First Transcriptome Analysis of Hepatoblastoma in Brazil: Unraveling the Pivotal Role of Noncoding RNAs and Metabolic Pathways

Hepatoblastoma stands as the most prevalent liver cancer in the pediatric population. Characterized by a low mutational burden, chromosomal and epigenetic alterations are key drivers of its tumorigenesis. Transcriptome analysis is a powerful tool for unraveling the molecular intricacies of hepatoblastoma, shedding light on the effects of genetic and epigenetic changes on gene expression. In this study conducted in Brazilian patients, an in-depth whole transcriptome analysis was performed on 14 primary hepatoblastomas, compared to control liver tissues. The analysis unveiled 1,492 differentially expressed genes (1,031 upregulated and 461 downregulated), including 920 protein-coding genes (62%). Upregulated biological processes were linked to cell differentiation, signaling, morphogenesis, and development, involving known hepatoblastoma-associated genes (DLK1, MEG3, HDAC2, TET1, HMGA2, DKK1, DKK4), alongside with novel findings (GYNG4, CDH3, and TNFRSF19). Downregulated processes predominantly centered around oxidation and metabolism, affecting amines, nicotinamides, and lipids, featuring novel discoveries like the repression of SYT7, TTC36, THRSP, CCND1, GCK and CAMK2B. Two genes, which displayed a concordant pattern of DNA methylation alteration in their promoter regions and dysregulation in the transcriptome, were further validated by RT-qPCR: the upregulated TNFRSF19, a key gene in the embryonic development, and the repressed THRSP, connected to lipid metabolism. Furthermore, based on protein-protein interaction analysis, we identified genes holding central positions in the network, such as HDAC2, CCND1, GCK, and CAMK2B, among others, that emerged as prime candidates warranting functional validation in future studies. Notably, a significant dysregulation of non-coding RNAs (ncRNAs), predominantly upregulated transcripts, was observed, with 42% of the top 50 highly expressed genes being ncRNAs. An integrative miRNA-mRNA analysis revealed crucial biological processes associated with metabolism, oxidation reactions of lipids and carbohydrates, and methylation-dependent chromatin silencing. In particular, four upregulated miRNAs (miR-186, miR-214, miR-377, and miR-494) played a pivotal role in the network, potentially targeting multiple protein-coding transcripts, including CCND1 and CAMK2B. In summary, our transcriptome analysis highlighted disrupted embryonic development as well as metabolic pathways, particularly those involving lipids, emphasizing the emerging role of ncRNAs as epigenetic regulators in hepatoblastomas. These findings provide insights into the complexity of the hepatoblastoma transcriptome and identify potential targets for future therapeutic interventions.

Unraveling the Genetic Architecture of Hepatoblastoma Risk: Birth Defects and Increased Burden of Germline Damaging Variants in Gastrointestinal/Renal Cancer Predisposition and DNA Repair Genes

The ultrarare hepatoblastoma (HB) is the most common pediatric liver cancer. HB risk is related to a few rare syndromes, and the molecular bases remain elusive for most cases. We investigated the burden of rare damaging germline variants in 30 Brazilian patients with HB and the presence of additional clinical signs. A high frequency of prematurity (20%) and birth defects (37%), especially craniofacial (17%, including craniosynostosis) and kidney (7%) anomalies, was observed. Putative pathogenic or likely pathogenic monoallelic germline variants mapped to 10 cancer predisposition genes (CPGs: APC, CHEK2, DROSHA, ERCC5, FAH, MSH2, MUTYH, RPS19, TGFBR2 and VHL) were detected in 33% of the patients, only 40% of them with a family history of cancer. These findings showed a predominance of CPGs with a known link to gastrointestinal/colorectal and renal cancer risk. A remarkable feature was an enrichment of rare damaging variants affecting different classes of DNA repair genes, particularly those known as Fanconi anemia genes. Moreover, several potentially deleterious variants mapped to genes impacting liver functions were disclosed. To our knowledge, this is the largest assessment of rare germline variants in HB patients to date, contributing to elucidate the genetic architecture of HB risk.

Hepatoblastomas exhibit marked NNMT downregulation driven by promoter DNA hypermethylation

Hepatoblastomas exhibit the lowest mutational burden among pediatric tumors. We previously showed that epigenetic disruption is crucial for hepatoblastoma carcinogenesis. Our data revealed hypermethylation of nicotinamide N-methyltransferase, a highly expressed gene in adipocytes and hepatocytes. The expression pattern and the role of nicotinamide N-methyltransferase in pediatric liver tumors have not yet been explored, and this study aimed to evaluate the effect of nicotinamide N-methyltransferase hypermethylation in hepatoblastomas. We evaluated 45 hepatoblastomas and 26 non-tumoral liver samples. We examined in hepatoblastomas if the observed nicotinamide N-methyltransferase promoter hypermethylation could lead to dysregulation of expression by measuring mRNA and protein levels by real-time quantitative polymerase chain reaction, immunohistochemistry, and Western blot assays. The potential impact of nicotinamide N-methyltransferase changes was evaluated on the metabolic profile by high-resolution magic angle spinning nuclear magnetic resonance spectroscopy. Significant nicotinamide N-methyltransferase downregulation was revealed in hepatoblastomas, with two orders of magnitude lower nicotinamide N-methyltransferase expression in tumor samples and hepatoblastoma cell lines than in hepatocellular carcinoma cell lines. A specific TSS1500 CpG site (cg02094283) of nicotinamide N-methyltransferase was hypermethylated in tumors, with an inverse correlation between its methylation level and nicotinamide N-methyltransferase expression. A marked global reduction of the nicotinamide N-methyltransferase protein was validated in tumors, with strong correlation between gene and protein expression. Of note, higher nicotinamide N-methyltransferase expression was statistically associated with late hepatoblastoma diagnosis, a known clinical variable of worse prognosis. In addition, untargeted metabolomics analysis detected aberrant lipid metabolism in hepatoblastomas. Data presented here showed the first evidence that nicotinamide N-methyltransferase reduction occurs in hepatoblastomas, providing further support that the nicotinamide N-methyltransferase downregulation is a wide phenomenon in liver cancer. Furthermore, this study unraveled the role of DNA methylation in the regulation of nicotinamide N-methyltransferase expression in hepatoblastomas, in addition to evaluate the potential effect of nicotinamide N-methyltransferase reduction in the metabolism of these tumors. These preliminary findings also suggested that nicotinamide N-methyltransferase level may be a potential prognostic biomarker for hepatoblastoma.

Dynamics in the Plastic Crystalline Phases of Cyclohexanol and Cyclooctanol Studied by Quasielastic Neutron Scattering

Plastic crystals are a promising candidate for solid state ionic conductors. In this work, quasielastic neutron scattering is employed to investigate the center of mass diffusive motions in two types of plastic crystalline cyclic alcohols: cyclohexanol and cyclooctanol. Two separate motions are observed which are attributed to long-range translational diffusion (α-process) and cage rattling (fast β-process). Residence times and diffusion coefficients are calculated for both processes, along with the confinement distances for the cage rattling. In addition, a binary mixture of these two materials is measured to understand how the dynamics change when a second type of molecule is added to the matrix. It is observed that, upon the addition of the larger cyclooctanol molecules into the cyclohexanol solution, the cage size decreases, which causes a decrease in the observed diffusion rates for both the α- and fast β-processes.

Evaluation of attenuation correction in cardiac PET using PET/MR

BACKGROUND

Simultaneous acquisition Positron emission tomography/magnetic resonance (PET/MR) is a new technology that has potential as a tool both in research and clinical diagnosis. However, cardiac PET acquisition has not yet been validated using MR imaging for attenuation correction (AC). The goal of this study is to evaluate the feasibility of PET imaging using a standard 2-point Dixon volume interpolated breathhold examination (VIBE) MR sequence for AC.

METHODS AND RESULTS

Evaluation was performed in both phantom and patient data. A chest phantom containing heart, lungs, and a lesion insert was scanned by both PET/MR and PET/CT. In addition, 30 patients underwent whole-body 18F-fluorodeoxyglucose PET/CT followed by simultaneous cardiac PET/MR. Phantom study showed 3% reduction of activity values in the myocardium due to the non-inclusion of the phased array coil in the AC. In patient scans, average standardized uptake values (SUVs) obtained by PET/CT and PET/MR showed no significant difference (n = 30, 4.6 ± 3.5 vs 4.7 ± 2.8, P = 0.47). There was excellent per patient correlation between the values acquired by PET/CT and PET/MR (R 2 = 0.97).

CONCLUSIONS

Myocardial SUVs PET imaging using MR for AC shows excellent correlation with myocardial SUVs obtained by standard PET/CT imaging. The 2-point Dixon VIBE MR technique can be used for AC in simultaneous PET/MR data acquisition.

Effect of adding nanometre-sized heterogeneities on the structural dynamics and the excess wing of a molecular glass former

We present the relaxation dynamics of glass-forming glycerol mixed with 1.1 nm sized polyhedral oligomeric silsesquioxane (POSS) molecules using dielectric spectroscopy (DS) and two different neutron scattering (NS) techniques. Both, the reorientational dynamics as measured by DS and the density fluctuations detected by NS reveal a broadening of the α relaxation when POSS molecules are added. Moreover, we find a significant slowing down of the α-relaxation time. These effects are in accord with the heterogeneity scenario considered for the dynamics of glasses and supercooled liquids. The addition of POSS also affects the excess wing in glycerol arising from a secondary relaxation process, which seems to exhibit a dramatic increase in relative strength compared to the α relaxation.

Development of equipments for determination of BNCT source spectral parameters

The knowledge of neutron and gamma ray energy spectra can strongly influence the BNCT information about delivered dose to target volume as well as to the surface healthy tissue region. This region is very often decisive to stay within the recommended healthy tissue limit. Modification of neutron Bonner spectrometer to one block i.e. Bonner spectrometer monoblock (BSM) and gamma ray Si semiconductor spectrometer are being developed and verified in real conditions of LVR-15 reactor beam. Test measurements were also carried out in conditions of known standard spectra. The accepted procedure and the first results documenting the sensitivity BSM to different spectra are presented.

Variações anatômicas do ramo tenar do nervo mediano no túnel do carpo

Lanz, em 1977, classificou as possíveis variações do ramo motor no nervo mediano em relação ao ligamento transverso do carpo. Baseado nesse trabalho, foi proposto um estudo realizado em cadáveres para observar as possíveis variações da anatomia do ramo motor do nervo mediano. Foram utilizadas 44 peças anatômicas de membros superiores conservadas em formol. Foram dissecadas, cuidadosamente, a emergência e a entrada do ramo tenar na musuclatura, observando o número de ramos, a região da emergência e o tipo de trajeto, de acordo com a classificação de Lanz. A variação mais encontrada foi a anormalidades no trajeto do ramo tenar do nervo mediano, sendo a maior parte do tipo extra-ligamentar. A maior parte das peças anatômicas possuía apenas um ramo tenar do nervo mediano.

Assessing plasma pharmacokinetics of cholesterol following oral coadministration with a novel vegetable stanol mixture to fasting rats

The purpose of this project was to assess the plasma pharmacokinetics of [(3)H]cholesterol following coadministration of a novel vegetable stanol mixture composed of sitostanol and campestanol (FCP-3P4) to fasting rats. Following an overnight fast (12-16 h) and 48 h post-surgery, adult male Sprague Dawley rats were divided into six treatment groups and received a single-dose oral gavage at 0700 h of either: [(3)H]cholesterol (25 microCi/mL), FCP-3P4 (5 mg/kg) + [(3)H]cholesterol (25 microCi/mL), FCP-3P4 (12.5 mg/kg) + [(3)H]cholesterol (25 microCi/mL), FCP-3P4 (25 mg/kg) + [(3)H]cholesterol (25 microCi/mL), FCP-3P4 (50 mg/kg) + [(3)H]cholesterol (25 microCi/mL), or FCP-3P4 (100 mg/kg) + [(3)H]cholesterol (25 microCi/mL). Intralipid (10%) was the vehicle used to solubilize and coadminister [(3)H]cholesterol and FCP-3P4. Liquid chromatography-mass spectrometry analysis confirmed minimal cholesterol and vegetable stanol content within 10% Intralipid. Analysis of plasma pharmacokinetics was initiated by sampling 0.5 mL of blood prior to and 0.25, 0.5 1.0, 2.0, 4.0, 6.0, 8.0, 10, 24, 28, 32, and 48 h post-oral gavage. Plasma samples were obtained by centrifugation of the blood samples and analyzed for [(3)H]cholesterol radioactivity. Pharmacokinetics analysis was performed by standard noncompartmental methods using statistical moment theory. Thin-layer chromatography was used to confirm that the majority of radioactivity measured in plasma was cholesterol (in the form of esterified or unesterified cholesterol). Greater than 90% of the radioactivity measured in all plasma samples was cholesterol-associated (in the form of either esterified or unesterified cholesterol). The coadministration of FCP-3P4 significantly decreased the area under the curve of [(3)H]cholesterol concentration versus time from 0 to 48 h (AUC(0-48h)) and maximum concentration (C(max)) in a dose-dependent manner. However, coadministration of FCP-3P4 at 25, 50, and 100 mg/kg resulted in a significant increase in apparent total body clearance (CL/F, where F is the bioavailability constant), apparent volume of distribution (V(d)/F), and oral absorption rate constant (k(a)) of [(3)H]cholesterol compared with controls. These findings suggest that the novel vegetable stanol mixture, FCP-3P4, modifies the plasma pharmacokinetics of [(3)H]cholesterol in fasting rats on oral coadministration.

Identification and detection of Trypanosoma cruzi by using a DNA amplification fingerprint obtained from the ribosomal intergenic spacer

We designed a PCR assay targeted on repeated elements of the ribosomal intergenic spacer which produces highly polymorphic DNA band patterns for different strains of Trypanosoma cruzi. By labeling the PCR products with digoxigenin and by chemiluminescence detection, we improved the assay sensitivity by three orders of magnitude to get T. cruzi strain fingerprints in feces of the trypanosome-infected triatomine bug vector. We also developed a capture assay for the digoxigenin-labeled PCR products that allowed us to detect T. cruzi in triatomine bug vector feces and in human serum samples with a solid support.

[A comparative study of the structural state of skeletal muscle and smooth muscle fiber tropomyosin in ghost skeletal muscle fibers by a fluorescent probe method]

The structural state of skeletal muscle and smooth muscle fiber tropomyosins in ghost fibers of skeletal muscles has been studied by means of polarization microfluorimetry. Tropomyosins and F-actin of ghost fibers were labelled with N-(iodoacetyl)-N-(1-naphthyl-5-sulfo)-ethylenediamine (1,5-IA-EDANS) or the phalloidin-rhodamine complex, respectively. It has been found that skeletal tropomyosin bound to ghost muscle fibers is more flexible in comparison with smooth muscle tropomyosin. The flexibility of the thin filaments of the ghost fibers labelled in F-actin by the phalloidin-rhodamine complex and containing smooth muscle tropomyosin is higher than that of the thin filaments containing the bound skeletal muscle protein.

Orally administered cefpodoxime proxetil for treatment of uncomplicated gonococcal urethritis in males: a dose-response study

An open-label, dose-response study of cefpodoxime proxetil (CPD), an expanded-spectrum cephalosporin, was conducted with 58 males with uncomplicated Neisseria gonorrhoeae infections with single doses of 600, 400, 200, 100, or 50 mg of CPD administered orally by tablet. CPD eradicated N. gonorrhoeae in all 50 evaluable patients (10 per group) at all doses studied. Eight of the isolates eradicated were beta-lactamase-producing organisms. Two patients reported three side effects, nausea, vomiting, and diarrhea, which were mild and resolved without intervention or sequelae. There were no clinically remarkable drug-related changes in vital signs or clinical laboratory assays. Results show that single oral doses of CPD are an effective and well-tolerated treatment for uncomplicated N. gonorrhoeae infection in males at doses as low as 50 mg.

Pharmacokinetics of trospectomycin sulphate in healthy subjects after single intravenous and intramuscular doses

The pharmacokinetics of trospectomycin (75-1000 mg free base equivalents) were studied in 128 healthy males (eight per dose group), after a 20 min intravenous (i.v.) infusion and intramuscular (i.m.) injection of trospectomycin sulphate. The concentrations of trospectomycin in serum were described by bi- or tri-exponential disposition functions indicating an initial half-life of 1.1-1.4 h for the i.v. dose and 1.6-2.1 h for the i.m. dose and terminal half-lives of over 15 h. Most of the drug was eliminated rapidly (mean residence time 5-12 h). The distribution volume was 59-112% of body weight and clearance was 112-152 ml min-1. The absorption into blood after i.m. dosing was rapid. The area under the concentration-time curve and maximum concentration values were linearly related to dose. Serum drug concentrations fell below the minimum inhibitory concentration values for a variety of organisms by 8-12 h, which indicates that two or three times daily dosing would be appropriate. However, the long terminal half-life suggests that significant accumulation is likely in some tissues with an 8 h dose interval and this may prolong the action of trospectomycin.

Human safety and pharmacokinetics of a single intramuscular dose of a novel spectinomycin analog, trospectomycin (U-63,366F)

In this study, local and systemic tolerance and pharmacokinetics of trospectomycin sulfate in human beings were evaluated for the first time. Trospectomycin sulfate (U-63,366F; trospectomycin) or sterile saline was administered to 96 healthy male volunteers in doses ranging from 0.25 ml (75 mg) to 3.3 ml (1,000 mg) in a single intramuscular injection in a double-blind, randomized design. Volunteers were screened to establish baseline vital signs and laboratory test values. Pain and tenderness at the injection site, which occurred at doses of 450 mg and above, were the most common side effects; they were mild in severity and transient. Adverse drug experiences reported by subjects included nausea, dizziness, light-headedness, diaphoresis, costal pain, and perioral numbness. The perioral numbness (paresthesia) experienced at doses of 750, 900, and 1,000 mg was probably drug related. No Clostridium difficile toxin was detected in fecal samples. Pharmacokinetic calculations based on data obtained by high-performance liquid chromatography showed that after a 1,000-mg intramuscular dose of trospectomycin (3.3 ml), the serum mean half-life was 1.85 h (1.70 to 2.02 h), mean area under the serum concentration-time curve was 140.2 micrograms.h/ml and was linear with dose, mean peak concentration was 28.3 micrograms/ml (20.4 to 34.7 micrograms/ml), mean time to maximum concentration was 71 min (30 to 120 min), and the elimination rate constant was 0.307 h-1. The elimination rate constant and half-life did not vary with dose. Little trospectomycin was detected in 2-day fecal collections. A few randomly occurring abnormal clinical laboratory test values and vital signs were observed. For the trospectomycin-treated group, creatinine phosphokinase increased substantially for 24 h after injection and then decrease through day 5, while serum glutamic oxalacetic transaminase and lactate dehydrogenase increased slightly.

Multiple-dose, double-blind, placebo controlled intravenous tolerance and pharmacokinetic study of trospectomycin sulfate (U-63, 366F) in healthy male volunteers

Trospectomycin sulfate is a novel aminocyclitol antibiotic. This study evaluated the tolerance and the pharmacokinetics of multiple, intravenous doses of trospectomycin (TRO) in healthy male volunteers. Three groups of 10 volunteers were studied. Eight volunteers in each group were studied in a parallel design to receive trospectomycin (Group 1 = 250 mg, Group 2 = 500 mg, Group 3 = 750 mg) while 2 volunteers received placebo (normal saline). Drug doses were administered in 30 ml volumes over 30 min every 8 h for 7 days (i.e. 21 total doses). Evaluations of vital signs, side effects, and safety laboratory tests were made at regular intervals during the study. The most frequent medical events observed in the volunteers receiving trospectomycin were perioral/facial paresthesias (54%), pain at the i.v. infusion site (46%), dizziness/lightheadedness (58%), and GI symptoms (38%). A statistically significant dose response relationship was observed for the incidence of perioral/facial paresthesias and pain at the i.v. infusion site (i.e., increased incidence with increased dose). All the medical events were mild or moderate in severity and reversible following drug discontinuation. In the 500 and 750 mg trospectomycin groups, standing systolic blood pressure decreased significantly with the first dose of study drug. Elevated levels of SGPT were observed in 9 volunteers (1 in placebo, 3 in 250 mg, 1 in 500 mg, and 4 in 750 mg dose groups). This study demonstrates that multiple intravenous trospectomycin doses up to 750 mg are reasonably well tolerated in healthy male volunteers. The concentration of trospectomycin in serum, measured with a sensitive HPLC assay, was less than 3 mcg/ml at 8 h postinfusion for all dose levels.(ABSTRACT TRUNCATED AT 250 WORDS)

[The effect of caldesmon and tropomyosin from smooth muscles on the motility of myosin head in ghost muscle fibers]

The effects of caldesmon and smooth muscle tropomyosin on the motility of myosin subfragment I (SI) modified by N-(iodoacetyl)-N'-(1-naphtyl-5-sulfo)-ethylenediamine (1.5-IAEDANS) was studied in myosin-, troponin- and tropomyosin-free rabbit ghost muscle fibers using the polarized microphotometry technique. It was found that the fluorescence anisotropy initiated by the 1.5-IAEDANS-SI arrangement in the fibers is higher in the presence of tropomyosin than in its absence. Caldesmon diminishes the fluorescence anisotropy of the fibers. Data from a kinetic analysis suggest that the motility of fluorophores in the presence of tropomyosin in thin filaments is markedly decreased. Caldesmon weakens the effect of tropomyosin on the fluorescent label motility. It was supposed that caldesmon and tropomyosin initiate conformational changes in myosin heads which are accompanied by loosening or strengthening of their bonds with F-actin, respectively. Caldesmon inhibits the effect induced by tropomyosin.

[Caldesmon and myosin subfragment-1 act differently on the structural state of 1,5-IAEDANS-modified tropomyosin in ghost muscle fibers]

The effect of caldesmon (CD) and subfragment 1 of myosin (S1) on the structural state of tropomyosin (TM) modified with N-(iodoacetyl)-N-(1-naphthyl-5-sulfo)-ethylene-diamine (1.5-IAEDANS) in single myosin-free skeletal muscle fibers was studied using polarized microfluorimetry. S1 was performed from skeletal muscles of rabbits, whereas CD and TM were prepared from the smooth muscle of chicken gizzards. An analysis of experimental data revealed that CD initiates and increases the motility of 1.5-IAEDANS-TM, while S1 decreases it. In the presence of CD S1 binding to actin is accompanied by significant changes in the fluorescent label motility. It is supposed that CD and S1 induce in TM conformational changes which interfere with the protein interaction with F-actin.

Safety and pharmacokinetics of intravenously administered trospectomycin sulfate

Local and systemic tolerance and drug pharmacokinetics were evaluated after a single intravenous infusion of 75 to 1,000 mg of trospectomycin or placebo in 96 healthy volunteers. No clinically significant changes, trends, or abnormalities were observed in the vital signs, electrocardiograms, or laboratory test results; however, there were some statistically significant dose effects or dose-by-time interactions on some of the measures. Mild, transient, local reactions at the infusion site were reported by 20% of the trospectomycin-treated and 22% of the placebo-treated subjects. No irritation of the surrounding tissue was noted when extravasation occurred. Mild, transient, perioral-facial numbness, which was probably drug-related, was the most commonly reported systemic adverse drug experience, occurring in 17 of 64 trospectomycin-treated subjects, but only at doses of 600 mg and above. Pharmacokinetic analyses showed that after a 1,000-mg intravenous dose of trospectomycin, the mean serum half-life was 2.18 hr, the mean area under the curve (AUC) was 157.0 hr x micrograms/ml, the mean maximum concentration (Cmax) was 82.4 micrograms/ml, the mean time to maximum concentration was 25.0 min, and the elimination rate (Ke) was 0.33 hr-1. The Ke and half-life did not vary with dose, and both Cmax and AUC showed a strong linear trend. From 48% to 62% of the dose was excreted in the urine during the first 48 hours after infusion. Under the conditions of this study, intravenous trospectomycin was well tolerated by human subjects at single doses up to and including 1,000 mg.

Disposition of cefmetazole in healthy volunteers and patients with impaired renal function

The disposition of cefmetazole was studied in 25 subjects with various degrees of renal function after a 1,000-mg, constant-rate, 30-min intravenous infusion of cefmetazole sodium. In six subjects with creatinine clearance (CLCR) of greater than 90 ml/min per 1.73 m2 (group 1), the terminal elimination half-life (t1/2 beta) was 1.31 +/- 0.54 h (mean +/- standard deviation), cefmetazole total body clearance (CLP) was 132.8 +/- 25.1 ml/min per 1.73 m2, and volume of distribution at steady state was 0.165 +/- 0.025 liter/kg. The fraction of dose excreted unchanged in the urine was 84.0% +/- 26.1%. Subjects with CLCRS of 40 to 69 (group 2, n = 6) and 10 to 39 (group 3, n = 6) ml/min per 1.73 m2 demonstrated prolongation of the t1/2 beta (3.62 +/- 1.06 and 5.93 +/- 1.81 h, respectively) and significant reductions in cefmetazole CLP (52.8 +/- 14.3 and 30.2 +/- 10.2 ml/min per 1.73 m2, respectively), compared with group 1. In seven subjects on chronic hemodialysis (group 4) studied during an interdialytic period, the cefmetazole t1/2 beta was increased to 24.10 +/- 8.12 h and the CLP was reduced to 6.8 +/- 2.1 ml/min per 1.73 m2. Cefmetazole CLP correlated positively with CLCR (r = 0.951, P less than 0.001): CLP = (1.181 . CLCR) -- 0.287. The disposition of cefmetazole was also assessed in six group 4 subjects during an intradialytic period. The t1/2 beta during hemodialysis (2.09 +/- 0.69 h) was significantly shorter than that observed during the interdialytic period. The hemodialysis clearance of cefmetazole was 86.1 +/- 20.1 ml/min, and the fraction of cefmetazole removed during hemodialysis was 59.8% +/- 5.9%. It is recommended that patients with renal insufficiency received standard doses of cefmetazole at extended intervals and patients on maintenance hemodialysis received standard doses after hemodialysis.

von Willebrand's variant (type II Buffalo). Thrombocytopenia after desmopressin but absence of in vitro hypersensitivity to ristocetin

Von Willebrand's disease is categorized into types and subtypes based on multimeric analysis of plasma von Willebrand's factor. Such categorization is of value because both the mode of inheritance and the choice of therapeutic material differ between subtypes. The Type IIB variant is characterized by hypersensitivity in vitro to ristocetin and thrombocytopenia after administration of desmopressin (DDAVP). Hypersensitivity to ristocetin has also been described in Type I variants but without thrombocytopenia after DDAVP. This report describes a new Type II variant characterized by the converse situation, absence of hypersensitivity to ristocetin in vitro but transient thrombocytopenia after intravenous administration of DDAVP.

Clinical experience with cefmetazole sodium in the United States: an overview

The clinical development programme for cefmetazole sodium included over 4000 patients treated by 78 investigators. Cefmetazole therapy was compared with that of cefoxitin sodium (cefoxitin) for the treatment of urinary tract, skin and soft tissue, lower respiratory, abdominal, and gynaecological infections (with cefoxitin-sensitive pathogens) and for the prevention of postoperative wound infection in patients undergoing surgical procedures. Both cefmetazole and cefoxitin were administered intravenously in all studies. Cefmetazole was as effective as cefoxitin in the treatment of the infections studied. In the surgical wound infection prophylaxis studies, multiple-dose cefmetazole therapy was more effective than multiple-dose cefoxitin therapy in patients undergoing lower gastrointestinal surgery; this difference approached statistical significance. Both multiple-dose and single-dose cefmetazole therapy were as effective as multiple-dose cefoxitin treatment in the other types of surgery studied. Clinical laboratory findings and adverse medical events reported among cefmetazole patients were similar to those observed in patients treated with cefoxitin.

Pharmacokinetics of single-dose cefmetazole following intramuscular administration of cefmetazole sodium to healthy male volunteers

The tolerance and pharmacokinetics of cefmetazole were studied in healthy male volunteers who received a placebo (sterile saline) or a single dose of cefmetazole sodium intramuscularly. Drug-treated volunteers received one of four doses, 0.375, 0.750, 1, or 2 g. The drug was well tolerated, with no adverse medical events or laboratory changes observed during the study that could affect the pharmacokinetic interpretation of the data. Cefmetazole concentrations were determined by using a specific high-performance liquid chromatographic method. Serum cefmetazole concentrations were well described by a one-compartment open model with first-order absorption and elimination. Cefmetazole was rapidly absorbed in most volunteers, with a mean time to maximum concentration in serum of 1.24 +/- 0.12 h (+/- standard error of the mean), and the mean maximum concentration in serum increased from 17.0 +/- 1.6 to 74.2 +/- 9.5 micrograms/ml over the 0.375- to 2-g dose range. Maximum concentrations in serum, areas under serum concentration-time curve, and urinary excretion of intact drug increased in proportion to cefmetazole sodium dose. Times at which maximum concentrations in serum occurred, apparent volumes of distribution, steady-state volumes of distribution, absorption and elimination half-lives, and systemic clearances did not change significantly (P greater than 0.05) with drug dose. Although absorption and elimination half-lives were not significantly different in 10 of 40 volunteers (P greater than 0.05), in a majority of subjects elimination half-lives were approximately 10 times longer than absorption half-lives. The mean recovery of intact drug in urine ranged from 68.8 to 86.0% over the dose range studied, with a mean recovery over all doses of 77.1 +/- 2.4%. Rental clearances were significantly lower (P < 0.05) for the two lowest doses (93.0 and 84.3 versus 115.0 and 118.0 ml/min); these differences are not considered clinically important. The results of this study indicate that cefmetazole pharmacokinetics are linear after administration of single intramuscular doses ranging from 0.375 to 2 g, that clinically relevant concentrations of cefmetazole in serum (1 to 2 micrograms/ml) persist in a majority of volunteers for more than 8 h after administration of 0.750-g or higher doses, and that clinically relevant concentrations of cefmetazole continue to be excreted in urine 8 to 12 h after administration of 0.375- to 2-g doses.