The Application of the Biotin/Avidin System to the von Willebrand Factor Antigen Immunoassay

A vWf: Ag ELISA which uses biotinylated anti-vWf: Ag IgG and an avidin/biotinylated peroxidase (ABP) complex detection system has been developed. The sensitivity of the ELISA for vWf: Ag was 4 × 10-5 U/ml which is approximately 10-fold lower than previously reported vWf: Ag ELISA’s. The avidin used for the preparation of the ABP complex was glutaraldehyde-treated. This treatment increased the reactivity 2-3-fold as compared to ABP complex prepared using untreated avidin. The reactivity of two commercial detection reagents was also tested.

The effect of the reduction of the total assay time to 3.5 h is also described. In this form the detection limit for vWf: Ag was 2 × 10-4 U/ml, the intra-assay precision at vWf: Ag concentrations of 0.01 and 0.0025 U/ml was 3.8% and 4.9% respectively and ELISA results for normal individuals still correlated well with those obtained using electro-immunodiffusion (r = 0.93).

Human papilloma virions in the laboratory

Carcinogenic human papillomaviruses (HPV) can cause cervical, vaginal, vulvar, penile, anal, and oropharyngeal cancers. Non-carcinogenic HPVs can cause anogenital warts and recurrent respiratory papillomatosis. Currently, few research laboratories propagate, isolate or generate papilloma virions. However, there have been questions about potential exposure and risk in this setting. In this brief note, we discuss the use of wild type and laboratory-generated virions in research laboratories, potential routes of laboratory exposure, and considerations for HPV vaccination of laboratory personnel.

Human papillomavirus vaccine coverage in the United States, National Health and Nutrition Examination Survey, 2007-2008

OBJECTIVES

This study aims to estimate human papillomavirus (HPV) vaccine coverage by demographic and sexual behavior characteristics 1-2 years after vaccine licensure in a nationally representative sample of females aged 9-59 years in the United States.

METHODS

In 2007-2008, a total of 2775 females aged 9-59 years responded to questions on HPV vaccine receipt in the National Health and Nutrition Examination Survey (NHANES). Demographic and sexual characteristics were evaluated for select age categories in bivariate analyses after adjusting for survey design.

RESULTS

Overall, 15.2% of females aged 11-26 years reported HPV vaccine initiation; vaccine initiation varied significantly by age. We found no significant difference in vaccine initiation by race or poverty level in either 11-18 or 19-26-year olds. Significantly more 19-26-year olds with private insurance initiated vaccine (16.3%) than those with public insurance (4.0%) (p = 0.04). Among females aged 14-18 years, vaccine initiation was higher in those who ever had sex (28.6%) compared to those who had never had sex (17.8%) (p = 0.05).

CONCLUSIONS

These results describe HPV vaccine initiation shortly after vaccine licensure. Vaccine initiation was highest in females aged 14-18 years. Efforts should be made to increase HPV vaccine coverage for the recommended age groups.

Exposure to the anti-TNF-alpha drug thalidomide induces apoptotic cell death in human T leukemic cells

TNF-alpha is a pro-inflammatory cytokine that plays a key role in disorders due to HIV-1 infection and replication such as Kaposi sarcoma, wasting, aphthous ulcerations and progression to AIDS. The controversial drug thalidomide is anti-inflammatory, anti-angiogenic and a selective inhibitor of TNF-alpha that is being studied as a treatment for HIV-1-related disorders, immune disorders and cancer. The cellular and molecular mechanism of thalidomide is unclear despite renewed clinical interest in the drug. Previous data from this laboratory indicate that thalidomide decreases cell growth and cell-cell interactions of human T leukemic cells. The specific aim of the present study is to determine whether thalidomide administration induces cell death via apoptosis. Low dose thalidomide treatment of human T leukemic cells exhibited rapid increases in caspase-3 activity, annexin V-FITC binding and DNA disintegration that is characteristic of apoptosis. These data indicate that low doses of thalidomide signal human T leukemic cells to die by apoptosis, which is a possible method of altering inflammatory cells and inflammatory activities.

Down-regulation of cell adhesion molecules LFA-1 and ICAM-1 after in vitro treatment with the anti-TNF-alpha agent thalidomide

The tumor necrosis factor-alpha (TNF-alpha) inhibitor thalidomide is known to be a potent modulator of host immunity, a potential treatment for autoimmune disorders such as rheumatoid arthritis (RA) and a treatment for complications of HIV-1 infection. RA is an autoimmune disease of the joints that has been associated with hyperactivity of lymphocytes and other leukocytes, over-expression of pro-inflammatory cytokines (TNF-alpha and IL-1) and chronic debilitating inflammation. Thalidomide may play a role in RA treatment by altering leukocyte function through down-modulation of cell adhesion molecules necessary for leukocyte migration to inflammatory sites. The present study investigates down-regulation of cell adhesion molecules (ICAM-1 and LFA-1) and decreases in cell-cell contacts between human T leukemic (CEM) cells and human umbilical vein endothelial cells (HUVEC) after thalidomide exposure. CEM cells were cultured in RPMI 1640 medium with 0, 10 or 50 microg/ml thalidomide, stained with fluorescent monoclonal antibodies specific to ICAM-1 and LFA-1 and expression was measured with flow cytometry. For cell-cell adhesion measurements, monolayers of HUVEC cultured in Kaign's F-12 medium were incubated with thalidomide treated CEM cells stained with calcein AM. Specific cell adhesion between the two cell types was visualized with fluorescence microscopy. Thalidomide treatment significantly reduced cell adhesion molecule expression in a dose-dependent fashion and inhibited HUVEC/CEM cell adhesion. These data support the hypothesis that thalidomide has modulatory actions on leukocyte functions through expression of cell adhesion molecules.

Ethical challenges in everyday practice for healthcare lawyers

A lawyer representing healthcare clients confronts numerous ethical issues in day-to-day practice. The authors, practicing healthcare attorneys, first give a quick overview of the history of today's rules of legal ethics, and then turn to hypothetical (but realistic) scenarios to examine counsel's duties under various circumstances. The Article concludes with an examination of the overriding duties of confidentiality and privilege, which guide the analysis of ethical concerns in all areas.

Central and peripheral neurochemical alterations and immune effects of prenatal ethanol exposure in rats

In contrast to the well known effects of prenatal ethanol exposure on the central nervous system, data about its peripheral effects are scarce. Here, Sprague Dawley rats were fed a liquid diet (gestational days 0-20) containing 36% ethanol-derived calories (EDCs, group H) or were pair-fed with 18% EDCs (group L) or 0% EDCs (group C). On postnatal day 20, one male and one female from each of 10 litters per group were killed. Norepinephrine (NE) was analyzed in the frontal cortex, spleen and thymus, and dopamine, 5-hydroxytryptamine (serotonin, 5-HT) and their metabolites 3,4-dihydroxyphenylacetic acid, homevanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were analyzed in the striatum by high-performance liquid chromatography with electrochemical detection. Lymphocyte subpopulations in the spleen and thymus were also assessed in half of these litters. Significant decreases in splenic NE concentration were seen in both sexes of group H (males 27%, females 28%). Decreases in striatal 5-HT and 5-HIAA of group H subjects appeared to be sex specific (only females were significantly affected: 23% decrease in 5-HT, 37% decrease in 5-HIAA). Pronounced, dose-dependent reductions in T cell percentages were observed in both the thymus and spleen. Splenic CD8+ and CD4+ cell percentages were positively correlated with the splenic NE concentrations. It is concluded that the decreases seen in splenic T cell percentages subsequent to prenatal ethanol exposure may be caused, at least partially, by impaired noradrenergic control of this organ.

The effect of dideoxycytidine on lymphocyte subpopulations in nonhuman primates

In the present study, 2',3'-dideoxycytidine (ddC), which has antiretroviral activity, was given chronically to uninfected nonhuman primates to determine whether it produces adverse immunological or hematological effects. Nine healthy adult male rhesus monkeys were divided into three groups and given the following doses of ddC in a gelatin vehicle: group A, 0.06, 6.0, 3.0, and 1.5 mg/kg; group B, 0.6 mg/kg; group C, 0 mg/kg. Blood samples were collected for hematologic analysis and flow cytometric analyses of lymphocyte subpopulations. Chronic ddC exposure did not cause significant changes in the number of red blood cells, monocytes, or reticulocytes. The number of white blood cells and neutrophils increased and these changes were observed only in group A animals at the 1.5 mg/kg dose. The most significant alterations observed were decreases in the number of T helper cells (CD4) and B cells (CD20). CD4+ and CD20+ lymphocytes exhibited dose-related shifts that were reversible over time and after drug withdrawal. The results indicate that ddC has few hematologic effects but it does have profound but transient effects on the number of cells in lymphocyte subpopulations in normal primates.

Antigen-specific human antibodies from mice comprising four distinct genetic modifications

Human sequence monoclonal antibodies, which in theory combine high specificity with low immunogenicity, represent a class of potential therapeutic agents. But nearly 20 years after Köhler and Milstein first developed methods for obtaining mouse antibodies, no comparable technology exists for reliably obtaining high-affinity human antibodies directed against selected targets. Thus, rodent antibodies, and in vitro modified derivatives of rodent antibodies, are still being used and tested in the clinic. The rodent system has certain clear advantages; mice are easy to immunize, are not tolerant to most human antigens, and their B cells form stable hybridoma cell lines. To exploit these advantages, we have developed transgenic mice that express human IgM, IgG and Ig kappa in the absence of mouse IgM or Ig kappa. We report here that these mice contain human sequence transgenes that undergo V(D)J joining, heavy-chain class switching, and somatic mutation to generate a repertoire of human sequence immunoglobulins. They are also homozygous for targeted mutations that disrupt V(D)J rearrangement at the endogenous heavy- and kappa light-chain loci. We have immunized the mice with human proteins and isolated hybridomas secreting human IgG kappa antigen-specific antibodies.

Human immunoglobulin transgenes undergo rearrangement, somatic mutation and class switching in mice that lack endogenous IgM

We have generated transgenic mice that contain human-sequence Ig miniloci and, because they are also homozygous for a targeted disruption of their endogenous heavy chain genes, must rely on the transgene sequences for B cell receptor expression. Although the human transgenes contain only a fraction of the intact human heavy chain locus, these defined sequences are able to at least partially restore the humoral immune system in the mouse. B cells expressing human heavy chains develop in the bone marrow, populate peripheral lymphoid tissue and respond specifically to antigen. Furthermore, the heavy chain transgenes contain both human mu and gamma 1 coding exons as well as the respective mu and gamma 1 switch regions. The sequences included within the transgene are sufficient to direct class switch recombination. Transgene sequences are also sufficient to direct somatic mutation of the class-switched heavy chain genes. These observations define the upper limit of the cis-acting sequences necessary to direct heavy chain class switching and somatic mutation.

Establishing a histologic basis for false-negative mammograms

In order to explore the histology of false-negative mammograms, 264 consecutive patients with breast cancer were retrospectively reviewed until 100 patients with palpable cancers were identified. These patients were imaged by a dedicated mammographer within 6 months prior to biopsy. Nine of the 100 patients had "negative" readings originally, with 6 of the 9 still regarded as negative when re-examined after full knowledge of the tumor location. Histologic review of these six tumors showed a diffusely infiltrative pattern in five patients (three with invasive lobular carcinomas and two with multifocal, invasive ductal carcinomas). Although background breast density always serves in a critical relationship with tumor density on film, only one of these six patients showed a severe degree of mammographic breast density. Diffuse histology should be recognized as a principal cause of false-negative mammograms. Since mammography is based solely on anatomic contrasts, diffuse histology could easily prevent the perfection of this modality, calling attention to the need for improved adjunct imaging techniques.

Human immunoglobulin heavy-chain minilocus recombination in transgenic mice: gene-segment use in mu and gamma transcripts

We (N.L. and L.D.T.) have introduced a human heavy-chain minilocus into mice transgenically. Constructs contain 2 heavy-chain variable (VH; psi VH3-105 and VH5-251), 10 diversity (D), 6 heavy-chain joining (JH), and either constant (C)mu or C mu and C gamma gene segments. Several founder lines were established and studied before immunization. Seventy heavy-chain transcripts were cloned and sequenced from murine splenic B lymphocytes, and gene-segment use was assessed before and after class-switching. In general, the repertoire was "fetal" in appearance with little evidence of somatic mutation in any gene segment. The two VH gene segments were found rearranged to mu- and gamma-chain C segments, with a preference of VH5-251. We observed a preponderance of the most-J-proximal D gene (DHQ52) segments among the mu transcripts (44%). The JH gene-segment use mimics most patterns seen in human antibodies. Diversification in CDR3 was extensive and included clear examples of D inversions and D-D fusions. These data suggest that a human immunoglobulin minilocus can undergo recombinatorial processes in a manner analogous to that seen in the human fetal/preimmune repertoire. This model, in addition to providing a potential source of human monoclonal antibodies, is ideal for the study of further questions concerning immunoglobulin gene-segment recombination.

Recent developments in coal mining technology and their impact on miners' health

Advances in technology have significantly reduced the long-term health risks associated with underground coal mining. While the potential risks include exposure to hazardous substances and noise, the reduction of respirable dust in the workplace has been emphasized here because of the greater probability of exposure and the well-documented consequences. Since enactment of the Mine Health and Safety Act of 1969, great strides have been made in reducing worker exposure to respirable dust. As production rates continue to increase, particularly in longwall sections, continued advances in dust control technology will be required. These advances will be needed to meet existing, and perhaps even more stringent future, exposure limits. Mechanization has resulted in a significant reduction in exposure to hazards while increasing productivity. Use of remotely controlled equipment is also increasing rapidly, and efforts are underway to develop completely automated mining systems. These automated systems may further reduce the risk of health impairment due to the underground working environment.

A transgenic mouse that expresses a diversity of human sequence heavy and light chain immunoglobulins

We have generated transgenic mice that express a diverse repertoire of human sequence immunoglobulins. The expression of this repertoire is directed by light and heavy chain minilocus transgenes comprised of human protein coding sequences in an unrearranged, germ-line configuration. In this paper we describe the construction of these miniloci and the composition of the CDR3 repertoire generated by the transgenic mice. The largest transgene discussed is a heavy chain minilocus that includes human mu and gamma 1 coding sequences together with their respective switch regions. It consists of a single 61 kb DNA fragment propagated in a bacterial plasmid vector. Both human heavy chain classes are expressed in animals that carry the transgene. In light chain transgenic animals the unrearranged minilocus sequences recombine to form VJ joints that use all five human J kappa segments, resulting in a diversity of human-like CDR3 regions. Similarly, in heavy chain transgenics the inserted sequences undergo VDJ joining complete with N region addition to generate a human-like VH CDR3 repertoire. All six human JH segments and at least eight of the ten transgene encoded human D segments are expressed. The transgenic animals described in this paper represent a potential source of human sequence antibodies for in vivo therapeutic applications.

Therapy-related myelodysplastic syndrome in children with medulloblastoma following MOPP chemotherapy

Between 1978 and 1988, 20 children with medulloblastoma (MB) of the brain were treated postoperatively with MOPP (nitrogen mustard, vincristine, prednisone, and procarbazine). All but one received post-operative radiation prior to MOPP. Eight of 20 patients remained in continuous complete remission from MB, two of whom eventually developed myelodysplastic syndrome (MDS). Following resection of MB at age 12 months, one patient was treated with 24 courses of MOPP over 2 years without radiation therapy. She developed pancytopenia, and MDS was diagnosed 19 months after the completion of MOPP. Analysis of unstimulated bone marrow (BM) chromosomes showed structural abnormalities involving chromosomes 7, 10, 17, and 21. Eight months later, MDS evolved into acute myeloid leukemia. The second patient was diagnosed with MB at age 7 years and received postoperative craniospinal radiation followed by 12 courses of MOPP over one year. Five months after completion of MOPP, she developed MDS with monosomy 7 on chromosome analysis of bone marrow cells. Therapy-related MDS may be a complication of MOPP chemotherapy for MB in young children.

Ageing compromises gastrointestinal mucosal immune response in the rhesus monkey

Most research on the effects of ageing on gut mucosal immunity has been performed using rodents. However, there are inherent difficulties in the extrapolation of rodent data to humans. This study was initiated to define age-related changes in the gastrointestinal (GI) mucosal immune response in non-human primates. Antibody responses were measured in young and old rhesus monkeys (Macaca mulatta) immunized intraduodenally with cholera toxin (Ctx)/cholera toxoid (Ctd). Antigen-specific immunoglobulin A (IgA) antibody levels were markedly lower while anti-Ctx IgG and IgM titres were higher in the intestinal lavage samples of old as compared to young animals. Total IgA concentrations in gut lavage were independent of age or immune status. Measurable titres of anti-Ctx IgA in the saliva of both age groups support the common mucosal immune hypothesis. Flow cytometric analysis was used to identify age-related shifts in the expression of cell surface antigens on peripheral blood lymphocytes. The relative number of both IgA+ and Ctx+ cells was dramatically reduced in the blood of old monkeys. Collectively, these data suggest that the GI mucosal immune response to Ctx is compromised in old rhesus macaques. The deficit in immune responsiveness, namely reduced anti-Ctx IgA antibody secretion into the intestinal lumen, may be a consequence of alterations in the process of maturation and homing of specific antibody-secreting B lymphocytes.

Cytogenetic features of childhood acute lymphoblastic leukemia. A concordance study and a Pediatric Oncology Group study

Cytogenetic analysis yields important objective information that has been shown to correlate with both patient response to therapeutic intervention and patient survival. Bone marrow samples are submitted to a common reference laboratory for cytogenetic analysis from children with newly diagnosed acute lymphoblastic leukemia (ALL) registered on frontline Pediatric Oncology Group (POG) therapeutic studies (classification 8600 series). A portion of the sample from the Texas Children's Hospital (Houston, TX) a POG affiliate, was also submitted to a local cytogenetics laboratory for analysis. This study retrospectively compares karyotypic data and methods from the Laboratory of Medical Genetics, University of Alabama at Birmingham (reference laboratory) with those of the Kleberg Cytogenetics Laboratory at the Baylor College of Medicine (local laboratory) over a 35-month period to evaluate the effect of differences in specimen procurement, handling, and laboratory methodology on yield of cytogenetic information. Each laboratory was able to identify clonal abnormalities in 72% of cases examined during the last year of the study. When these data were combined, the overall detection rate of clonal abnormalities was 87.5%. Utilizing the same bone marrow aspirate from 73 children, this study demonstrates that cytogenetic methodology significantly affects the yield of identifiable clonal abnormalities, while variables such as overnight shipping have no discernable effect. This study also supports the contention that central laboratory testing effectively yields information critical to ongoing large-scale research endeavors.

9p monosomy in a patient with Gilles de la Tourette's syndrome

Gilles de la Tourette's syndrome (GTS) is a genetic disorder characterized by multiple motor and vocal tics, obsessive-compulsive disorder, and attention-deficit disorder. Family studies support the presence of an autosomal dominant gene; however, to date, an assignment for the GTS locus has not been made. We present the case of a boy with GTS and a deletion of the terminal portion of the short arm of chromosome 9, del(9)(qter----p2304:).

Construction of tracer plasmids for Bacillus sphaericus 1593 utilizing the xylE gene from Pseudomonas putida

Genetically engineered microorganisms (GEMS) released into the environment must be traceable in order to accurately assess their impact on the area of release. Tracer genes other than those that introduce antibiotic resistance are preferred for use in identifying genetically engineered strains. In this study, we describe the construction of a series of tracer plasmids for use in Bacillus sphaericus using the xylE gene from the Pseudomonas putida TOL plasmid. This gene codes for the enzyme catechol 2,3-dioxygenase which converts the colorless substance catechol to 2-hydroxymuconic semialdehyde, a yellow product which is easily detected. Colonies of cells which express the xylE gene turn yellow shortly after being exposed with a solution of catechol.

Cytogenetic abnormalities common to adenocarcinoma metastatic to the pleura

Recently, i(8q) was suggested to be a nonrandom chromosomal abnormality characteristic of adenocarcinoma of the lung. To further investigate this observation, a chromosomal analysis of five cases of pleural effusions representing metastatic adenocarcinoma from different primary sites (two lung, two breast, and one stomach) was undertaken. The i(8q) occurred in three of the tumors, one from each of the three different primary sites. In addition, abnormalities of the short arm of chromosome 3 and extra copies of chromosome 7, both of which have been associated with adenocarcinoma of the lung, were simultaneously present in the same three tumors. Our findings demonstrate that i(8q) is not specific for adenocarcinoma of the lung and that it may have a role in the pathogenesis of adenocarcinomas from multiple organs. The simultaneous presence of i(8q), abnormalities of 3p, and extra copies of chromosome 7 may indicate a relationship among these abnormalities in multistep carcinogenesis or the development of metastatic potential.

Modification of the drop dialysis technique for use with larger volume samples

Desalting of nucleic acids by the drop dialysis method is limited by the fact that only small volume samples can be used due to the lack of sample containment on the membrane filters. A specially modified Styrafoam cup can be used as a membrane filter holder which serves to contain the sample, thus permitting dialysis of larger sample volumes.

Distribution of fast myosin heavy chain isoforms in thick filaments of developing chicken pectoral muscle

Colloidal gold-conjugated monoclonal antibodies were prepared to stage-specific fast myosin heavy chain (MHC) isoforms of developing chicken pectoralis major (PM). Native thick filaments from different stages of development were reacted with these antibodies and examined in the electron microscope to determine their myosin isoform composition. Filaments prepared from 12-d embryo, 10-d chick, and 1-yr chicken muscle specifically reacted with the embryonic (EB165), neonatal (2E9), and adult (AB8) antimyosin gold-conjugated monoclonal antibodies, respectively. The myosin isoform composition was more complex in thick filaments from stages of pectoral muscle where more than one isoform was simultaneously expressed. In 19-d embryo muscle where both embryonic and neonatal isoforms were present, three classes of filaments were found. One class of filaments reacted only with the embryonic antibody, a second class reacted only with the neonatal-specific antibody, and a third class of filaments were decorated by both antibodies. Similar results were obtained with filaments prepared from 44-d chicken PM where the neonatal and adult fast MHCs were expressed. These observations demonstrate that two myosin isoforms can exist in an individual thick filament in vivo. Immunoelectron microscopy was also used to determine the specific distribution of different fast MHC isoforms within individual filaments from different stages of development. The anti-embryonic and anti-adult antibodies uniformly decorated both homogeneous and heterogeneous thick filaments. The neonatal specific antibody uniformly decorated homogeneous filaments; however, it preferentially decorated the center of heterogeneous filaments. These observations suggest that neonatal MHC may play a specific role in fibrillogenesis.

The application of the biotin/avidin system to the von Willebrand factor antigen immunoassay

A vWf: Ag ELISA which uses biotinylated anti-vWf: Ag IgG and an avidin/biotinylated peroxidase (ABP) complex detection system has been developed. The sensitivity of the ELISA for vWf: Ag was 4 X 10(-5) U/ml which is approximately 10-fold lower than previously reported vWf: Ag ELISA's. The avidin used for the preparation of the ABP complex was glutaraldehyde-treated. This treatment increased the reactivity 2-3-fold as compared to ABP complex prepared using untreated avidin. The reactivity of two commercial detection reagents was also tested. The effect of the reduction of the total assay time to 3.5 h is also described. In this form the detection limit for vWf: Ag was 2 X 10(-4) U/ml, the intra-assay precision at vWf: Ag concentrations of 0.01 and 0.0025 U/ml was 3.8% and 4.9% respectively and ELISA results for normal individuals still correlated well with those obtained using electro-immunodiffusion (r = 0.93).

An inhibitor to factor VIII:C in a patient with possible combined haemophilia A and von Willebrand's disease

A factor VIII inhibitor has been found in a patient with an unusual combination of factor VIII-related properties. The inhibitor is directed specifically against the clotting activity (VIII:C) of the factor VIII complex. It behaves in a similar fashion to high responding inhibitors of factor VIII seen in haemophilia A patients and it was characterised as an immunoglobulin of the IgG class. Laboratory results from the patient and his family show considerable variation of factor VIII-related properties between various individuals. Overall, the data suggests the co-existence of haemophilia A and von Willebrand's disease in the family and the presence of both diseases in the patient.

An Inhibitor to Factor VIII: C in a Patient with Possible Combined Haemophilia A and von Willebrand’s Disease

A factor VIII inhibitor has been found in a patient with an unusual combination of factor VIII-related properties. The inhibitor is directed specifically against the clotting activity (VIII :C) of the factor VIII complex. It behaves in a similar fashion to high responding inhibitors of factor VIII seen in haemophilia A patients and it was characterised as an immunoglobulin of the IgG class. Laboratory results from the patient and his family show considerable variation of factor VUI-related properties between various individuals. Overall, the data suggests the co-existence of haemophilia A and von Willebrand’s disease in the family and the presence of both diseases in the patient.

The enzymic derivation of citrulline residues from arginine residues in situ during the biosynthesis of hair proteins that are cross-linked by isopeptide bonds

An enzymic activity present in hair follicles is described that can convert arginine residues to citrulline residues in proteins in situ. The Ca2+ dependent enzyme activity has been detected in hair follicle extracts but not in similar extracts of serum, liver or brain. The enzyme appears to act on proteins other than hair proteins and the citrulline produced can be quantitated in acid hydrolysates by a colorimetric procedure. The formation of citrulline has been confirmed by amino acid analysis and does not appear to be related to the formation of isopeptide linkages which is catalysed by the transamidase present in hair follicles.