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While pulsed field gradient stimulated echo nuclear magnetic resonance (PFGSTE NMR) spectroscopy has found widespread use in the quantification of self-diffusivity for many NMR-active nuclei, extending this technique to uncommon nuclei with unfavorable NMR properties remains an active area of research. Potassium-39 ( 39 K) is an archetypical NMR nucleus exhibiting an unfavorable gyromagnetic ratio combined with a very low Larmor frequency. Despite these unfavorable properties, this work demonstrates that 39 K PFGSTE NMR experiments are possible in aqueous solutions of concentrated potassium nitrite. Analysis of the results indicates that 39 K NMR diffusometry is feasible when the nuclei exhibit spin-lattice and spin-spin relaxation coefficients on the order of 60-100 ms and 50-100 ms, respectively. The diffusivity of 39 K followed Arrhenius behavior, and comparative 23 Na, 7 Li, and 1 H PFGSTE NMR studies of equimolal sodium nitrite and lithium nitrite solutions led to correlations between the enthalpy of hydration with the activation energy governing self-diffusion of the cations and also of water. Realizing the feasibility of 39 K PFGSTE NMR spectroscopy has a widespread impact across energy sciences because potassium is a common alkali element in energy storage materials and other applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

A simple and adaptable process for the production of porous PEEK has been demonstrated herein, which uses compression moulding to infiltrate molten PEEK into of a packed bed of salt beads. The process has the capacity to vary the pore size and porosity within the range suitable for materials to replace bone, but compressive testing showed the stiffness to be well below the target to match trabecular bone. This issue was addressed by creating a hybrid structure, integrating "pillars" of solid PEEK into the porous structure, by the injection over-moulding of compression moulded PEEK-salt inserts that contained drilled holes. Good bonding between the moulding and the insert was demonstrated and it was found that as little as 35 mm 2 of support, in the form of PEEK "pillars" was required to achieve the target performance., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Orthobiologics is a rapidly advancing field utilising cell-based therapies and biomaterials to enable the body to repair and regenerate musculoskeletal tissues. This paper reports on a cost-effective flame spheroidisation process for production of novel porous glass microspheres from calcium phosphate-based glasses to encapsulate and deliver stem cells. Careful selection of the glass and pore-forming agent, along with a manufacturing method with the required processing window enabled the production of porous glass microspheres via a single-stage manufacturing process. The morphological and physical characterisation revealed porous microspheres with tailored surface and interconnected porosity (up to 76 ± 5%) with average pore size of 55 ± 8 µm and surface areas ranging from 0.34 to 0.9 m 2  g -1 . Furthermore, simple alteration of the processing parameters produced microspheres with alternate unique morphologies, such as with solid cores and surface porosity only. The tuneable porosity enabled control over their surface area, degradation profiles and hence ion release rates. Furthermore, cytocompatibility of the microspheres was assessed using human mesenchymal stem cells via direct cell culture experiments and analysis confirmed that they had migrated to within the centre of the microspheres. The novel microspheres developed have huge potential for tissue engineering and regenerative medicine applications., Statement of Significance: This manuscript highlights a simple cost-effective one-step process for manufacturing porous calcium phosphate-based glass microspheres with varying control over surface pores and fully interconnected porosity via a flame spheroidisation process. Moreover, a simple alteration of the processing parameters can produce microspheres which have a solid core with surface pores only. The tuneable porosity enabled control over their surface area, degradation profiles and hence ion release rates. The paper also shows that stem cells not only attach and proliferate but more importantly migrate to within the core of the porous microspheres, highlighting applications for bone tissue engineering and regenerative medicine., (Copyright © 2018. Published by Elsevier Ltd.)

Neutron diffraction, 23 Na and 31 P NMR, and FTIR spectroscopy have been used to investigate the structural effects of substituting CaO with SrO in a 40P 2 O 5 ·(16-x)CaO·20Na 2 O·24MgO·xSrO glass, where x is 0, 4, 8, 12 and 16mol%. The 31 P solid-state NMR results showed similar amounts of Q 1 and Q 2 units for all of the multicomponent glasses investigated, showing that the substitution of Sr for Ca has no effect on the phosphate network. The M-O coordinations (M=Mg, Ca, Sr, Na) were determined for binary alkali and alkaline earth metaphosphates using neutron diffraction and broad asymmetric distributions of bond length were observed, with coordination numbers that were smaller and bond lengths that were shorter than in corresponding crystals. The Mg-O coordination number was determined most reliably as 5.0(2). The neutron diffraction results for the multicomponent glasses are consistent with a structural model in which the coordination of Ca, Sr and Na is the same as in the binary metaphosphate glass, whereas there is a definite shift of Mg-O bonds to longer distance. There is also a small but consistent increase in the Mg-O coordination number and the width of the distribution of Mg-O bond lengths, as Sr substitutes for Ca. Functional properties, including glass transition temperatures, thermal processing windows, dissolution rates and ion release profiles were also investigated. Dissolution studies showed a decrease in dissolution rate with initial addition of 4mol% SrO, but further addition of SrO showed little change. The ion release profiles followed a similar trend to the observed dissolution rates. The limited changes in structure and dissolution rates observed for substitution of Ca with Sr in these fixed 40mol% P 2 O 5 glasses were attributed to their similarities in terms of ionic size and charge., Statement of Significance: Phosphate based glasses are extremely well suited for the delivery of therapeutic ions in biomedical applications, and in particular strontium plays an important role in the treatment of osteoporosis. We show firstly that the substitution of strontium for calcium in bioactive phosphate glasses can be used to control the dissolution rate of the glass, and hence the rate at which therapeutic ions are delivered. We then go on to examine in detail the influence of Sr/Ca substitution on the atomic sites in the glass, using advanced structural probes, especially neutron diffraction. The environments of most cations in the glass are unaffected by the substitution, with the exception of Mg, which becomes more disordered., (Copyright © 2017 Acta Materialia Inc. All rights reserved.)

Porous Ti with open porosity in the range of 70-80% has been made using Ti powder and a particulate leaching technique using porous, spherical, NaCl beads. By incorporating the Ti powder into a pre-existing network of salt beads, by tapping followed by compaction, salt dissolution and "sintering", porous structures with uniform density, pore and strut sizes and a predictable level of connectivity have been produced, showing a significant improvement on the structures made by conventional powder mixing processes. Parts made using beads with sizes in the range of 0.5-1.0 mm show excellent promise as porous metals for medical devices, showing structures and porosities similar to those of commercial porous metals used in this sector, with inter-pore connections that are similar to trabecular bone. The elastic modulus (0.86 GPa) is lower than those for commercial porous metals and more closely matches that of trabecular bone and good compressive yield strength is retained (21 MPa). The ability to further tailor the structure, in terms of the density and the size of the pores and interconnections has also been demonstrated by immersion of the porous components in acid., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Porous PEEK structures with approximately 85% open porosity have been made using PEEK-OPTIMA® powder and a particulate leaching technique using porous, near-spherical, sodium chloride beads. A novel manufacturing approach is presented and compared with a traditional dry mixing method. Irrespective of the method used, the use of near-spherical beads with a fairly narrow size range results in uniform pore structures. However the integration, by tapping, of fine PEEK into a pre-existing network salt beads, followed by compaction and "sintering", produces porous structures with excellent repeatability and homogeneity of density; more uniform pore and strut sizes; an improved and predictable level of connectivity via the formation of "windows" between the cells; faster salt removal rates and lower levels of residual salt. Although tapped samples show a compressive yield stress >1 MPa and stiffness >30 MPa for samples with 84% porosity, the presence of windows in the cell walls means that tapped structures show lower strengths and lower stiffnesses than equivalent structures made by mixing., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Animal models are frequently used to assist in the determination of the long- and short-term effects of space flight. The space environment, including microgravity, can impact many physiological and immunological system parameters. It has been found that ground based models of microgravity produce changes in white blood cell counts, which negatively affects immunologic function. As part of the Center of Acute Radiation Research (CARR), we compared the acute effects on white blood cell parameters induced by the more traditionally used animal model of hindlimb unloading (HU) with a recently developed reduced weightbearing analog known as partial weight suspension (PWS). Female ICR mice were either hindlimb unloaded or placed in the PWS system at 16% quadrupedal weightbearing for 4 h, 1, 2, 7 or 10 days, at which point complete blood counts were obtained. Control animals (jacketed and non-jacketed) were exposed to identical conditions without reduced weightbearing. Results indicate that significant changes in total white blood cell (WBC), neutrophil, lymphocyte, monocyte and eosinophil counts were observed within the first 2 days of exposure to each system. These differences in blood cell counts normalized by day 7 in both systems. The results of these studies indicate that there are some statistically significant changes observed in the blood cell counts for animals exposed to both the PWS and HU simulated microgravity systems.

Background: The hypothalamic neuropeptide melanin-concentrating hormone (MCH) plays a critical role in energy homeostasis. Abundant expression of the MCH receptor is observed outside the hypothalamus, especially in the dorsal and the ventral striatum, raising the possibility that MCH modulates the function of the midbrain dopamine neurons and associated circuitry., Methods: The MCH receptor 1 (MCHR1) expression was assessed by in situ hybridization. Expression of dopamine transporter (DAT) and the dopamine D1 and D2 receptor (D1R and D2R) subtypes in the caudate-putamen (CPu) and the nucleus accumbens (Acb) was evaluated by immunoblotting. Amperometry in ex vivo slices of the Acb was used to measure evoked-dopamine release in MCH-/ - mice. Catalepsy in MCH+/+ and MCH-/- mice was assessed by the bar test after haloperidol injection. Locomotor activity was measured after acute and chronic treatment with amphetamine and after dopamine reuptake inhibitor GBR 12909 administration., Results: The psychostimulant amphetamine caused enhanced behavioral sensitization in MCH-/- mice. We found significantly elevated expression of the DAT in the Acb of MCH-/- mice. The DAT-mediated uptake of dopamine was also enhanced in MCH-/- mice consistent with increased expression of DAT. We also found that evoked dopamine release is significantly increased in the Acb shell of MCH-/- mice. The GBR 12909 administration increased the locomotor activity of MCH-/- mice significantly above that of MCH+/+ mice., Conclusions: These results demonstrate that MCH, in addition to its known role in feeding and weight regulation, plays a critical role in regulating Acb dopamine signaling and related behavioral responses.

An automated parallel crystallisation search for physical forms of carbamazepine, covering 66 solvents and five crystallisation protocols, identified three anhydrous polymorphs (forms I-III), one hydrate and eight organic solvates, including the single-crystal structures of three previously unreported solvates (N,N-dimethylformamide (1:1); hemi-furfural; hemi-1,4-dioxane). Correlation of physical form outcome with the crystallisation conditions demonstrated that the solvent adopts a relatively nonspecific role in determining which polymorph is obtained, and that the previously reported effect of a polymer template facilitating the formation of form IV could not be reproduced by solvent crystallisation alone. In the accompanying computational search, approximately half of the energetically feasible predicted crystal structures exhibit the C=O...H--N R2(2)(8)dimer motif that is observed in the known polymorphs, with the most stable correctly corresponding to form III. Most of the other energetically feasible structures, including the global minimum, have a C=O...H--N C(4) chain hydrogen bond motif. No such chain structures were observed in this or any other previously published work, suggesting that kinetic, rather than thermodynamic, factors determine which of the energetically feasible crystal structures are observed experimentally, with the kinetics apparently favouring nucleation of crystal structures based on the CBZ-CBZ R2(2)(8) motif., ((c) 2006 Wiley-Liss, Inc. and the American Pharmacists Association.)

The synthesis and structure of a homologous series of cationic N(2)S(2) copper(I) Schiff base complexes constructed using o-tert-butylthiobenzaldehyde and a series of terminal diamines (ethane, propane, butane) are reported. The complexes differ only in the length of the methylene chain between the imine groups. This simple modification forces the copper centre to shift geometry from a planar (1,2-diaminoethane) to a more distorted tetrahedral motif (1,4-diaminobutane). The redox potentials of the three cations were measured using cyclic voltammetry in donor (acetonitrile) and non-donor solvents (dichloromethane). The S-Cu-N angles for each complex are correlated against the respective redox potential allowing an analysis of the geometric impact on the redox potential in soft copper centres. The redox potential is observed to increase as the metal centre moves from a planar towards a tetrahedral motif. Comparing this data with the reported structures of the blue copper proteins (rusticyanin and plastocyanin) allows an assessment of the contribution of the geometry of the metal binding site to the operating potential of these proteins to be made.

A dichloromethane extract of the aerial parts of Combretum albopunctatum Suesseng afforded five phenolic compounds-three known flavonoids and two novel cyclobutane chalcone dimers. The chemical structures were determined by standard spectroscopic techniques and the structure and relative stereochemistry of one chalcone dimer, rel-(1 alpha,2 beta)-di-(2,6-dimethoxy-4-hydroxy)-benzoyl-rel-(3 alpha,4 beta)-diphenylcyclobutane, were confirmed by single crystal X-ray diffraction.

This work reports on the crystal structures of two dioxane solvates of paracetamol that are true polymorphs. The high temperature phase is an orthorhombic form, space group Pbca, Z = 8, a = 12.6078(3) A, b = 12.1129(2) A, c = 13.4138(3) A, V = 2048.52(7) A(3), (at 295 K) and the low temperature form is monoclinic, space group P21/c, Z = 4, a = 12.325(6) A, b = 11.965(4) A, c = 13.384(6) A, beta = 92.01 degrees, V = 1972.6(14)A(3) (at 123 K). The structures of these polymorphs are described as is the interrelationship between the two structures. In addition to the structural interrelationship, it is shown that the two forms undergo a reversible phase transformation. Desolvation of either form generates the stable monoclinic phase of paracetamol., (Copyright 2003 Wiley-Liss, Inc. and the American Pharmacists Association)

Two multisample laboratory powder diffractometers have been evaluated for the purpose of pattern indexing in the context of physical form screening. Both diffractometers utilise foil transmission geometry, primary monochromated radiation, and a position-sensitive detector. Data collected from six compounds (sotalol hydrochloride, hydroflumethiazide, verapamil hydrochloride, captopril, clomipramine hydrochloride, and famotidine) showed good angular resolution (FWHM as small as ca. 0.06 degrees ) and lattice parameters were easily obtained using the indexing program DICVOL-91. The extent of preferred orientation in each pattern was estimated using the DASH implementation of the March-Dollase function and is most evident with clomipramine hydrochloride and famotidine. Otherwise, the data compare favorably with reference capillary data sets. In conclusion, where there is a requirement to analyze 20-30 samples per day, with an emphasis on obtaining the high-quality data that are important in pattern recognition and imperative in indexing, the combination of foil transmission geometry, primary monochromated radiation, plus a position-sensitive detector is highly effective. The data also afford opportunities for crystal structure determination., (Copyright 2003 Wiley-Liss, Inc. and the American Pharmacists Association)

Certain protease inhibitors are effective at preventing or suppressing carcinogen-induced transformation in vitro and carcinogenesis in animal model systems. One protease inhibitor, the soybean-derived Bowman-Birk inhibitor (BBI) is particularly effective in suppressing carcinogenesis. BBI is a protein of a molecular weight of 8000 with a well-characterized ability to inhibit trypsin and chymotrypsin. BBI has been extensively studied, both as purified BBI and as an extract of soybeans enriched in BBI called BBI concentrate (BBIC). Purified BBI and BBIC have comparable suppressive effects on the carcinogenic process in a variety of in vivo and in vitro systems. BBI appears to be a universal cancer preventive agent. Purified BBI and BBIC suppress carcinogenesis as follows: in 3 different species (mice, rats, and hamsters); in several organ systems and tissue types [eg, colon, liver, lung, esophagus, cheek pouch (oral epithelium), and cells of hematopoietic origin]; and in cells of epithelial and connective tissue origin when given to animals by several different routes of administration, including the diet, leading to different types of cancer (eg, squamous cell carcinomas, adenocarcinomas, and angiosarcomas), and induced by various chemical and physical carcinogens. About half of an oral dose of BBI is taken up into the bloodstream and distributed throughout the body, with excretion via the urine. Pharmacokinetic studies of BBI have been performed in animals with radioactively labeled BBI, whereas antibodies that react with reduced BBI are being used in pharmacokinetic studies in humans. The calculated serum half-life is 10 h in both rats and hamsters. BBIC achieved Investigational New Drug status from the FDA in April 1992 (IND no. 34671; sponsor, Ann R Kennedy), and studies to evaluate BBIC as an anticarcinogenic agent in human populations began. Both BBI and BBIC prevent and suppress malignant transformation in vitro and carcinogenesis in vivo without toxicity.

Soybean Bowman-Birk protease inhibitor (BBI) is an inhibitor of serine proteases with two functional inhibitory domains of different specificities: one is specific for chymotrypsin-like proteases, the other for trypsin-like proteases. Chymase and tryptase are serine proteases which are stored in mast cell granules and released upon degranulation. This work investigated the inhibition of human chymase and tryptase by BBI. Active-site titration of human skin chymase by BBI demonstrated that BBI was a highly effective inhibitor of human chymase. Virtually stoichiometric inhibition of chymase by BBI was observed at 10 nM chymase. Kinetic studies of the inhibition reaction yielded an association rate constant of 4.0 x 10(5) M(-1) s(-1) and a dissociation rate constant of 1.7 x 10(-5) s(-1). From these two constants we estimate a K(i) of 50 pM. Chymase/BBI complexes did not dissociate in SDS-PAGE analyses under nonreducing conditions, consistent with the formation of a very tight complex with little tendency to dissociate. In contrast to chymase, human tryptase was not inhibited by BBI. These studies demonstrate that BBI is a good inhibitor of human chymase, exhibiting reaction properties better than physiological inhibitors described to date.

The influence of conjugate charge density and size on the targeting of cationic Bowman-Birk inhibitor (BBI) conjugates to the lungs was studied in mice. The biodistribution of BBI, either as the native protein or in the conjugated form (conjugated to a dicationic, tetracationic, or polycationic carrier), indicated that by increasing the charge density of BBI conjugates, the lung accumulation of the conjugates administered intravenously (i.v.) can be increased. The order of lung accumulation in these studies was as follows: polycationic- > tetracationic- > dicationic-conjugated BBI > BBI. The influence of conjugate size on lung accumulation was studied in three experiments. First, the biodistribution of poly(D-lysine) carriers of equal charge density but different molecular weight demonstrated that lung accumulation of polycationic carriers increases with an increase in carrier size. Second, the biodistributions of BBI, tyramine-derivatized poly(D-lysine)3 kDa, and poly(D-lysine)3 kDa conjugated to BBI indicated that an increase in conjugate size alone is not sufficient to promote the lung accumulation of cationic BBI conjugates. Finally, the biodistribution poly(D-lysine) complexed with heparin showed that targeting of a conjugate to the lungs can be abolished by neutralizing the charge on the carrier. Collectively, data in this paper demonstrate that the carrier-mediated targeting of BBI to the lungs is dependent on (a) cationization of BBI, (b) the conjugate positive charge density, and (c) the size of the cationic conjugate if the charge density is maintained. Also, the data show the size of the conjugate alone does not make a significant impact on lung accumulation.

Bowman-Birk protease inhibitor (BBI) is a potent anticarcinogen that suppresses malignant transformation at nanomolar concentrations. Small amounts of BBI in its native form can be measured by immunoassay using specific monoclonal antibodies (MAbs); however, the MAbs currently available are not capable of detecting BBI metabolites in human body fluids. To develop new reagents for the study of BBI exposure and pharmacokinetics, we produced four MAbs, designated 3B6, 3E3, 4H8 and 5G2, from hybridomas derived from a mouse immunized with reductively modified BBI. The epitopes recognized by the four MAbs were characterized using BBI in its native form or modified by different methods. MAb 3B6 reacted with native BBI. Partial reduction of BBI with 720 Gy of gamma radiation in an oxygen-free solution of 100 mM formate increased the reactivity of BBI with 3B6; however, extensive reduction of BBI with 100 mM DL-dithiothreitol (DTT) completely abolished this antigenic reactivity. In contrast, the other three MAbs reacted with BBI molecules that had been reduced either with 720 Gy of radiation in formate solution or with DTT. Alkylation of the radiochemically reduced BBI with N-ethylmaleimide further increased the reactivity of BBI with 3E3, 4H8 and 5G2, possibly by preventing the formation of new disulfide bonds within the BBI molecules. The binding of 4H8 and 5G2 to BBI antigen was inhibited by the binding of 3E3, and vice versa. Thus, the epitopes recognized by 3E3, 4H8 and 5G2 are probably located close to one another on the reduced BBI molecules. These three MAbs were able to react with BBI metabolites in urine samples collected from volunteers after oral administration of BBI. The ability of these MAbs to detect BBI metabolites indicates that BBI may be reductively modified in vivo and these MAbs may be useful reagents for monitoring the uptake of BBI into human tissues in cancer chemoprevention studies with BBI.

There is much evidence suggesting that compounds present in soybeans can prevent cancer in many different organ systems. The evidence for specific soybean-derived compounds having a suppressive effect on carcinogenesis in animal model systems is limited, however. There is evidence that the following isolated soybean derived products suppress carcinogenesis in vivo: a protease inhibitor, the Bowman-Birk inhibitor, inositol hexaphosphate (phytic acid) and the sterol beta-sitosterol. Other compounds that may be able to suppress carcinogenesis in animals are the soybean isoflavones. Soybean compounds reported to have other types of anticarcinogenic activity include soybean trypsin inhibitor, saponins and genistein. There is much evidence to suggest that diets containing large amounts of soybean products are associated with overall low cancer mortality rates, particularly for cancers of the colon, breast and prostate. It is believed that supplementation of human diets with certain soybean products shown to suppress carcinogenesis in animals could markedly reduce human cancer mortality rates.

X-irradiation and the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) act in a synergistic manner to increase the yield of transformed C3H10T1/2 cells in vitro. TPA modulated both translocation from the cytosol to the plasma membrane, and down regulation of protein kinase C (PKC) after prolonged (48 h) TPA exposure. N-tosyl-L-phenylalanine chloromethyl ketone (TPCK), antipain, and soybean-derived Bowman-Birk inhibitor, protease inhibitors that suppress transformation of C3H10T1/2 cells, had no effect on these TPA-mediated alterations of PKC activity, suggesting that protease inhibitors suppress TPA-stimulated promotion in vitro via a PKC-independent pathway. Several experiments were performed to determine whether non-toxic concentrations of the PKC inhibitors, N-p-tosyl-L-lysine chloromethyl ketone (TLCK), TPCK, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), or 1-(5-isoquinoline-sulfonyl)-2-methyl-piperazine (H-7), modulated the movement of cells from a quiescent state into the cell cycle. TPCK and the combination of H-7 and W-7 lowered DNA synthesis when cells were stimulated to divide by TPA. Because other protease inhibitors that slow transformation in vitro did not have the same suppressive effect on DNA synthesis, the inhibitory pathway that suppresses carcinogenic activity is likely to be different from the suppression of DNA synthesis.

The soybean-derived Bowman-Birk inhibitor (BBI) has been shown to inhibit carcinogenesis in both in vitro and in vivo model systems. In the present study, protease enzyme activity in selected tissues of male strain A mice was measured by hydrolysis of the synthetic substrate Boc-Val-Pro-Arg-MCA (t-butoxycarbornylvalylprolylarginine 7-amido-4-methylcoumarin). When added to homogenates of lung, liver and kidney in vitro, purified BBI inhibited hydrolytic activity at concentrations ranging from 10-100 microM. In vivo, hydrolytic activity was found to be significantly and in a dose-dependent manner, decreased in the lung as early as 2 h after i.p. injection of purified BBI. Less inhibition was found in the liver and kidney after in vivo administration of purified BBI. A crude preparation of BBI, given at 100 mg/kg, had no influence on the overall disposition of radiolabeled benzo[alpha]pyrene in mice although it decreased the hepatic activities of cytochrome P-450, 7-ethoxycoumarin-O-deethylase and ethoxy resorufin-O-deethylase. It is concluded that the chemopreventive effects of BBI on mouse lung tumor development are most likely mediated through its protease-inhibitory properties in the target organ rather than by a non-specific effect on metabolism and disposition of carcinogens.

Mutation frequencies in mouse cells and Chinese hamster cells were measured following single or split doses of UV light or X-rays. Split doses separated by a few to over 24 h induced no more ouabain- or 6-thioguanine-resistant mutants than did comparable single doses. These data lend no support to the possible existence of an inducible error-prone repair system in rodent cells.

Prenatal diagnosis of recessive dystrophic epidermolysis bullosa was successfully achieved at 19 weeks' gestation by indirect immunofluorescence examination of a fetal skin biopsy sample using the monoclonal antibody LH 7:2. The abortus displayed marked blistering and the diagnosis was confirmed by transmission electron microscopy (TEM). In 3 further pregnancies at risk for lethal junctional epidermolysis bullosa the diagnosis was excluded using the polyclonal antibody AA3. In all these studies the results were available within 4 h of receiving the samples. These new techniques offer a quick and simple alternative to TEM for midtrimester prenatal diagnosis of 2 severe recessive forms of epidermolysis bullosa.

In this report, we demonstrate that treatment of proliferating irradiated and nonirradiated C3H 10T1/2 cells with the protease inhibitor antipain is associated with a reduction in c-myc expression. Under conditions in which antipain treatment results in reduced c-myc transcripts, there is no effect on total RNA synthesis, growth rate, or saturation density. Antipain may be a useful inhibitor in which to further study the role of c-myc in cellular physiology.