Protein phosphorylation and growth control

Many growth factor receptors and retroviral transforming proteins share the property of phosphorylating proteins on tyrosine. Several substrates for both types of protein-tyrosine kinase have been identified. Treatment of quiescent cells with growth factors such as EGF and PDGF, whose receptors have ligand-stimulated protein-tyrosine kinase activities, induces tyrosine phosphorylation of three proteins, p45, p42 and p41. Two phosphorylated forms of p42 are found, the more basic of which is present in some but not all cells transformed by viral protein-tyrosine kinases. p42 is rapidly (as early as 1 min) but transiently (decreased to baseline by 2h) phosphorylated following PGDF or EGF treatment of quiescent fibroblasts. At saturating levels of mitogen the stoichiometry of p42 phosphorylation is greater than 50%. p42 is a highly conserved, rare (0.002% of total cell protein), soluble cytoplasmic protein. IGF I and insulin, whose receptors also have ligand-stimulated protein-tyrosine kinase activity, induce p42 phosphorylation in appropriate cells. In the case of insulin this effect has been observed in cells with large numbers of insulin receptors. p42 is also phosphorylated in response to mitogens whose receptors lack protein-tyrosine kinase activity, for example 12-O-tetradecanoylphorbol-13-acetate (TPA) and thrombin. For TPA there is evidence that this is an indirect effect due to the activation of a protein-serine/threonine kinase. On the basis of the highly conserved nature of this response and its generality, it seems likely that tyrosine phosphorylation of p42 is important for at least early responses to mitogens.

CD5+ B cells are preferentially expanded in rabbit appendix: the role of CD5 in B cell development and selection

Although only a small proportion of mouse and human B cells are CD5(+), most adult rabbit B cells express CD5. However, CD5 was not detectable on the majority of B cells in neonatal appendix 1 and 3days after birth. Cell trafficking studies demonstrated that CD5(+) and CD5(-) CD62L(+) B cells from bone marrow migrated into appendix. There, CD5(+) B cells were preferentially expanded and predominated by approximately 2weeks of age. In mutant ali/ali rabbits, VHa2(+) B cells develop through gene conversion-like alteration of rearranged VH genes upstream of deleted VH1a2. Correlated appearance of individual CD5(+) germinal centers and VHa2(+) B-cells in mutant appendix suggests that CD5 binding positively selects cells with a2(+) framework regions that bind CD5. Following negative and positive selection, cells with diversified rearranged heavy- and light-chain sequences exit appendix, migrate to peripheral tissues and constitute the preimmune repertoire of CD5(+) B cells that encounter foreign antigens.

Rabbit immune repertoires as sources for therapeutic monoclonal antibodies: the impact of kappa allotype-correlated variation in cysteine content on antibody libraries selected by phage display

The rabbit immune repertoire has long been a rich source of diagnostic polyclonal antibodies. Now it also holds great promise as a source of therapeutic monoclonal antibodies. On the basis of phage display technology, we recently reported the first humanization of a rabbit monoclonal antibody. The allotypic diversity of rabbit immunoglobulins prompted us to compare different rabbit immune repertoires for the generation and humanization of monoclonal antibodies that bind with strong affinity to antigens involved in tumor angiogenesis. In particular, we evaluated the diversity of unselected and selected chimeric rabbit/human Fab libraries that were derived from different kappa light chain allotypes. Most rabbit light chains have an extra disulfide bridge that links the variable and constant domains in addition to the two intrachain disulfide bridges shared with mouse and human kappa light chains. Here we evaluate the impact of this increased disulfide bridge complexity on the generation and selection of chimeric rabbit/human Fab libraries. We demonstrate that rabbits with mutant bas and wild-type parental b9 allotypes are excellent sources for therapeutic monoclonal antibodies. Featured among the selected clones with b9 allotype is a rabbit/human Fab that binds with a dissociation constant of 1nM to both human and mouse Tie-2, which will facilitate its evaluation in mouse models of human cancer. Examination of 228 new rabbit antibody sequences allowed for a comprehensive comparison of the LCDR3 and HCDR3 length diversity in rabbits. This study revealed that rabbits exhibit an HCDR3 length distribution more closely related to human antibodies than mouse antibodies.

Trends in pathology graduate medical education

Comprehensive data show trends in graduate medical education in pathology with regard to the numbers of accredited programs, persons certified from those programs, and demographics of the population of first year-trainees in pathology. Experience with US seniors and foreign-trained physicians in the PGY match process for pathology from 1991 through 2000 is presented, along with data on the types of medical schools generating pathology trainees for the PGY-1 year and the top medical schools of origin of US medical graduates who completed the program and became certified in pathology between 1995 and 1999. The impact of reimbursement of the credentialing year is also addressed through data collected from the PRODS Survey 2000, and those results are reviewed. Finally, turnover rates among pathology program directors of combined AP/CP programs and subspecialty programs since 1994 are presented. An analysis of these trends is provided, along with suggestions to improve both the perception of careers in pathology and the actual choice of a career in pathology.

Association of reactive nitrogen species metabolites, myeloperoxidase, and airway inflammation in lung transplants

BACKGROUND

We have previously reported that patients who had single or double lung transplants had higher concentrations than controls of nitrite and nitrate, which are metabolites of reactive nitrogen species (RNS), in bronchoalveolar lavage fluid (BALF) and serum.

METHODS

This study investigates implications of RNS metabolites as markers of airway inflammation in a distinct group of lung transplant patients (n = 40). All patients underwent spirometry, routine surveillance transbronchial lung biopsies, and bronchoalveolar lavage as required by clinical protocol. Four normal controls also had bronchoscopy for measurement of BALF nitrite (NO2-) and nitrate (NO3-). BALF NO2- and NO3-, myeloperoxidase (MPO), protein, and urea were assayed. Total nitrite (NO2- plus enzymatically reduced NO3-) and urea were measured in serum.

RESULTS

BALF RNS metabolites were mainly NO3-. Forced expiratory volume in 1 s (FEV1) obtained near bronchoscopy was compared with best postoperative FEV1. Total nitrite in transplant patients' BALF and serum were 3.8 +/- 0.2 and 49 +/- 5 microM, respectively. Total nitrite in controls' BALF and serum were 2.2 +/- 0.7 and 19 +/- 2 microM, respectively (P < 0.05 compared with transplant values). Serum total nitrite correlated (Pearson product moment) with percentage of neutrophils in BALF (R = 0.650, P < 0.0001), MPO (R = 0.431, P = 0.0055), change in FEV1 from baseline (deltaFEV1) (R = -0348, P = 0.0298), and days after transplantation (R = 0.345, P = 0.0294). None of the associated variables, airway inflanmmation (quantified as a score, "B"), deltaFEV1, serum, or BALF total nitrite, were explained by infection. Univariate analysis of airway inflammation in patients showed that it was associated with BALF neutrophils, deltaFEV1, and serum total nitrite.

CONCLUSIONS

Serum nitrite appears to reflect the degree of airway inflammation in this lung-transplant study group.

The utility of open lung biopsy following lung transplantation

BACKGROUND

Most pulmonary complications associated with lung transplantation have non-specific clinical characteristics. Furthermore, common diagnostic modalities, including bronchoscopy with transbronchial biopsy (TBB), often do not render a definitive diagnosis. In this study, we reviewed our experience with open lung biopsy (OLB) following lung transplantation, specifically regarding its ability to safely provide clinically relevant information that affects therapeutic decisions.

METHODS

From October 1989 to March 2000, 202 patients underwent lung transplantation at our institution. We reviewed the clinical course of the 42 patients who received 48 OLBs. Of these patients, we determined the pre-operative clinical condition, preceding TBB histologic information, OLB histology, treatment changes, and procedural complications as a result of the OLB.

RESULTS

A new, clinically unsuspected diagnosis was made in 14 biopsies (29% of all OLB), and all of these resulted in therapy changes. Thirty-two biopsies (67% of all OLB) confirmed our clinical suspicions, and new therapy was initiated in 30 of these patients. Two patients (4% of all OLB) had non-diagnostic OLB. Four biopsies (8% of all OLB), including the 2 non-diagnostic OLBs, did not result in any therapy changes or initiation of new therapy. Complications occurred in 3 patients, all of whom had an air leak for >7 days.

CONCLUSION

Open lung biopsy in lung transplant patients renders a new, unsuspected diagnosis in nearly one third of patients and leads to specific, directed therapy in the vast majority of patients. Open-lung biopsy can be performed safely and should be considered when diagnosis is uncertain in clinically deteriorating patients.

Cost-based (Part A) pathology physician services. Origin, current spectrum, and future

The authors review pathology cost-based services, how they developed, their current status, and future applications in a managed care environment. Special emphasis is given to the utility of outcomes analysis for pathology cost-based services.

A review of carisoprodol deaths in Jefferson County, Alabama

BACKGROUND

Carisoprodol is a skeletal muscle relaxant with the potential for abuse. A carisoprodol overdose is rarely considered fatal. Nevertheless, we encountered carisoprodol in several cases, prompting review of our experience.

METHODS

We did a retrospective study of cases examined at the Jefferson County Coroner/Medical Examiner Office from January 1, 1986, to October 31, 1997, reviewing investigative reports and autopsy findings.

RESULTS

Carisoprodol was present in 24 cases. Seventeen decedents died of acute drug intoxication. Carisoprodol was never the sole drug detected at autopsy, nor was it ever the sole cause of death. Propoxyphene was a co-intoxicant in 8 of the 24 cases.

CONCLUSIONS

Carisoprodol causes respiratory depression. Since the mechanism of death was respiratory depression in 82% of the decedents who died of acute intoxication, we consider that carisoprodol was probably responsible, in part, for those deaths. The simultaneous use of propoxyphene and carisoprodol seems to be especially dangerous.

Further studies on anti- and proconvulsant effects of inhibitors of nitric oxide synthase in rodents

We confirmed that the effects of inhibitors of nitric oxide (NO) synthase, such as Nomega-nitro-L-arginine methyl ester and Nomega-nitro-L-arginine, differ depending on several experimental factors. Both compounds but not their less active enantiomers delayed picrotoxin-induced clonus in mice yet increased the incidence of clonus following low-dose picrotoxin. Nomega-nitro-L-arginine methyl ester significantly reduced the latencies of both myoclonus and clonus in older but not younger Sprague-Dawley rats receiving pentylenetetrazol s.c. By contrast, there was no significant change in the latencies for myoclonus and clonus in Wistar rats (older and younger). However, when pentylenetetrazol was administered i.p. rather than s.c., Nomega-nitro-L-arginine methyl ester dramatically increased latencies of convulsive indicators, including tonus, in both Sprague-Dawley and Wistar rats. Nomega-nitro-L-arginine methyl ester also delayed tonus but not myoclonus or clonus in mice, regardless of the systemic route of administration of pentylenetetrazol. Both Nomega-nitro-L-arginine methyl ester and NG-nitro-L-arginine increased the tonic CD50 of pentylenetetrazol in mice and Nomega-nitro-L-arginine methyl ester delayed 4-aminopyridine-induced tonus. However, Nomega-nitro-L-arginine methyl ester reduced the tonic CD50 of both picrotoxin and 4-aminopyridine in mice and failed to suppress tonus following maximal electroshock. Evidently, inhibitors of NO synthase are not universally effective antitonic drugs.

A 15-year review of railway-related deaths in Jefferson County, Alabama

A retrospective computer search of the records of the Jefferson County Coroner/Medical Examiner Office covering the 15-year period from 1981 to 1995 revealed 86 cases in which either a train caused death or in which a body was found dead by the tracks. The average age of the decedents was 39 years (range, 3 weeks-87 years). Men accounted for 88% of the deaths. The manners of death were as follows: three natural, 64 accident, seven suicide, six homicide, and six undetermined. Six decedents were found dead by the tracks, but death was not caused by a train. Six decedents were railroad employees who died on the job. In 47 cases, the decedents were trespassing on railroad property. Five trespassers were riding the rails, and 42 were pedestrians struck by a train. Motor vehicle collisions with trains claimed 27 lives--19 drivers and eight passengers. All together, 45% of the decedents were intoxicated. Intoxication was greatest by far in individuals witnessed to have been lying on the tracks before being hit by a train. The nature of individuals riding the rails has changed in the past few decades. Freight trains today are being used by illegal immigrants as transportation within the United States. The majority of traffic fatalities occurred because the driver intentionally tried to beat the train to the crossing. These drivers were seldom intoxicated, and only two were teenagers. Lives of such impatient drivers might be spared by the installation of a crossing guard-rail that cannot be circumvented.

Rabbit DQ52 and DH gene expression in early B-cell development

Rabbits predominantly rearrange the most 3'VH gene (VH1); thus combinatorial diversity is very limited. In man and mouse, the most 3'DH gene, DQ52, is preferentially rearranged early in B-cell development. To test whether this preference for rearranging a DH gene segment based on 3' end proximity exists in rabbit, we cloned and sequenced the rabbit DQ52 gene. The 11 base pair coding region sequence is identical to a published mouse DQ52, and 81.8% similar to the human sequence. It is localized approximately 805 bp upstream of the JH1 gene. However, the 3' recombination signal sequence has an atypical nonamer. We prepared mRNA from 15- to 28-day fetal rabbits and amplified expressed VDJ sequences of mu mRNA by RT-PCR. The PCR products with VDJ rearrangements were cloned and sequenced. As expected, 44 of 45 VDJ sequences reflected use of the 3' VH1a2 gene, but the DQ52 gene was utilized very infrequently, if at all. We found only one VDJ sequence from 28-day fetal liver B-cells with 8 bp that matched the germline DQ52 sequence. Instead of expressing DQ52, another DH gene, Df was frequently expressed. We cloned the genomic Df gene and localized it about 32 kb upstream of the JH region. Thus, in contrast to man and mouse, rabbits preferentially express a DH gene located in the middle of the DH region early in B cell ontogeny. This may correlate with more frequent initial rearrangement of VH to DH in rabbit B cells.

Characterization of a rabbit germ-line VH gene that is a candidate donor for VH gene conversion in mutant Alicia rabbits

Normal rabbits preferentially rearrange the 3'-most VH gene, VH1, to encode Igs with VHa allotypes, which constitute the majority of rabbit serum Igs. A gene conversion-like mechanism is employed to diversify the primary Ab repertoire. In mutant Alicia rabbits that derived from a rabbit with VHa2 allotype, the VH1 gene was deleted. Our previous studies showed that the first functional gene (VH4) or VH4-like genes were rearranged in 2- to 8-wk-old homozygous Alicia. The VH1a2-like sequences that were found in splenic mRNA from 6-wk and older Alicia rabbits still had some residues that were typical of VH4. The appearances of sequences resembling that of VH1a2 may have been caused by gene conversions that altered the sequences of the rearranged VH or there may have been rearrangement of upstream VH1a2-like genes later in development. To investigate this further, we constructed a cosmid library and isolated a VH1a2-like gene, VH12-1-6, with a sequence almost identical to VH1a2. This gene had a deleted base in the heptamer of its recombination signal sequence. However, even if this defect diminished or eliminated its ability to rearrange, the a2-like gene could have acted as a donor for gene-conversion-like alteration of rearranged VH genes. Sequence comparisons suggested that this gene or a gene like it could have acted as a donor for gene conversion in mutant Alicia and in normal rabbits.

Characterization of a rabbit germ-line VH gene that is a candidate donor for VH gene conversion in mutant Alicia rabbits

Normal rabbits preferentially rearrange the 3'-most VH gene, VH1, to encode Igs with VHa allotypes, which constitute the majority of rabbit serum Igs. A gene conversion-like mechanism is employed to diversify the primary Ab repertoire. In mutant Alicia rabbits that derived from a rabbit with VHa2 allotype, the VH1 gene was deleted. Our previous studies showed that the first functional gene (VH4) or VH4-like genes were rearranged in 2- to 8-wk-old homozygous Alicia. The VH1a2-like sequences that were found in splenic mRNA from 6-wk and older Alicia rabbits still had some residues that were typical of VH4. The appearances of sequences resembling that of VH1a2 may have been caused by gene conversions that altered the sequences of the rearranged VH or there may have been rearrangement of upstream VH1a2-like genes later in development. To investigate this further, we constructed a cosmid library and isolated a VH1a2-like gene, VH12-1-6, with a sequence almost identical to VH1a2. This gene had a deleted base in the heptamer of its recombination signal sequence. However, even if this defect diminished or eliminated its ability to rearrange, the a2-like gene could have acted as a donor for gene-conversion-like alteration of rearranged VH genes. Sequence comparisons suggested that this gene or a gene like it could have acted as a donor for gene conversion in mutant Alicia and in normal rabbits.

VH gene expression and regulation in the mutant Alicia rabbit. Rescue of VHa2 allotype expression

Rabbits of the Alicia strain, derived from rabbits expressing the VHa2 allotype, have a mutation in the H chain locus that has a cis effect upon the expression of VHa2 and VHa- genes. A small deletion at the most J-proximal (3') end of the VH locus leads to low expression of all the genes on the entire chromosome in heterozygous ali mutants and altered relative expression of VH genes in homozygotes. To study VH gene expression and regulation, we used the polymerase chain reaction to amplify the VH genes expressed in spleens of young and adult wild-type and mutant Alicia rabbits. The cDNA from reverse transcription of splenic mRNA was amplified and polymerase chain reaction libraries were constructed and screened with oligonucleotides from framework regions 1 and 3, as well as JH. Thirty-three VH-positive clones were sequenced and analyzed. We found that in mutant Alicia rabbits, products of the first functional VH gene (VH4a2), (or VH4a2-like genes) were expressed in 2- to 8-wk-olds. Expression of both the VHx and VHy types of VHa- genes was also elevated but the relative proportions of VHx and VHy, especially VHx, decreased whereas the relative levels of expression of VH4a2 or VH4a2-like genes increased with age. Our results suggest that the appearance of sequences resembling that of the VH1a2, which is deleted in the mutant ali rabbits, could be caused by alterations of the sequences of the rearranged VH4a2 genes by gene conversions and/or rearrangement of upstream VH1a2-like genes later in development.

VH gene expression and regulation in the mutant Alicia rabbit. Rescue of VHa2 allotype expression

Rabbits of the Alicia strain, derived from rabbits expressing the VHa2 allotype, have a mutation in the H chain locus that has a cis effect upon the expression of VHa2 and VHa- genes. A small deletion at the most J-proximal (3') end of the VH locus leads to low expression of all the genes on the entire chromosome in heterozygous ali mutants and altered relative expression of VH genes in homozygotes. To study VH gene expression and regulation, we used the polymerase chain reaction to amplify the VH genes expressed in spleens of young and adult wild-type and mutant Alicia rabbits. The cDNA from reverse transcription of splenic mRNA was amplified and polymerase chain reaction libraries were constructed and screened with oligonucleotides from framework regions 1 and 3, as well as JH. Thirty-three VH-positive clones were sequenced and analyzed. We found that in mutant Alicia rabbits, products of the first functional VH gene (VH4a2), (or VH4a2-like genes) were expressed in 2- to 8-wk-olds. Expression of both the VHx and VHy types of VHa- genes was also elevated but the relative proportions of VHx and VHy, especially VHx, decreased whereas the relative levels of expression of VH4a2 or VH4a2-like genes increased with age. Our results suggest that the appearance of sequences resembling that of the VH1a2, which is deleted in the mutant ali rabbits, could be caused by alterations of the sequences of the rearranged VH4a2 genes by gene conversions and/or rearrangement of upstream VH1a2-like genes later in development.

Bronchiolitis obliterans organizing pneumonia associated with systemic lupus erythematosus

Bronchiolitis obliterans organizing pneumonia (BOOP) is a pathologic entity characterized by the formation of plugs of fibrous tissue in bronchioles and alveolar ducts. It has been described in association with several connective tissue diseases including rheumatoid arthritis, polymyositis-dermatomyositis, and mixed connective tissue disease. Well-documented reports of BOOP in patients with systemic lupus erythematosus (SLE) are limited. We report two patients with SLE who presented with subacute respiratory illnesses due to BOOP, adding further strength to the association of this entity with SLE.

Intrapulmonary teratoma: a case report and review of the literature

Intrapulmonary teratomas are rare; only 30 cases have been reported in the world literature. These tumors are thought to originate from the third pharyngeal pouch. They occur equally in men and women and usually are diagnosed in the second to fourth decade of life. They are more often benign than malignant, although malignant lesions may have a favorable postoperative prognosis and benign lesions may exhibit high morbidity and mortality because of their size and location. These tumors present radiographically as lobulated masses that may contain calcification or peripheral collections of air. They most often occur in the upper lobes. The computed tomographic findings of intrapulmonary teratoma are less well known but have been described in two cases. An additional case is presented with a review of the literature and a tabular summary of the characteristics of this unusual entity.

Evolutionarily conserved organization and sequences of germline diversity and joining regions of the rabbit T-cell receptor beta 2 chain

We previously reported that there are three different copies of T-cell receptor beta chain constant region (C beta) genes in some rabbits, two of which are present on an approximately 16-kb and one on an approximately 6-kb Eco RI fragment. We also reported that one of the C beta genes on the approximately 16-kb fragment was chimeric, with a 5' cluster of J beta 2 segments and a 3' untranslated region of beta 1 type. Here we report the complete genomic sequences of the D beta 2 and J beta 2 segments associated with the chimeric C beta gene. The rabbit D beta 2 gene segment has very strong similarity to both its human and mouse counterparts. The sequence similarity also extends rather far from the coding region in both 5' and 3' directions. The content and organization of rabbit J beta 2 gene segments is similar to those found in both human and mouse. The rabbit J beta 2 cluster has six functional segments and one pseudogene, as well as a remnant of another pseudogene between J beta 2.2 and J beta 2.3 equivalent to the one found in man in the same location. The J beta 2.5 gene segment of rabbit has lost the splice signal and is a pseudogene unlike its counterparts in man and mouse. Overall analysis of the rabbit D beta 2-J beta 2 region reveals a closer similarity to human than mouse. However, the general organization of the gene segments in the D beta 2-J beta 2 regions of all three species is remarkably conserved over long stretches of DNA sequence.

Molecular analysis of recombination sites within the immunoglobulin heavy chain locus of the rabbit

Previously, recombinations involving genes of the rabbit immunoglobulin heavy chain locus have been documented serologically. These data indicated that the sites at which the causative recombination events occurred could have been anywhere from within the VH gene cluster up to, or 3' of, C mu. Since these sites could not be localized further by serological methods, we attempted to do this using techniques of molecular biology. DNAs from homozygous recombinant rabbits and from the appropriate non-recombinant parental haplotypes were characterized using Southern blots hybridized with a panel of probes derived from cloned regions of the rabbit immunoglobulin heavy chain gene complex. In all three recombinants, the site was downstream of the entire VH cluster and upstream of the JH cluster within an approximately 50 kilobase (kb) region containing expanses of repetitive-sequence DNA as well as DH genes. DH-specific probes further showed that in two of the recombinants, the recombination appears to have occurred within or 5' of DH1 and 5' of DH2 genes; in the third it occurred 3' of the DH2 genes but at least approximately 5 kb 5' of the JH region.

Preferrential rearrangement in normal rabbits of the 3' VHa allotype gene that is deleted in Alicia mutants; somatic hypermutation/conversion may play a major role in generating the heterogeneity of rabbit heavy chain variable region sequences

The rabbit is unique in having well-defined allotypes in the variable region of the heavy chain. Products of the VHa locus, (with alleles a1, a2, and a3), account for the majority of the serum immunoglobulins. A small percentage of the serum immunoglobulins are a-negative. In 1986, Kelus and Weiss described a mutation that depressed the expression of the Ig VH a2 genes in an a1/a2 rabbit. From this animal the Alicia rabbit strain was developed and the mutation was termed ali. We previously showed, using Southern analysis and the transverse alternating field electrophoresis technique, that the difference between the ali rabbit and normal is a relatively small deletion including some of the most 3' VH genes. The most JH proximal 3' VH1 genes in DNA from normal rabbits of a1, a2 and a3 haplotypes encode a1, a2 and a3 molecules respectively, and it has been suggested that these genes are responsible for allelic inheritance of VHa allotypes. The present study suggests that the 3' end of the VH locus probably plays a key role in regulation of VH gene expression in rabbits because VH gene(s) in this region are the target(s) of preferential VDJ rearrangements. This raises the possibility that mechanisms such as somatic gene conversion and hypermutation are at work to generate the antibody repertoire in this species. Our data support the view that the 3' VH1 gene may be the preferred target for rearrangement in normal rabbits, and for the normal chromosome in heterozygous ali animals. However, homozygous ali rabbits with a deletion that removed the a2-encoding VH1 on both chromosomes do survive, rearrange other VH genes and produce normal levels of immunoglobulins as well as a significant percentage of B cells which bear the a2 allotype. This challenges the view that one VH gene, VH1, is solely responsible for the inheritance pattern of VHa allotypes.

Altered phenotypic expression of immunoglobulin heavy-chain variable-region (VH) genes in Alicia rabbits probably reflects a small deletion in the VH genes closest to the joining region

Rabbits of the Alicia strain have a mutation (ali) that segregates with the immunoglobulin heavy-chain (lgh) locus and has a cis effect upon the expression of heavy-chain variable-region (VH) genes encoding the a2 allotype. In heterozygous a1/ali or a3/ali rabbits, serum immunoglobulins are almost entirely the products of the normal a1 or a3 allele and only traces of a2 immunoglobulin are detectable. Adult homozygous ali/ali rabbits likewise have normal immunoglobulin levels resulting from increased production of a-negative immunoglobulins and some residual ability to produce the a2 allotype. By contrast, the majority of the immunoglobulins of wild-type a2 rabbits are a2-positive and only a small percentage are a-negative. Genomic DNAs from homozygous mutant and wild-type animals were indistinguishable by Southern analyses using a variety of restriction enzyme digests and lgh probes. However, when digests with infrequently cutting enzymes were analyzed by transverse alternating-field electrophoresis, the ali DNA fragments were 10-15 kilobases smaller than the wild type. These fragments hybridized to probes both for VH and for a region of DNA a few kilobases downstream of the VH genes nearest the joining region. We suggest that this relatively small deletion affects a segment containing 3' VH genes with important regulatory functions, the loss of which leads to the ali phenotype. These results, and the fact that the 3' VH genes rearrange early in B-cell development, indicate that the 3' end of the VH locus probably plays a key role in regulation of VH gene expression.

Genetic analyses of restriction fragment length polymorphisms using high molecular weight DNA from sperm or lymphocytes embedded in agarose

A simple and efficient method for determining restriction fragment length polymorphism types on large numbers of individuals using small samples of peripheral blood or sperm cells is described. Whole cells embedded in low gelling/melting temperature agarose were treated with a series of enzyme, detergent, and washing steps to release high molecular weight DNA that was then digested with standard restriction enzymes such as EcoRI and PstI, electrophoresed, blotted, and probed as in normal Southern analyses. The technique should be readily adaptable to any application requiring DNA from small numbers of cells for Southern analyses or pulsed field gel electrophoresis.

Neutrophils in reexpansion pulmonary edema

This study investigated the possible contribution of neutrophils to development of reexpansion pulmonary edema (RPE) in rabbits. Rabbits' right lungs were collapsed for 7 days and then reexpanded with negative intrathoracic pressure for 2 h before study, a model that creates unilateral edema in the reexpanded lungs but not in contralateral left lungs. Two hours after lung reexpansion, significant increases in lavage albumin concentration (17-fold), percent neutrophils (14-fold), and total number of neutrophils (7-fold) recovered occurred in the reexpanded lung but not in the left. After 2 h of reexpansion increased leukotriene B4 was detected in lavage supernatant from right lungs (335 +/- 33 pg/ml) compared with the left (110 +/- 12 pg/mg, P less than 0.01), and right lung lavage acid phosphatase activity similarly increased (6.67 +/- 0.35 U/l) compared with left (4.73 +/- 0.60 U/l, P less than 0.05). Neutropenia induced by nitrogen mustard (17 +/- 14 greater than neutrophils/microliters) did not prevent RPE, because reexpanded lungs from six neutropenic rabbits were edematous (wet-to-dry lung weight ratio 6.34 +/- 0.43) compared with their contralateral lungs (4.97 +/- 0.04, P less than 0.01). An elevated albumin concentration in reexpanded lung lavage from neutropenic rabbits (8-fold) confirmed an increase in permeability. Neutrophil depletion before reexpansion did not prevent unilateral edema, although neutrophils were absent from lung sections and alveolar lavage fluid from neutropenic rabbits.

Ultrastructural heterogeneity of pulmonary scar adenocarcinomas: correlation with patients' survival

A prospective study of 24 pulmonary scar adenocarcinomas was conducted to evaluate a potential correlation between patients' survival, propensity to metastasize, and subtypes of pulmonary scar adenocarcinomas as determined by ultrastructural examination. Ultrastructural studies of pulmonary adenocarcinomas have shown three types of cells: mucus, Clara, and alveolar, with neoplasms exhibiting these cellular components either singly or in combination. Previous studies of adenocarcinomas have revealed that tumors with Clara and alveolar cell differentiation have a better prognosis than those with a mucus cell component. The present study emphasizes clinico-pathologic correlations and indicates that pulmonary scar adenocarcinomas represent a heterogeneous group with a similar cell distribution as has been found in other pulmonary adenocarcinomas. The previously established correlation between cell types and survival remains true in this group of pulmonary adenocarcinomas. Light microscopic growth patterns and special stains (PAS and mucicarmine) were not predictable in identifying the different varieties of pulmonary adenocarcinomas.

Re-expansion pulmonary edema. A potential role for free radicals in its pathogenesis

Re-expansion pulmonary edema (RPE) has been attributed to decreased lung interstitial pressures from a variety of mechanisms. Because some recent studies have implicated mechanisms that increase microvascular permeability in RPE, we tested whether the edema were due to free radical generation during re-expansion and reoxygenation of the collapsed lung. We used a rabbit model of RPE to test the effects of intracellular (dimethylthiourea) or extracellular (catalase) oxygen metabolite scavengers. Allopurinol was administered separately to determine whether xanthine oxidase was an important source of superoxide in this model. Edema was quantitated both gravimetrically and histologically, and lung xanthine oxidase activity was measured using a sensitive fluorometric assay with pterin as substrate. The results suggest indirectly that OH. or H2O2 (derived from O2-) contribute to the well-documented increase in lung permeability in RPE because dimethylthiourea, dimethylthiourea plus catalase, or catalase alone inhibited the edema to various degrees. Further, we observed histologically that increased numbers of neutrophils were present in re-expanded lungs and that neutrophil infiltration appeared to be diminished by antioxidant administration. Allopurinol did not decrease the edema, because xanthine oxidase activity in rabbit lung tissue is extremely low. We speculate that free radical generation in lung tissue contributes to the pathogenesis of RPE, although reinitiation of lung perfusion and ventilation requires a rapid change in intrathoracic pressure.

Improvement in bronchial squamous metaplasia in smokers treated with folate and vitamin B12. Report of a preliminary randomized, double-blind intervention trial

To test whether changes in folate and vitamin B12 nutrition modify the severity of potentially premalignant lesions identified by cytology in sputum samples of smokers, we conducted a randomized, controlled prospective intervention trial in smokers with bronchial squamous metaplasia. Seventy-three men with a history of 20 or more pack-years of cigarette smoking who had metaplasia on one or more sputum samples were stratified according to smoking level and randomly assigned to four months' treatment with either placebo or 10 mg of folate plus 500 micrograms of hydroxocobalamin. Direct cytological comparison of the two groups after four months showed significantly greater reduction of atypia in the supplemented group. This provides preliminary evidence that atypical bronchial squamous metaplasia may be reduced by supplementation with folate and vitamin B12. However, the significance of these findings is tempered by substantial spontaneous variation in sputum cytologies, the small study population, the short duration of the trial, and the supraphysiological doses of folate and B12 used. The results should not be construed as pointing to a potential way of preventing lung cancer in individuals who continue to smoke or as supporting self-medication with large doses of folate or B12 by smokers.

Mineral content of bone: measurement by energy subtraction digital chest radiography

Several methods are presently available for measuring the mineral content of bone. Those in widespread use include dual-photon absorptiometry and quantitative CT. The feasibility of using dual-energy digital chest radiography for determination of the mineral content of posterior ribs on digital chest images was studied by using a prototype unit. The results showed a significant difference in the mineral density of the posterior ribs of control subjects and those of patients who had osteoporosis (251.1 +/- 36 mg Ca2+/cm2 of rib vs 158.8 +/- 48 mg Ca2+/cm2, p less than or equal to .01) and a close correlation with values obtained by dual-photon absorptiometry of the lumbar spine (r = .77). The results suggest that this technique can provide an accurate assessment of the presence or absence of osteoporosis.

Calcification in pulmonary nodules: detection with dual-energy digital radiography

The authors undertook a clinical study to determine the accuracy of dual-energy digital radiography in revealing nodule calcification because calcification in a pulmonary nodule almost excludes the possibility of malignancy. Over a 6-month period, 61 patients with pulmonary nodules (less than or equal to 3 cm) or masses (greater than 3 cm) were examined on a prototype scanned projection unit using a dual-energy detector. In 49 of 61 patients, nodules were noncalcified, and in 12, they were calcified. In 57 patients, the benignancy or malignancy of nodules was established beyond reasonable doubt by pathologic confirmation in 38 and by strong inference in 19 (four patients with noncalcified solitary pulmonary nodules either refused further investigation or surgery or their follow-up was too short to permit exclusion of malignancy). Dual-energy radiography was found to be highly accurate in assessing the presence or absence of calcification in pulmonary nodules and thus in determining their benignancy or possible malignancy.

Germline VH genes in an a3 rabbit not typical of any one VHa allotype

We have undertaken investigations in the rabbit of VH genes that may be responsible for the observations of VHa allotypes unexpected from an animal's pedigree (latent allotypes). A short cDNA probe was prepared and shown to be specific for VHa2 mRNA. Southern analyses with short and large probes were unrevealing but screening of a lambda phage library from a VHa3-expressing animal identified a number of unusual genes. These VH genes are remarkable in that they are far closer to one another in the genome (in one case 3085 bps) than VH genes reported in mouse or man, they are highly homologous over long stretches of sequence, and they encode proteins not typical of any one VHa allotype. Proteins similar to the sort encoded by these genomic V-regions may explain some of the observations of latent allotype. Our data suggest that the allelic behavior of VHa allotypes is not due to allelism of a regulatory mechanism that acts upon identical VH genes in rabbits of different VHa phenotypes.

Germline VH genes in an a3 rabbit not typical of any one VHa allotype

We have undertaken investigations in the rabbit of VH genes that may be responsible for the observations of VHa allotypes unexpected from an animal's pedigree (latent allotypes). A short cDNA probe was prepared and shown to be specific for VHa2 mRNA. Southern analyses with short and large probes were unrevealing but screening of a lambda phage library from a VHa3-expressing animal identified a number of unusual genes. These VH genes are remarkable in that they are far closer to one another in the genome (in one case 3085 bps) than VH genes reported in mouse or man, they are highly homologous over long stretches of sequence, and they encode proteins not typical of any one VHa allotype. Proteins similar to the sort encoded by these genomic V-regions may explain some of the observations of latent allotype. Our data suggest that the allelic behavior of VHa allotypes is not due to allelism of a regulatory mechanism that acts upon identical VH genes in rabbits of different VHa phenotypes.

Black thyroid: clinical manifestations, ultrastructural findings, and possible mechanisms

Ultrastructural examination of three black thyroid glands showed lysosomal accumulations of lipofuscin-like pigment and granular electron-dense material in association with 1) a minocycline-associated black thyroid with normal thyroid function; 2) a minocycline-associated black thyroid with a significant inflammatory component, fibrosis, and primary hypothyroidism; and 3) a black thyroid gland with no exposure to minocycline. The deposition of the pigments in the three cases resulted in macroscopically recognizable black thyroid glands. It is speculated that an imbalance in lysosomal function accounts for this abnormality. The glandular hypofunction documented in case 2 is unique and confirms the need to monitor function carefully in patients who are receiving minocycline. In one case electrondense deposits were identified in the thyroid gland interstitium.

The structural and genetic basis for expression of normal and latent VHa allotypes of the rabbit

The immunoglobulin heavy chain variable regions of the rabbit are unusual in having genetically controlled, serologically detectable alternative forms, the VHa allotypes, as well as minor VH allotypes of the x, y and w groups. New insights into the probable structural basis for the VHa allotypes have come from re-examination of earlier protein sequence data in the light of newly deduced protein sequences derived from sequencing cloned cDNAs and genomic DNAs encoding VH regions. Here we review this sequence information, and define the allotype-correlated differences at seven positions in framework region 1 and 10 positions in framework region 3 that may lead to the serologically detectable allotypic determinants (allotopes). Most alternative amino acids at allotype-correlated positions can be derived from each other by single-base changes. Thus somatic mutations and/or gene conversion-like events must be considered along with other serological and genetic explanations for various reported observations of the production of latent VHa allotypes. The proximity of rabbit VH genes (approximately 3 kb apart) might enhance the likelihood of conversion-like events in both germline and somatic cells.

Autonomous cholesterol biosynthesis in murine hepatoma. A receptor defect with normal coated pits

These studies indicate that autonomous cholesterol biosynthesis by hepatocellular carcinoma may result from absent or defective receptors for chylomicron remnants on the surface of the malignant hepatocytes. In vivo, DAB2 hepatoma or liver were perfused with chylomicron remnants labeled with tritiated palmitic acid. Normal liver had chylomicron remnant uptake/gm tissue that was ten times that of hepatoma. In vitro studies using isolated hepatocytes and cultured DAB2 hepatoma cells showed similar results. Uptake of chylomicron remnants labeled with 3H-palmitic acid by normal hepatocytes during a 4-hour period was ten times that of hepatoma cells. Both in vivo and in vitro differences were statistically highly significant (P less than 0.005). Since many surface receptors are related to the coated pits, the cellular membranes of both neoplastic and normal liver cells were examined by electron microscopy. Coated pits were present in both the hepatoma and normal liver cells and occupied 2.61% and 2.65% of the cell surface, respectively. The defective uptake of chylomicron remnants by DAB2 hepatoma appears to be related to the chylomicron remnant receptor and not to the coated pit-internalization mechanism.

Abnormal lactate dehydrogenase isoenzyme pattern in a critically ill patient

We have described a patient who had an abnormal isoenzyme of lactate dehydrogenase in both serum and tissue. The presence of LD6 is indicative of a poor prognosis. Some of the biochemical characteristics of the isoenzyme are (1) LD6 is not an artifact, (2) it contains an M subunit but not an H subunit, and (3) it is not an immunoglobulin complex. We believe LD6 may arise during episodes of severe shock as lysosomes rupture and is either a previously sequestered lysosomal LD or is a lysosomal modification of LD5.

Spontaneous primary dissecting coronary artery aneurysm. Report of two cases

Two cases of dissecting aneurysm of the left main stem and left anterior descending coronary arteries are presented. Both cases were discovered during routine medicolegal death investigations. Unusual aspects of one of our cases include the history of antecedent trauma and the precise identification of an intimal tear.

Small cell carcinoma of the esophagus: evidence for a unified histogenesis

Four cases of small cell carcinoma of the esophagus, histologically indistinguishable from oat cell carcinoma of the lung, were studied by electron microscopy. Three were composed largely of small cells with neurosecretory granules characteristic of APUD (amine precursor uptake and decarboxylation) cells. Two of these three cases also contained foci of squamous or glandular differentiation, or both. The fourth case was classified as reserve cell carcinoma with squamous differentiation, since the tumor cells were devoid of neurosecretory granules but contained desmosomes and bundles of intracytoplasmic tonofilaments. The evidence provided by these four cases and also by the 48 cases previously reported in the literature supports our hypothesis that a totipotent primitive cell serves as the common precursor for squamous cell, adeno-, and small cell carcinoma of the esophagus. The latter can be subdivided into oat cell and reserve cell carcinomas, both having the propensity for further squamous and glandular differentiation. The hypothesis can also be applied to lung cancer.

Complete sequence of a cloned cDNA encoding rabbit secreted mu-chain of VHa2 allotype: comparisons with VHa1 and membrane mu sequences

The complete sequence of a cDNA clone (pmu3) encoding a secreted IgM heavy chain from a rabbit of VHa2 allotype has been determined. Comparison of the nucleic acid and amino acid sequences with a comparable mouse mu-chain shows unusually high homologies of the sequences of the fourth domains and secretory portions of the molecules (80 to 90% vs 56 to 73% for the other domains). This high degree of homology is also seen with the sequences of the fourth domain and secreted terminus of human mu-chain. The DNA sequence of a second cDNA clone encoding the membrane form of rabbit IgM is approximately 90% homologous with the mouse and human coding sequences for the membrane terminus, and there is 98 and 97% amino acid sequence homology. We found an unusually long (156 base pair) 5' untranslated region in clone pmu3 and discovered that 105 bases at the 5' end were complementary to the terminal portion of the CH4 domain of our mu sequence. Southern blotting analyses and the finding of a 13 base pair segment in rabbit genomic V region DNA that is homologous to the complementary strand of a segment of the CH4 of rabbit mu strongly suggests that this extended sequence resulted from a reverse transcriptase "hooking error". We have also obtained and sequenced another cDNA clone from a VHa1 cDNA library. Comparison of the V region of clone pmu3 from VHa2 with the 117 available positions of a1 DNA sequence shows 25 differences, nine of which are in allotype-associated codons. There is also a two-codon deletion in the VHa1 compared to VHa2 in the third framework region that may contribute to allotypic differences. Development of VHa allotype-specific probes, now in progress, is complicated by the fact that most of the allotype-associated amino acids of a1, a2, and a3 can be derived from each other by single base changes.

Genetics and expression of kappa-type light chains in Basilea rabbits

In contrast to rabbits of b4, b5, b6, and b9 allotypes whose serum immunoglobulins (Igs) are predominantly composed of kappa-type light chains, rabbits of the mutant Basilea strain have serum Igs that are largely of lambda type. We prepared several antisera that recognized a minor K2 (bas) light chain that is produced by Basilea rabbits. With these antisera we identified the K2 (bas) isotype in the serum of the original b9/b9 male rabbit whose offspring displayed the Basilea mutant phenotype. It was present in one half of his nonmutant offspring which inherited b9 from him and another b allotype from their mothers. Breeding was conducted both in Basel and at the NIH to develop and maintain colonies of mutant Basilea strain rabbits. The data obtained during colony development confirm that the trait of expression of the bas allotype maps to the same genetic region (b locus) that is known to control the allelic b allotypes b4, b5, b6 and b9. Homozygotes or heterozygotes of b4, b5 or b6 allotype (bb/bb) were mated with homozygous bbas / bbas rabbits to produce F1s , and then F2s as well as progeny of backcrosses to both homozygous parental types (bb/bb and bbas / bbas ) were produced. The bas allotype segregates as an allele (or pseudoallele ) at the b locus although there was a deficiency in recovery of homozygous bas offspring in both the F2 and backcross matings to bbas / bbas parental type in the NIH colony. This selective deficiency may reflect a deleterious effect on survival of homozygous bas progeny.

Complete sequence of a cloned cDNA encoding rabbit secreted mu-chain of VHa2 allotype: comparisons with VHa1 and membrane mu sequences

The complete sequence of a cDNA clone (pmu3) encoding a secreted IgM heavy chain from a rabbit of VHa2 allotype has been determined. Comparison of the nucleic acid and amino acid sequences with a comparable mouse mu-chain shows unusually high homologies of the sequences of the fourth domains and secretory portions of the molecules (80 to 90% vs 56 to 73% for the other domains). This high degree of homology is also seen with the sequences of the fourth domain and secreted terminus of human mu-chain. The DNA sequence of a second cDNA clone encoding the membrane form of rabbit IgM is approximately 90% homologous with the mouse and human coding sequences for the membrane terminus, and there is 98 and 97% amino acid sequence homology. We found an unusually long (156 base pair) 5' untranslated region in clone pmu3 and discovered that 105 bases at the 5' end were complementary to the terminal portion of the CH4 domain of our mu sequence. Southern blotting analyses and the finding of a 13 base pair segment in rabbit genomic V region DNA that is homologous to the complementary strand of a segment of the CH4 of rabbit mu strongly suggests that this extended sequence resulted from a reverse transcriptase "hooking error". We have also obtained and sequenced another cDNA clone from a VHa1 cDNA library. Comparison of the V region of clone pmu3 from VHa2 with the 117 available positions of a1 DNA sequence shows 25 differences, nine of which are in allotype-associated codons. There is also a two-codon deletion in the VHa1 compared to VHa2 in the third framework region that may contribute to allotypic differences. Development of VHa allotype-specific probes, now in progress, is complicated by the fact that most of the allotype-associated amino acids of a1, a2, and a3 can be derived from each other by single base changes.

Ultrastructural subtypes of pulmonary adenocarcinoma. A correlation with patient survival

A retrospective study of 34 patients (33 male and one female) was conducted to evaluate a potential correlation between patient survival, propensity to metastasize and specific subtypes of pulmonary adenocarcinomas as determined by ultrastructural examination. Previous electron microscopic studies of pulmonary adenocarcinomas have demonstrated proliferations of three types of cells: mucus, Clara, and alveolar cells. Specific ultrastructural markers of these cell types were assessed in the 34 cases. All cases in this study had a light microscopic diagnosis of adenocarcinoma originating in the pulmonary parenchyma and a follow-up of at least one year. Features such as patient survival time, extent of metastatic involvement, response to therapy, and overall tumor behavior were compared in reference to the cell of origin, in an effort to try to elucidate if such ultrastructural subclassification lent itself to any clinical correlations. Light microscopic growth patterns and special stains were not found to distinguish these neoplasms histogenetically, emphasizing the important role of electron microscopy for an accurate classification.

Nucleotide sequence of a rabbit IgG heavy chain from the recombinant F-I haplotype

We report the sequence of a cDNA encoding a rabbit immunoglobulin gamma heavy chain of d12 and e14 allotypes with high homology to partial cDNA sequences from rabbits of d11 and e15 allotypes. The encoded rabbit protein shows homologies with human (68-70%) and mouse (60-63%) gamma chains. The nucleotide sequence homologies of the CH domains range from 76-84% with human and 64-76% with mouse sequences. Comparison of the portion of VH encoding amino acid positions 34-112 with a previously determined VH sequence of the same allotype shows high conservation of sequences in the second and third framework segments but more marked differences both in length and encoded amino acids of the second and third complementarity-determining regions (CDRs). We also found a high degree of homology with a human genomic V-region, VH26 (77%) and a remarkable similarity between rabbit and human second CDR sequences and human genomic D minigenes. These results provide additional evidence that D minigene sequences share information with the CDR2 portion of VH regions.

Multiple sclerosis and hypertrophic demyelinating peripheral neuropathy

A combination of multiple sclerosis (MS) and hypertrophic demyelinating neuropathy has been reported in a few autopsy studies. We are reporting a unique case of such a combination, which was proved by the sural nerve biopsy. A patient with classical MS on history and findings had areflexia and sensory abnormalities in stocking distribution. The nerve conduction study showed marked abnormalities indicative of demyelinating neuropathy, and sural nerve biopsy was typical of hypertrophic demyelinating neuropathy.