slow transit of barium; 2 of 7 patients had dilated colons; and 3 of 7 patients had slow colonic transit. Five patients died 4-9 mo after onset of gastrointestinal symptoms, and 2 survived. Post-mortem or surgical samples of the esophagus, stomach, small bowel, and colon showed neuron and axon degeneration and dropout, lymphoplasmacytic infiltration, and glial cell proliferation within the myenteric plexus of 6 patients. The antrum from the seventh patient had inflammatory cells within the myenteric plexus but without neuron dropout. Neuron numbers were significantly less than normal in each area of the gastrointestinal tract. Thus, we conclude that lung cancer may be complicated by severe gastrointestinal motor dysfunction resulting from visceral neuropathy of the myenteric plexus, a paraneoplastic effect of the cancer.

Studies on the stability of vinblastine sulfate in aqueous solution.

A stability study on vinblastine sulfate (1) in aqueous solution at several different temperatures (in the absence of light) has been undertaken. High-performance liquid chromatography was used to obtain kinetic data for the loss of vinblastine and to monitor the order of appearance of degradation products, of which eight were observed. The two most prominent components of early heat degradation have been tentatively identified by mass spectrometry (DCl), as a C19'-oxidation product (19'-oxovinblastine, 4, MH+ 825) and an isomer of vinblastine (MH+ 811). Products appearing later in the course of degradation include a component of MH+ 809, possibly corresponding to either 19'-hydroxy-3',4'-dehydrovinblastine (5) or 3',4'-dehydrovinblastine-6'-N-oxide (6), and three other products of MH+ 636, MH+ 670, and MH+ 795. In addition, optical rotation studies have established that racemization (with a possible reduction in biological activity) does not occur prior to transformation into degradation products. Preliminary experiments on light-mediated degradation demonstrated a different sequence of transformation, with the MH+ 670 and MH+ 795 products appearing first. Contrary to reports and suggestions in the literature and based on an estimated activation energy of 27.1 kcal/mol, the results of this study indicate that vinblastine sulfate is relatively stable in aqueous solution at or below room temperature (estimated t90 values: 150 d at 25 degrees C and 10.7 years at 5 degrees C) and has a t90 value of 16.6 d at 37 degrees C. These results are important in view of current interest in the continuous iv infusion of vinblastine sulfate.(ABSTRACT TRUNCATED AT 250 WORDS)

Sex and seasonal differences in the skin lipids of garter snakes.

1. This study investigates the skin lipids of male and female red-sided garter snakes both in the breeding season and in the non-breeding season. 2. Skin lipids were analyzed by means of thin-layer chromatography (TLC) and gas chromatography/mass spectrometry (GC/MS). 3. Distinct differences exist in the skin lipids of males and females. 4. Samples obtained during the breeding season were qualitatively different from those acquired during the non-breeding season.