IgG4-related disease in a multi-ethnic community: clinical characteristics and association with malignancy

BACKGROUND

Immunoglobulin-G4-related disease (IgG4-RD) is a recently recognized fibro-inflammatory condition that can affect multiple organs. Despite growing interest in this condition, the natural history and management of IgG4-RD remain poorly understood.

AIM

To describe the clinical characteristics, treatment and outcomes of IgG4-RD in a multi-ethnic UK cohort, and investigate its possible association with malignancy.

DESIGN

Retrospective analysis of case-note and electronic data.

METHODS

Cases were identified from sub-specialty cohorts and a systematic search of an NHS trust histopathology database using 'IgG4' or 'inflammatory pseudotumour' as search terms. Electronic records, imaging and histopathology reports were reviewed.

RESULTS

In total, 66 identified cases of IgG4-RD showed a similar multi-ethnic spread to the local population of North West London. The median age was 59 years and 71% of patients were male. Presenting symptoms relating to mass effect of a lesion were present in 48% of cases and the mean number of organs involved was 2.4. Total of 10 patients had reported malignancies with 6 of these being haematological. 83% of those treated with steroids had good initial response; however, 50% had relapsing-remitting disease. Rituximab was administered in 11 cases and all achieved an initial serological response. Despite this, seven patients subsequently relapsed after a mean duration of 11 months and four progressed despite treatment.

CONCLUSIONS

We report a large UK-based cohort of IgG4-RD that shows no clear ethnic predisposition and a wide range of affected organs. We discuss the use of serum IgG4 concentrations as a disease marker in IgG4-RD, the association with malignant disease and outcomes according to differing treatment regimens.

Treatment-limiting renal tubulopathy in patients treated with tenofovir disoproxil fumarate

OBJECTIVES

Tenofovir disoproxil fumarate (TDF) is widely used in the treatment or prevention of HIV and hepatitis B infection. TDF may cause renal tubulopathy in a small proportion of recipients. We aimed to study the risk factors for developing severe renal tubulopathy.

METHODS

We conducted an observational cohort study with retrospective identification of cases of treatment-limiting tubulopathy during TDF exposure. We used multivariate Poisson regression analysis to identify risk factors for tubulopathy, and mixed effects models to analyse adjusted estimated glomerular filtration rate (eGFR) slopes.

RESULTS

Between October 2002 and June 2013, 60 (0.4%) of 15,983 patients who had received TDF developed tubulopathy after a median exposure of 44.1 (IQR 20.4, 64.4) months. Tubulopathy cases were predominantly male (92%), of white ethnicity (93%), and exposed to antiretroviral regimens that contained boosted protease inhibitors (PI, 90%). In multivariate analysis, age, ethnicity, CD4 cell count and use of didanosine or PI were significantly associated with tubulopathy. Tubulopathy cases experienced significantly greater eGFR decline while receiving TDF than the comparator group (-6.60 [-7.70, -5.50] vs. -0.34 [-0.43, -0.26] mL/min/1.73 m²/year, p < 0.0001).

CONCLUSIONS

Older age, white ethnicity, immunodeficiency and co-administration of ddI and PI were risk factors for tubulopathy in patients who received TDF-containing antiretroviral therapy. The presence of rapid eGFR decline identified TDF recipients at increased risk of tubulopathy.

An atypical cutaneous presentation of vasculitis with features of Churg-Strauss syndrome, associated with anti-neutrophil cytoplasmic antibodies and anti-glomerular basement membrane antibodies

We report the case of a 59-year-old woman who presented with a persistent papular and nodular cutaneous eruption and new-onset asthma, with normal renal function but persistent haematuria and proteinuria. Investigations revealed eosinophilia, both antineutrophil cytoplasmic antibodies and antiglomerular basement membrane antibodies on serological testing (double-positive vasculitis), and a focal necrotizing glomerulonephritis on renal biopsy. Histological examination of a skin biopsy showed a dense neutrophilic infiltrate with focal fibrinoid necrosis and few eosinophils. The clinical and pathological features suggested a double-positive vasculitis/Churg-Strauss overlap syndrome presenting with a predominantly neutrophilic dermatosis. Specific cutaneous features in patients with double-positive vasculitis have not been documented previously. The patient has responded extremely well to immunosuppressive treatment and her disease is currently in remission.

Impact of new dialysis solutions on peritonitis rates

Peritonitis remains a major cause of morbidity among patients on peritoneal dialysis (PD), yet there is little information about the effect of new biocompatible dialysis solutions on peritonitis rates and treatment. In our unit, information on each peritonitis episode is prospectively collected. Since 2003, bicarbonate/lactate dialysate has been gradually introduced for new patients and for patients experiencing abdominal pain with conventional lactate solutions. From 2002 to 2005, data from 121 episodes of peritonitis (71 automated PD and 50 continuous ambulatory PD) were analyzed; 107 episodes occurred in patients using standard lactate dialysate and 14 episodes in patients using bicarbonate/lactate solution. Patients using bicarbonate/lactate had a significantly lower peritonitis rate of 1 per 52.5 patient-months compared to those using standard lactate dialysate (1 per 26.9 patient-months) (P=0.0179). Response to treatment, however, was not affected by the type of dialysate; cure rates (71.4 and 69.1%, respectively) and recurrence rates (21.4 and 15.8%, respectively) were not significantly different. Catheter removal was required in three (21.4%) patients using bicarbonate/lactate and 23 (22.4%) patients using lactate solution. Use of biocompatible dialysate appears to reduce the peritonitis rate by 50%, although this has to be confirmed in a randomized study. The type of dialysate, on the other hand, does not affect response to treatment.

Characterization of autoantibodies from patients with Goodpasture's disease using a resonant mirror biosensor

Goodpasture's disease is characterized by the binding of IgG autoantibodies to the glomerular basement membrane, leading to glomerular inflammation. The autoantigen has been identified as the noncollagenous domain of the alpha3 chain of type IV collagen (alpha3(IV)NC1). We have used the IAsys resonant mirror biosensor to analyse the extent and affinity of binding of anti-GBM antibodies from sera of patients to purified alpha3(IV) NC1. alpha3(IV) NC1 monomers were immobilized to a carboxylate cuvette, with the simultaneous use of a control well. The binding of serum from patients with Goodpasture's disease (n = 12), normal controls (n = 14) and disease controls with vasculitis (n = 14) was analysed. Antibody binding was detected in sera from all patients with Goodpasture's disease but not from controls. IAsys measurements of binding correlated with antibody levels assessed by the standardized ELISA used for clinical assays. Both ELISA and biosensor measurements showed declining antibody levels in serial serum samples from treated patients; however, the biosensor detected antibody recrudescence when ELISA remained negative. Autoantibodies from patients' serum had average affinity constants (Kd) of 6.5 x 10-11M to 52.07 x 10-10M, as determined by an inhibition assay, indicating high affinity. Sips analysis showed that the antibody response was relatively homogeneous (values of 0.46-1). Biosensor techniques can therefore be used to detect and characterize anti-GBM antibodies in serum from patients, with high sensitivity and without need for antibody purification. This technique may be useful in diagnosis and monitoring of patients with Goodpasture's disease, and may be applicable to other autoantibody mediated diseases.

Long-term outcome of anti-glomerular basement membrane antibody disease treated with plasma exchange and immunosuppression

BACKGROUND

Anti-glomerular basement membrane (GBM) antibody disease is an autoantibody-mediated disorder that usually presents as rapidly progressive glomerulonephritis, often with pulmonary hemorrhage (the Goodpasture syndrome). It is reported that patients with severe renal failure do not generally recover renal function.

OBJECTIVE

To examine the long-term outcome of severe anti-GBM antibody disease.

DESIGN

Retrospective review of patients treated for confirmed anti-GBM antibody disease over 25 years.

SETTING

A tertiary referral center in the United Kingdom.

PATIENTS

71 treated patients with anti-GBM antibody disease.

INTERVENTION

All patients received plasma exchange, prednisolone, and cyclophosphamide.

MEASUREMENTS

Patient and renal survival, renal histology, and antibody levels.

RESULTS

Patients who presented with a creatinine concentration less than 500 micromol/L (5.7 mg/dL) (n = 19) had 100% patient survival and 95% renal survival at 1 year and 84% patient survival and 74% renal survival at last follow-up. In patients who presented with a creatinine concentration of 500 micromol/L or more (>/=5.7 mg/dL) (n = 13) but did not require immediate dialysis, patient and renal survival were 83% and 82% at 1 year and 62% and 69% at last follow-up. In patients who presented with dialysis-dependent renal failure (n = 39), patient and renal survival were 65% and 8% at 1 year and 36% and 5% at last follow-up. All patients who required immediate dialysis and had 100% crescents on renal biopsy remained dialysis dependent.

CONCLUSIONS

Patients with the Goodpasture syndrome and severe renal failure should be considered for urgent immunosuppression therapy, including plasma exchange, to maximize the chance of renal recovery. Patients needing immediate dialysis are less likely to recover.

Nephrotoxicity of intravenous immunoglobulin

Individual case reports have documented nephrotoxicity of intravenous immunoglobulin (IVIG) preparations, but the true incidence of renal dysfunction is unknown and many data sheets do not include renal impairment as a side-effect of these preparations. We determined the incidence of renal impairment in an unselected cohort of patients receiving two different preparations of IVIG over 20 months, administering 287 courses of IVIG to 119 patients for a variety of indications, including thrombocytopenia, systemic lupus erythematosis, neuropathy, Guillain-Barre syndrome and infections. Two different preparations of IVIG were used, Vigam (BPL) and Sandoglobulin (Novartis), which differ in the concentration of sucrose added as a stabilizer. Eight patients showed deterioration in renal function (6.7%), and in two, no renal recovery occurred (1. 7%). There were no significant differences in the patient characteristics or dose or preparation of IVIG administered to those patients with or without changes in serum creatinine. There was no association between the amount of sucrose in the IVIG and development of renal failure. IVIG (regardless of the sucrose content) is associated with renal impairment which may be irreversible, with a maximum incidence of 6.7%. All patients should have their renal function monitored during the use of IVIG.

The tyrosine phosphatase SHP-1 is a negative regulator of osteoclastogenesis and osteoclast resorbing activity: increased resorption and osteopenia in me(v)/me(v) mutant mice

Naturally occuring inactivating mutations of the Src homology 2 (SH2) domain-containing tyrosine phosphatase 1 (SHP-1) in mice give rise to the motheaten (me) phenotype. me/me mice have multiple hematopoietic abnormalities, suggesting that this phosphatase plays an important role in hematopoiesis. SHP-1 binds to and is activated by several hematopoietic surface receptors, including the colony-stimulating factor type 1 receptor. We have examined the role of SHP-1 in osteoclastogenesis and osteoclast function using mice with the viable motheaten (me(v)/me(v)) mutation, which has markedly decreased SHP-1 activity. Histomorphometric analysis of 6-week-old me(v)/me(v) mice and control littermates showed a marked osteopenia with an increase in bone resorption indices. The number of formed osteoclast-like cells (OCLs) in cocultures of me(v)/me(v) hematopoietic cells with normal osteoblasts was significantly increased. In contrast, the number of OCLs formed in the coculture of normal bone marrow cells with the me(v)/me(v) osteoblasts was not significantly different from controls. The bone-resorbing activity of me(v)me(v) OCLs and authentic osteoclasts was also found to be increased. Finally, Western blotting of proteins from me(v)/me(v) and control OCLs revealed an overall increase in tyrosine phosphorylation in the me(v)/me(v) lysates. These in vivo and in vitro results suggest that SHP-1 is a negative regulator of bone resorption, affecting both the formation and the function of osteoclasts.

Urological complications after kidney-pancreas transplantation

PURPOSE

Urological complications are common after kidney-pancreas transplantation. Predictors of urological complication after transplantation have not been established. We studied the impact of urological complications on allograft function. In addition we evaluated age at transplantation, diabetic years before transplantation and preoperative bladder function as predictors of allograft pancreatitis, postoperative retention and urine leaks.

MATERIALS AND METHODS

Urological complications in 65 cases (38 men, 27 women, mean diabetic years 21 +/- 6, mean age 33 +/- 7 years) who had transplants between December 1987 and January 1995 were reviewed. Preoperative urodynamics in 50 patients (77%) and voiding cystourethrogram in 40 (62%) were analyzed. Kidney-pancreas transplantation was completed using bladder drainage techniques.

RESULTS

Mean followup was 44 +/- 27 months (median 40, range 1 to 93). Urological complications in 51 patients (79%) included urinary tract infection in 59%, hematuria in 26%, allograft pancreatitis in 19%, duodenal leaks in 17%, ureteral lesions in 9% and urethral lesions in 6%. Eleven duodenal leaks (8 leaks in less than 1 month) required surgical treatment. Nine leaks recurred in 7 patients. Allograft pancreatitis occurred 32 times (range 1 to 9) in 12 patients. Three patients had ureteral obstruction and 3 had ureteral leaks. Preoperative urodynamics included detrusor hyperreflexia in 8 patients, detrusor areflexia in 19, indeterminate in 5 and normal in 18. The 1-year patient, kidney and pancreatic allograft survival rates were 92, 91 and 86%; 2-year survival rates were 89, 88 and 80%, and 5-year survival rates were 61, 59 and 55%, respectively.

CONCLUSIONS

Urological complications were common after transplantation but did not adversely affect allograft survival in our series. Age at transplantation, diabetic years preceding transplantation and preoperative bladder function were not significantly correlated with allograft pancreatitis, postoperative urinary retention or urine leaks. A prospective analysis of postoperative bladder function should be completed to improve understanding and possibly reduce morbidity of urological complications after transplantation.

Colony-stimulating factor-1 induces cytoskeletal reorganization and c-src-dependent tyrosine phosphorylation of selected cellular proteins in rodent osteoclasts

Colony-stimulating factor-1 (CSF-1) stimulates motility and cytoplasmic spreading in mature osteoclasts. Therefore, we examined the cellular events and intracellular signaling pathways that accompany CSF-1-induced spreading in normal osteoclasts. To explore the role c-src plays in these processes, we also studied osteoclasts prepared from animals with targeted disruption of the src gene. In normal osteoclasts, CSF-1 treatment induces rapid cytoplasmic spreading, with redistribution of F-actin from a well-delineated central attachment ring to the periphery of the cell. CSF-1 increases membrane phosphotyrosine staining in osteoclasts and induces the phosphorylation of several cellular proteins in cultured, osteoclast-like cells, including c-fms, c-src, and an 85-kD Grb2-binding protein. Src kinase activity is increased threefold after CSF-1 treatment. In src- cells, no attachment ring is present, and CSF-1 fails to induce spreading or a change in the pattern of F-actin distribution. Although c-fms becomes phosphorylated after CSF-1 treatment, the 85-kD protein is significantly less phosphorylated in src- osteoclast-like cells. These results indicate that c-src is critical for the normal cytoskeletal architecture of the osteoclast, and, in its absence, the spreading response induced by CSF-1 is abrogated, and downstream signaling from c-fms is altered.

Mapping B cell epitopes in Goodpasture's disease

The target antigen of the pathogenic autoantibodies in Goodpasture's disease is the noncollagenous domain of the alpha 3 chain of type IV collagen. A panel of membrane-bound peptides was used to identify antibody-binding regions within the protein, and the significance of the binding by inhibition studies using soluble peptides, and by a structural analysis of the antigen, was confirmed. A total of 117 overlapping 12-mer peptides spanning the entire antigen was simultaneously synthesized as individual spots on a cellulose membrane. All nine patients' sera bound to the membrane, with a conserved pattern of peptides recognized by all sera. Inhibition studies were performed using a panel of overlapping 20-mer peptides, also spanning the entire antigen. Peptides from the regions that bound IgG were able to inhibit the binding of autoantibodies to native antigen. Predictions of the secondary structure of the noncollagenous domain of the alpha 3 chain of type IV collagen were performed by a conventional hydropathy plot and by multiple alignment of homologous alpha chains of type IV collagen and comparison with a structural data base. The core peptides binding and inhibiting Goodpasture's antibodies were predicted to be surface exposed and antigenic. Thus, the conformational epitope(s) of the Goodpasture antigen can be mapped using linear peptides.

Modified pudendal-thigh flap for correction of penoscrotal transposition

OBJECTIVES

In patients with penoscrotal transposition, an occasional postoperative problem has been a deficiency of skin on the proximal penile shaft that results in penoscrotal fusion and tethering.

METHODS

We describe a new operation using a modified neurovascular pudendal-thigh flap for correction of incomplete penoscrotal transposition.

RESULTS

This procedure has been used in 6 children, and an excellent cosmetic and functional result has been achieved in each patient.

CONCLUSIONS

The flaps provide a reliable blood supply, maintain normal innervation, and correct the problem of postoperative penoscrotal fusion and tethering. This technique preserves sufficient penile skin for a tension-free second-stage urethroplasty.

Hypertension after surgical management of renal duplication associated with an upper pole ureterocele

PURPOSE

Duplicated upper pole systems associated with a ureterocele frequently have areas of segmental renal dysplasia. Since dysplasia has been related to the development of renin mediated hypertension, we hypothesized that preservation of functional upper pole moieties may result in an increased incidence of high blood pressure.

MATERIALS AND METHODS

We evaluated 115 patients with a history of renal duplication and an ipsilateral upper pole ureterocele. Patients were separated into group 1-nonfunctional upper pole managed by partial nephrectomy, group 2-functional upper pole moiety managed by partial nephrectomy and group 3-functional upper pole moiety managed by a nephron sparing procedure. All charts were reviewed for hypertension, febrile urinary tract infection, vesicoureteral reflux and renal scarring.

RESULTS

At a median followup age of 15 years (range 1 to 33) hypertension developed in 13 of the 115 patients (11%), including 8 of the 87 (9%) with nonfunctional upper pole systems managed by partial nephrectomy, 1 of the 12 (8%) with a functional upper pole moiety managed by partial nephrectomy and 4 of the 16 (25%) with a functional upper pole system managed by an upper pole salvage procedure. Statistical evaluations failed to reveal any relationship between hypertension and preservation of the upper pole system or between hypertension and vesicoureteral reflux. Rather, elevation in blood pressure was found to be related to development of a renal scar after a febrile urinary tract infection.

CONCLUSIONS

Hypertension in patients with a history of renal duplication associated with a ureterocele is directly related to renal scarring.

Genitourinary neurofibromatosis mimicking posterior urethral valves

A 12-year-old boy, examined after an episode of acute urinary retention, was found to have neurofibromatosis of the bladder neck and prostatic urethra. His symptoms of bladder outlet obstruction and radiographic findings of a dilated prostatic urethra mimicked posterior urethral valves. Complete urologic investigation, including cystourethroscopy, revealed that the dilatation of the prostatic urethra was secondary to neural involvement of the external sphincter and posterior urethra without mechanical obstruction or posterior urethral valves.

Still a role for plasma exchange in rapidly progressive glomerulonephritis?

Plasmapheresis combined with immunosuppression dramatically improved the survival of patients with Goodpasture's disease in the late 1970's. The presence of circulating pathogenic autoantibodies in this disease provided a logical rationale for the use of plasma exchange therapy. Careful analysis of the response to treatment has suggested that patients presenting with a serum creatinine < 600 mumol/I have the most benefit from plasma exchange. Subsequently plasmapheresis has been tried in a variety of other nephritides, predominantly those causing rapidly progressive glomerulonephritis, with variable success. Initial studies failed adequately to distinguish patients with a number of quite distinct causes of crescentic nephritis. However it has become clear that plasma exchange significantly improves the outcome of patients with pauci-immune crescentic glomerulonephritis who present with severe renal failure requiring dialysis, but not those with less severe renal disease.

Identification of a novel 135-kDa Grb2-binding protein in osteoclasts

The tyrosine kinase receptor for macrophage colony-stimulating factor and the non-receptor tyrosine kinase c-Src play critical roles in osteoclast differentiation and function. Since the ubiquitously expressed adaptor protein Grb2 plays an important role in several tyrosine kinase signal transduction pathways, we used a filter binding assay to identify osteoclast proteins that bind to Grb2. In osteoclasts, there were three major Grb2-binding proteins, two of which, mSos and c-Cbl (p120), have been previously identified as Grb2-binding proteins in many cell types. The third protein, p135, had a restricted pattern of expression and was present at high levels in authentic osteoclasts and osteoclast-like cells formed in an in vitro co-culture system. In addition to binding Grb2 in the filter binding assay, p135 was isolated in complexes with endogenous Grb2 from osteoclast cell extracts. The association of p135 and Grb2 was dependent on an intact Src homology 3 domain and furthermore, was shown to preferentially interact with the N-terminal Src homology 3 domain of Grb2, which is similar to the interaction of mSos and Grb2 in other cell types. p135 was not recognized by antibodies against several known Grb2-binding proteins and thus may be a novel Grb2-binding protein.

c-Cbl is downstream of c-Src in a signalling pathway necessary for bone resorption

The primary defect in mice lacking the c-src gene is osteopetrosis, a deficiency in bone resorption by osteoclasts. Osteoclasts express high levels of the c-Src protein and the defect responsible for the osteopetrotic phenotype of the c-src-deficient (src-) mouse is cell-autonomous and occurs in mature osteoclasts. However, the specific signalling pathways that require c-Src expression for normal osteoclast activity have not been elucidated. We report here that the proto-oncogene product c-Cbl is tyrosine-phosphorylated in a Src-dependent manner in osteoclasts, where the two proteins colocalize on some vesicular structures. In vitro bone resorption by osteoclast-like cells (OCLs) is inhibited by both c-src and c-cbl antisense oligonucleotides. Furthermore, tyrosine phosphorylation of c-Cbl and the localization of c-Cbl-containing structures to the peripheral cytoskeleton are impaired in resorption-deficient c-src- OCLs, as well as in wild-type OCLs that have been treated with c-src antisense oligonucleotides. These results indicate that c-Cbl may act downstream of c-Src in a signalling pathway that is required for bone resorption.

Epitope analysis of the Goodpasture antigen using a resonant mirror biosensor

We have used a new technique for studying molecular interactions-a resonant mirror biosensor-to identify B cell epitopes within the Goodpasture antigen, which has recently been identified as the non-collagenous domain of the alpha 3-chain of type IV collagen (alpha 3(IV)NC1). Recombinant antigen (r-alpha 3) was immobilized onto the sensing surface of a sample cuvette, and the binding of patients' autoantibodies or a MoAb to the Goodpasture antigen was followed in real time. All patients' sera bound r-alpha 3 in this system, while control sera did not bind. A MoAb inhibited the binding of all patients' autoantibodies to r-alpha 3, from 27% to 90% (mean inhibition 60%), and patients' sera cross-inhibited the binding of each other to the antigen. Binding was inhibited by pre-incubation of autoantibody with both native sheep alpha 3(IV)NC1 and purified human alpha 3(IV)NC1 monomers. Inhibition experiments using soluble overlapping peptides from human alpha 3(IV)NC1 identified putative B cell epitopes. These results suggest that there is a major immunodominant epitope on the Goodpasture antigen, and that there is very limited heterogeneity in the autoantibody response in Goodpasture's disease. The resonant mirror biosensor can be successfully used to monitor antibody-antigen binding using polyclonal sera, and to map epitopes on autoantigens.

Congenital adrenal hyperplasia: is there an effect on penile growth?

PURPOSE

Experimental evidence in rodents suggests that prepubertal exposure to excess androgens may prematurely down regulate the penile androgen receptor and cause micropenis in adulthood. To evaluate the effect of prepubertal androgens on human penile growth we reviewed phallic development in male patients with congenital adrenal hyperplasia.

MATERIALS AND METHODS

We retrospectively reviewed the records of 12 patients with 21-hydroxylase deficiency. Stretched penile length was recorded at diagnosis and at last followup. Bone age, height and weight were recorded at each visit.

RESULTS

At diagnosis mean z-score for stretched penile length (z-score equals the number of standard deviations above or below the mean, that is z-score for micropenis equals -2.5) was 2.95 (1.23 to 4.88). Final mean z-score for stretched penile length in adulthood was -1.70 (-2.96 to 1.87). Mean decrease in z-score for diagnosis until the last followup was -4.68 (-1.08 to -6.82). Only 2 of the 12 patients (17%) had micropenis in adulthood. Notably excessive adrenal androgen production resulted in diminutive stature with median height in adulthood in the 10th percentile.

CONCLUSIONS

These findings suggest that excessive prepubertal androgen exposure due to congenital adrenal hyperplasia is associated with a reduction in adult somatic height but it does not routinely result in micropenis.

The effects of androgen administration on phallic androgen receptor expression

PURPOSE

Whether androgens down regulate the androgen receptor during penile development is controversial. We investigated the effects of androgens on penile androgen receptor expression.

MATERIALS AND METHODS

We injected prepubertal hypogonadotropic hypogonadal microphallic rats with testosterone or dihydrotestosterone. Specimens were obtained at 3 (prepuberty), 9 (puberty to early postpuberty) and 12 weeks (late postpuberty). At necropsy we compared penile size and androgen receptor expression of these animals to those of age matched nontreated hypogonadotropic hypogonadal and normal controls.

RESULTS

At age 3 weeks prepubertal androgens up regulated androgen receptor expression and significantly increased penile size compared to normal and untreated hypogonadotropic hypogonadal controls. By 9 weeks the normal down regulation of androgen receptor that occurs with maturation was present. Prepubertal androgens failed to accelerate or exaggerate the normal maturational loss of the androgen receptor. At 9 weeks penile size of normal controls and prepubertal androgen treated animals was identical. Interestingly despite down regulation of the penile androgen receptor, normal animals continued to have increases in penile size between 9 and 12 weeks, while the prepubertal androgen treated animals had no penile growth.

CONCLUSIONS

Prepubertal androgen administration in hypogonadotropic hypogonadal animals resulted in diminutive penises in adulthood. However, the decrease in penile size was not associated with an accelerated or exaggerated down regulation of the androgen receptor. This finding coupled with continued growth of the normal control penises after androgen receptor down regulation suggests that cessation of penile growth may not be solely related to down regulation of the penile androgen receptor.

Micropenis secondary to growth hormone deficiency: does treatment with growth hormone alone result in adequate penile growth?

PURPOSE

Congenital growth hormone deficiency is associated with aberrant androgen physiology and micropenis. We investigated whether treatment with growth hormone alone is adequate to restore normal phallic growth.

MATERIALS AND METHODS

In all patients the diagnosis was isolated growth hormone deficiency and micropenis, and growth hormone was the only therapy. Stretched penile length, and somatic height and weight measurements were available from diagnosis through puberty for all patients.

RESULTS

Eight patients diagnosed with isolated congenital growth hormone deficiency and micropenis were treated and evaluated. Mean z-score (number of standard deviations below mean stretched penile length) at diagnosis was -4.25 (range 3.1 to -6.6) with -2.5 representing micropenis. In adulthood mean final stretched penile length z-score was -1.73 (range -0.91 to -2.66). Seven of the 8 patients (87.5%) had stretched penile length within normal range.

CONCLUSIONS

Our findings suggest that growth hormone therapy alone can result in normal phallic size in patients with micropenis secondary to isolated congenital growth hormone deficiency.

Activation of the JAK-STAT signal transduction pathway by oncostatin-M cultured human and mouse osteoblastic cells

Oncastatin M (OSM) is one member of the leukemia inhibitory factor/interleukin-6 family of cytokines that has been shown to be a growth regulatory molecule. In osteoblastic cultures, OSM causes marked phenotypic changes and the enhanced secretion of interleukin-6. In this study, we have shown that stimulation of murine and human osteoblastic cultures and a human osteosarcoma cell line with OSM resulted in the tyrosine phosphorylation of a number of cellular proteins including members of both the Janus kinase (JAK) and signal transducer and activator of transcription (STAT) family of signaling proteins. The JAKs, a family of intracellular kinases, and the STATs, a family of transcription factors, have both previously been shown to be tyrosine phosphorylated and activated in response to various cytokines, interferons, and growth factors in cells of non-skeletal origin. Using three different sources of cells of the osteoblast lineage, we demonstrate that OSM induces a rapid but transient tyrosine phosphorylation of the three JAK family members tested, JAK1, JAK2 and Tyk2. In addition, two members of the STAT family, Stat1alpha and Stat3, are tyrosine phosphorylated in osteoblastic cells in culture in response to OSM. OSM activation of this pathway in cells of the osteoblast lineage will result in the transcription of specific genes that ultimately may be associated with osteoblast function.

Recurrent Goodpasture's disease

Goodpasture's disease is usually a monophasic illness that can be successfully treated in a large proportion of patients. Recurrent disease is rare. We report a case of Goodpasture's disease in which recurrent pulmonary hemorrhage and glomerulonephritis were observed over 12 years. Antiglomerular basement membrane autoantibody was monitored throughout this period, and we demonstrate the close association of antibody levels with disease recurrence.

The hormonal control of testicular descent

Descent of the testes is a complex event mediated by hormonal and mechanical factors. At present we hypothesize that testicular descent occurs as the result of the secretion of descendin from a normal testicle. Descendin secretion results in selective growth of the gubernacular cells. Gubernacular outgrowth results in masculinization of the inguinal canal. At the beginning of testicular descent, the patent processus migrates into the inguinal canal, transmitting intraabdominal pressure to the gubernaculum. The gubernaculum in turn applies traction to the testicle to introduce the testicle into the inguinal canal. Descent of the testes into and through the inguinal canal is an interplay between intraabdominal pressure transmitted by a patent processus vaginalis and androgen-induced gubernacular regression. Specifically, we hypothesize that androgens under control of an intact fetal hypothalamic-pituitary axis alter the viscoelastic properties of the gubernaculum. Reductions in the turgidity of the gubernaculum allow intraabdominal pressure to push the testicle into the scrotum. Functional abnormalities in any of the above factors will result in cryptorchidism.

Current concepts in the pathophysiology of testicular undescent

At present, we believe that descent of the testes within the human is a complex event mediated by both hormonal and mechanical factors. We hypothesize that descent of the testes occurs as a result of the secretion of an androgen-independent factor from a normal testis (descendin). This paracrine factor is responsible for the rapid proliferation (outgrowth) of the ipsilateral gubernaculum. The development of the gubernaculum results in creating a dilated inguinal canal, the width of which matches the testicular width. Descent of the testes through the inguinal canal is an interplay between abdominal pressure, a patent processus vaginalis, and androgen-induced gubernacular regression. We hypothesize that androgens (under control of an intact hypothalamic pituitary axis) alter the viscoelastic properties of the gubernaculum, reducing the turgidity of the gubernaculum and allowing intra-abdominal pressure to push the testis into the scrotum. Cryptorchidism can therefore result when any one or more of the involved factors malfunction.

Tyrosine phosphorylation and translocation of the c-cbl protein after activation of tyrosine kinase signaling pathways

The c-cbl protooncogene product (c-Cbl) is a 120-kDa protein that has been shown to bind to the Src homology 3 domains of various proteins, suggesting its involvement in signal transduction pathways. We identified one of the most prominent tyrosine-phosphorylated proteins in Fc gamma receptor (Fc gamma R)-stimulated macrophages to be c-Cbl. Tyrosine phosphorylation of c-Cbl occurred within 20 s after stimulation and reached maximum levels within 3-5 min. c-Cbl was also tyrosine-phosphorylated in epidermal growth factor (EGF) receptor-overexpressing cells upon EGF stimulation, in macrophages in response to CSF-1 treatment, and in v-src transformed cells. Furthermore, we found that c-Cbl associated with these kinases in vivo. In vitro, c-Cbl bound to the Src homology 3 domains of Src, Fyn, and Lyn in both unstimulated and Fc gamma R-stimulated macrophages. Examination of cells by immunofluorescence revealed that c-Cbl is diffusely distributed in the cytoplasm in both unstimulated macrophages and EGF receptor-overexpressing cells and translocated to a more specific compartment of the cell, consistent with the trans-Golgi region, following Fc gamma R clustering and EGF stimulation, respectively. These results suggest that c-Cbl is involved in the signaling pathways utilized by different types of tyrosine kinases.

Vesicourethral healing following radical prostatectomy: is it related to surgical approach?

OBJECTIVES

To explore how the occurrence of vesicourethral anastomotic strictures (bladder neck contractures [BNC]) following radical prostatectomy was dependent on these variables: postoperative urine extravasation, type of anastomosis, size of prostate, and surgical approach.

METHODS

We retrospectively reviewed 143 cases over 36 months for the occurrence of early BNC (6 to 12 months follow-up). Voiding cystourethrograms (VCUC) were performed in all patients at 3 weeks. Radical retropubic prostatectomy (RRP) with direct anastomosis was performed in 93 cases, RRP and Vest anastomosis in 35 cases, and radical perineal prostatectomy (RPP) in 15 cases.

RESULTS

The overall incidence of extravasation was 14.1%. Procedure-specific rates of incidence of extravasation were RPP 33.3%, RRP 18.1%, and radical retropubic with Vest anastomosis (Vest) 6.1%. Mean prostate weight was not significantly different between patients with or without extravasation. The anastomotic site was classified as being irregular (plicated) or smooth in appearance on the VCUG images. An irregular appearance was noted among 81% of the RRP, 42.4% of the Vest, and 40% of the RPP. Bladder neck contractures occurred in 29% of patients with Vest anastomosis, 14.1% with RRP, and none of the patients undergoing RPP. Only 1 patient in both the Vest and RRP group who experienced BNC was noted to have extravasation on VCUG at 3 weeks.

CONCLUSIONS

We have noted that the type of anastomosis (Vest traction sutures) significantly increases the likelihood of early bladder neck contracture following radical prostatectomy. The presence of contrast extravasation on the postoperative VCUG study (implying urinary extravasation) did not influence the formation of an anastomotic stricture as long as patients were maintained with catheter drainage until resolution of extravasation. The appearance of the newly constructed bladder neck on the postoperative VCUG image was not predictive of a subsequent contracture.

Combined abdominal and vaginal approach for bladder neck closure and permanent suprapubic tube: urinary diversion in the neurologically impaired woman

Chronic indwelling Foley catheter placement in the neurologically impaired patient can lead to pressure necrosis of the urethra with incontinence. We report on 2 series of patients who underwent bladder neck closure and insertion of a suprapubic catheter for this problem. Our initial group includes 4 patients who underwent 5 transvaginal procedures, of which 2 (40%) were successful. Subsequently, we modified our approach, and used a combined abdominal and transvaginal repair, which was successful in 10 consecutive patients with a followup of 6 to 40 months (mean 15.6).

Receptor tyrosine phosphatase beta is expressed in the form of proteoglycan and binds to the extracellular matrix protein tenascin

The extracellular domain of receptor type protein tyrosine phosphatase beta (RPTP beta) exhibits striking sequence similarity with a soluble, rat brain chondroitin sulfate proteoglycan (3F8 PG). Immunoprecipitation experiments of cells transfected with RPTP beta expression vector and metabolically labeled with [35S]sulfate and [35S]methionine indicate that the transmembrane form of RPTP beta is indeed a chondroitin sulfate proteoglycan. The 3F8 PG is therefore a variant form composed of the entire extracellular domain of RPTP beta probably generated by alternative RNA splicing. Previous immunohistochemical studies indicated that both RPTP beta and the extracellular matrix protein tenascin are localized in similar regions of the central nervous system. We have performed co-aggregation assays with red and green Co-vaspheres coated with tenascin and 3F8 PG, respectively, showing that the extracellular domain of RPTP beta (3F8 PG) binds specifically to tenascin. The interaction between a receptor tyrosine phosphatase and an extracellular matrix protein may have a role in development of the mammalian central nervous system.

Selenium deficiency, reversible cardiomyopathy and short-term intravenous feeding

We report the case of a patient with Crohn's disease receiving short-term postoperative parenteral nutrition supplemented with trace elements who nevertheless became selenium deficient with evidence of a cardiomyopathy. This was fully reversible with oral selenium supplementation. Current parenteral feeding regimes may not contain enough selenium for malnourished patients.

The expression of a novel receptor-type tyrosine phosphatase suggests a role in morphogenesis and plasticity of the nervous system

Analysis of the localization of receptor-type protein tyrosine phosphatase-beta (RPTP-beta) by in situ hybridization and immunocytochemistry indicates that it is predominantly expressed in the developing central nervous system (CNS). RPTP-beta is highly expressed in radial glia and other forms of glial cells that play an important role during development. The immunoreactivity localizes to the radial processes of these cells, which act as guides during neuronal migration and axonal elongation. The pattern of RPTP-beta expression changes with the progression of glial cell differentiation. In the adult, high levels of RPTP-beta are seen in regions of the brain where there is continued neurogenesis and neurite outgrowth. The spatial and temporal patterns of RPTP-beta expression suggest that this receptor phosphatase plays a role in morphogenesis and plasticity of the nervous system.

Nonoperative management of blunt pediatric major renal trauma

Although algorithms exist for the management of renal trauma in adults, guidelines have not been established in children. Of 1,175 patients entered into our Trauma Registry between 1987 and 1991, 61 (5.2%) presented with gross or microscopic hematuria. Eight of the 58 patients (13.8%) who had blunt abdominal trauma had major renal injuries. Gross hematuria (n = 10) was a significant predictor of major renal injury (n = 5) (p < 0.001). All 3 patients with microscopic hematuria and a major renal injury also had evidence of multisystem trauma. Admission blood pressure, hemoglobin, and trauma score were not predictors of major renal trauma. All cases were managed nonoperatively except for 1 patient who required a partial nephrectomy for continued hemorrhage. These data suggest that hematuria of any degree should be evaluated in the pediatric population, since major injuries can occur with even microscopic hematuria or in the absence of shock. Nonoperative management in this series resulted in no morbidity or delayed complications and suggests that surgical exploration be reserved for ongoing bleeding.

The cloning of a receptor-type protein tyrosine phosphatase expressed in the central nervous system

We have isolated cDNA clones and deduced the complete amino acid sequence of a large receptor-type protein tyrosine phosphatase containing 2307 amino acids. The human gene encoding this phosphatase, denoted RPTP beta (or PTP zeta), has been localized to chromosome 7q31-33. RPTP beta is composed of a large extracellular domain, a single transmembrane domain, and a cytoplasmic portion with two tandem catalytic domains. We have also cloned a variant of RPTP beta lacking 859 amino acids from the extracellular domain but with intact transmembrane and cytoplasmic domains. Interestingly, the amino-terminal region of the extracellular domain of RPTP beta contains a stretch of 266 amino acids with striking homology to the enzyme carbonic anhydrase. Immunoprecipitation experiments from a human neuroblastoma cell line indicate that the apparent molecular mass of the core and glycosylated forms of RPTP beta are approximately 250 and 300 kDa, respectively. Northern blot analysis shows that RPTP beta is strictly expressed in the central nervous system. In situ hybridization was used to further localize the expression to different regions of the adult brain including the Purkinje cell layer of the cerebellum, the dentate gyrus, and the subependymal layer of the anterior horn of the lateral ventricle. Hence, RPTP beta represents the first mammalian tyrosine phosphatase whose expression is restricted to the nervous system. The high level of expression of RPTP beta transcripts in the ventricular and subventricular zones of the embryonic mouse brain suggests the importance of this tyrosine phosphatase in the development of the central nervous system.

Identification of a carbonic anhydrase-like domain in the extracellular region of RPTP gamma defines a new subfamily of receptor tyrosine phosphatases

The tyrosine phosphatase RPTP gamma is a candidate tumor suppressor gene since it is located on human chromosome 3p14.2-p21 in a region frequently deleted in certain types of renal and lung carcinomas. In order to evaluate its oncogenic potential and to explore its normal in vivo functions, we have isolated cDNAs and deduced the complete sequences of both human and murine RPTP gamma. The murine RPTP gamma gene has been localized to chromosome 14 to a region syntenic to the location of the human gene. Northern (RNA) blot analysis reveals the presence of two major transcripts of 5.5 and 8.5 kb in a variety of murine tissues. In situ hybridization analysis reveals that RPTP gamma mRNA is expressed in specific regions of the brain and that the localization of RPTP gamma changes during brain development. RPTP gamma is composed of a putative extracellular domain, a single transmembrane domain, and a cytoplasmic portion with two tandem catalytic tyrosine phosphatase domains. The extracellular domain contains a stretch of 266 amino acids with striking homology to the zinc-containing enzyme carbonic anhydrase (CAH), indicating that RPTP gamma and RPTP beta (HPTP zeta) represent a subfamily of receptor tyrosine phosphatases. We have constructed a model for the CAH-like domain of RPTP gamma based upon the crystal structure of CAH. It appears that 11 of the 19 residues that form the active site of CAH are conserved in RPTP gamma. Yet only one of the three His residues that ligate the zinc atom and are required for catalytic activity is conserved. On the basis of this model we propose that the CAH-like domain of RPTP gamma may have a function other than catalysis of hydration of metabolic CO2.

Osteoclasts express high levels of pp60c-src in association with intracellular membranes

Deletion of the c-src gene in transgenic mice by homologous recombination leads to osteopetrosis, a skeletal defect characterized by markedly deficient bone resorption (Soriano, P., C. Montgomery, R. Geske, and A. Bradley. 1991. Cell. 64:693-702), demonstrating a critical functional role of pp60c-src in osteoclast activity. Since decreased bone resorption could result from a defect either within the osteoclast or within other cells present in its environment, indirectly affecting osteoclast functions, we determined which cell(s) in bone expressed high levels of pp60c-src Measuring pp60c-src protein and kinase activities in osteoclasts and immunolocalizing pp60c-src in bone, we find that expression of pp60c-src is nearly as high in osteoclasts as in brain and platelets. In contrast, other bone cells contain only very low levels of the protein. In addition, expression of the c-src gene product increases when bone marrow cells are induced to express an osteoclast-like phenotype by 1,25-dihydroxy-vitamin D3, further suggesting that high expression of pp60c-src is part of the osteoclast phenotype. Three other src-like kinases, c-fyn, c-yes, and c-lyn, are also expressed in osteoclasts at ratios to pp60c-src similar to what is found in platelets. These src-related proteins do not, however, compensate for the absence of pp60c-src in the src- mice, thereby suggesting that pp60c-src may have a specific function in osteoclasts. Although further work is necessary to elucidate what the critical role of pp60c-src in osteoclasts is, our observation that the protein is associated mostly with the membranes of intracellular organelles suggests the possibility that this role might be at least in part related to the targeting or fusion of membrane vesicles.

Analysis of cDNAs of the proto-oncogene c-src: heterogeneity in 5' exons and possible mechanism for the genesis of the 3' end of v-src

To further characterize the gene structure of the proto-oncogene c-src and the mechanism for the genesis of the v-src sequence in Rous sarcoma virus, we have analyzed genomic and cDNA copies of the chicken c-src gene. From a cDNA library of chicken embryo fibroblasts, we isolated and sequenced several overlapping cDNA clones covering the full length of the 4-kb c-src mRNA. The cDNA sequence contains a 1.84-kb sequence downstream from the 1.6-kb pp60c-src coding region. An open reading frame of 217 amino acids, called sdr (src downstream region), was found 105 nucleotides from the termination codon for pp60c-src. Within the 3' noncoding region, a 39-bp sequence corresponding to the 3' end of the RSV v-src was detected 660 bases downstream of the pp60c-src termination codon. The presence of this sequence in the c-src mRNA exon supports a model involving an RNA intermediate during transduction of the c-src sequence. The 5' region of the c-src cDNA was determined by analyzing several cDNA clones generated by conventional cloning methods and by polymerase chain reaction. Sequences of these chicken embryo fibroblast clones plus two c-src cDNA clones isolated from a brain cDNA library show that there is considerable heterogeneity in sequences upstream from the c-src coding sequence. Within this region, which contains at least 300 nucleotides upstream of the translational initiation site in exon 2, there exist at least two exons in each cDNA which fall into five cDNA classes. Four unique 5' exon sequences, designated exons UE1, UE2, UEX, and UEY, were observed. All of them are spliced to the previously characterized c-src exons 1 and 2 with the exception of type 2 cDNA. In type 2, the exon 1 is spliced to a novel downstream exon, designated exon 1a, which maps in the region of the c-src DNA defined previously as intron 1. Exon UE1 is rich in G+C content and is mapped at 7.8 kb upstream from exon 1. This exon is also present in the two cDNA clones from the brain cDNA library. Exon UE2 is located at 8.5 kb upstream from exon 1. The precise locations of exons UEX and UEY have not been determined, but both are more than 12 kb upstream from exon 1. The existence and exon arrangements of these 5' cDNAs were further confirmed by RNase protection assays and polymerase chain reactions using specific primers. Our findings indicate that the heterogeneity in the 5' sequences of the c-src mRNAs results from differential splicing and perhaps use of distinct initiation sites. All of these RNAs have the potential of coding for pp60c-src, since their 5' exons are all eventually joined to exon 2.

Biological and biochemical properties of the c-src+ gene product overexpressed in chicken embryo fibroblasts

The c-src protein isolated from neuronal cells (pp60c-src+) displays a higher level of protein kinase activity than does pp60c-src from nonneural tissues. There are two structural alterations present in the amino-terminal half of pp60c-src+ expressed in neurons which could contribute to the enhanced activity of this form of pp60c-src: (i) a hexapeptide insert located at amino acid 114 of avian pp60c-src+ and (ii) a novel site(s) of serine phosphorylation. We characterized pp60c-src+ expressed in a nonneuronal cell type to identify factors that regulate the activity of the c-src+ protein and the importance of the neuronal environment on this regulation. The c-src+ protein overexpressed in chicken embryo fibroblasts (CEFs) displayed higher kinase activity than did pp60c-src. The major sites of phosphorylation of the c-src+ protein were Ser-17 and Tyr-527. The unique site(s) of serine phosphorylation originally identified in pp60c-src+ expressed in neurons was not detected in the c-src+ protein overexpressed in CEFs. Therefore, the hexapeptide insert is sufficient to cause an elevation in the tyrosine protein kinase activity of pp60c-src+. Our data also indicate that CEFs infected with the Rous sarcoma virus (RSV)c-src+ display phenotypic changes that distinguish them from cultures producing pp60c-src and that pp60c-src+-expressing cells are better able to grow in an anchorage-independent manner. The level of total cellular tyrosine phosphorylation in RSVc-src+-infected cultures was moderately higher than the level observed in cultures infected with RSVc-src. This level was not as pronounced as that observed in cells infected with RSVv-src or oncogenic variants of RSVc-src. Thus, pp60c-src+ could be considered a partially activated c-src variant protein much like other c-src proteins that contain mutations in the amino-terminal domain.

The structurally distinct form of pp60c-src detected in neuronal cells is encoded by a unique c-src mRNA

A cellular src (c-src) cDNA clone was isolated from a chicken embryonic brain cDNA library and characterized by DNA sequence analysis. Comparison with the published sequence of a chicken genomic c-src clone indicated that the brain cDNA clone contained an 18-base-pair insertion located between exons 3 and 4 of the c-src gene. The six amino acids encoded by the insertion caused an alteration in the electrophoretic mobility of the c-src gene product similar to that of the structurally distinct form of the src protein detected in neuronal cultures.

Amino acid substitutions sufficient to convert the nontransforming p60c-src protein to a transforming protein

We have previously shown that Rous sarcoma virus variants that carry the cellular homolog (c-src) of the viral src gene (v-src) do not transform chicken embryo fibroblasts. We also have shown that replacement of sequences upstream or downstream from the BglI site of the cellular src gene with the corresponding regions of v-src restored transforming activity to the hybrid genes. Since there are only six amino acid changes between p60c-src and p60v-src within the sequences upstream from BglI, we constructed chimeric molecules involving v-src and c-src to determine the effect of each amino acid substitution on the biological activities of the gene product. We found that the change from Thr to Ile at position 338 or the replacement of a fragment of c-src containing Gly-63, Arg-95, and Thr-96 with a corresponding fragment of v-src containing Asp-63, Trp-95, and Ile-96 converted p60c-src into a transforming protein by the criteria of focus formation, anchorage-independent growth, and tumor formation in newborn chickens. These mutations also resulted in elevation of the protein kinase activity of p60c-src.

The timing of compaction: control of a major developmental transition in mouse early embryogenesis

The effect of protein synthesis inhibitors on compaction of the 8-cell mouse embryo has been investigated. The effects observed depended upon the duration and time of drug application and on the features of compaction scored. Continuous application from the late 2-cell or early 4-cell stages allowed cell flattening and surface polarization to occur in most embryos and advanced development of these features in many of them. Cell coupling developed only when drug addition was delayed until the mid 4-cell stage, and cytoplasmic polarization developed only when drug addition was delayed until the late 4-cell stage. We suggest that control over the timing of compaction is achieved at a post-translational level via a global permissive change within the blastomeres of the embryo.

Activation of the transforming potential of p60c-src by a single amino acid change

Previous work showed that overexpression of the cellular src (c-src) gene does not cause transformation of chicken cells in culture. However, viral stocks isolated from cells transfected with Rous sarcoma virus DNA containing the c-src gene in place of the viral src gene did occasionally produce foci. Virus obtained from these foci were highly transforming and appeared to arise via spontaneous mutation in the c-src-containing viral populations. The p60 proteins of the transforming mutant src viruses were found to have higher levels of in vitro tyrosine kinase activity than the levels observed with the parental viruses. In this study, we have molecularly cloned the src DNA sequences of two transforming mutant src viruses. When compared to the DNA sequence of the parental c-src viruses, the mutant viruses contain single point mutations that result in single amino acid changes in the src gene products (p60 proteins). Both amino acid changes reside in the tyrosine kinase domain of the protein. The mutation detected in one virus involves replacement of the normal Glu-378 in p60c-src by Gly, whereas the p60 of the other transforming virus has Phe instead of the normal Ile-441. Our data indicate that when p60c-src is expressed at elevated levels in a retroviral context, a single amino acid change in its primary sequence can activate the kinase activity of this protein and cause cellular transformation.

Isolation of chicken cellular DNA sequences with homology to the region of viral oncogenes that encodes the tyrosine kinase domain

A library of chicken genomic DNA was screened for sequences that could hybridize to a cloned DNA fragment containing the transforming gene (v-fps) of Fujinami sarcoma virus. In addition to c-fps, two unique chicken cellular DNA sequences were isolated that hybridized weakly to v-fps. These sequences hybridized with many other viral oncogenes encoding tyrosine kinases. Sequence analysis of the region where homology was detected revealed a region that is highly conserved among the tyrosine kinases both at the nucleotide and amino acid levels. Although we were unable to detect expression of either chicken cellular DNA sequence in a variety of avian tissues, the data suggest the existence of additional members of the tyrosine kinase gene family. Screening genomic libraries for sequences that hybridize weakly to functional regions of other genes may prove useful for the isolation and characterization of additional members of other gene families.

Gene structure and nucleotide sequence for rat cytochrome P-450c

Two clones from rat genomic libraries that contain the entire gene for rat cytochrome P-450c have been isolated. lambda MC4, the first clone isolated from an EcoR1 library, contained a 14-kb insert. A single 5.5-kb EcoR1 fragment from lambda MC4, the EcoR1 A fragment, hybridized to a partial cDNA clone for the 3' end of the cytochrome P-450c mRNA. This fragment was sequenced using the dideoxynucleotide chain termination methodology with recombinant M13 bacteriophage templates. Comparison of this sequence with the complete cDNA sequence of cytochrome P-450MC [Yabusaki et al. (1984) Nucleic. Acids Res. 12, 2929-2938] revealed that the EcoR1 A fragment contained the entire cytochrome P-450c gene with the exception of a 90-bp leader sequence. The gene sequence is in perfect agreement with the cDNA sequence except for two bases in exon 2. A second genomic clone, lambda MC10, which was isolated from a HaeIII library, contains the missing leading sequence as well as 5' regulatory sequences. The entire gene is about 6.1 kb in length with seven exons separated by six introns, all of the intron/exon junctions being defined by GT/AG. Amino- and carboxy-terminal information are contained in exons 2 and 7, respectively. These exons contain the highly conserved DNA sequences that have been observed in other cytochrome P-450 species. Potential regulatory sequences have been located both 5' to the gene as well as within intron I. A comparison of the coding information for cytochrome P-450c with the sequence of murine cytochrome P3-450 and rat cytochrome P-450d revealed a 70% homology in both the DNA and amino acid sequence, suggesting a common ancestral gene. Genomic blot analyses of rat DNA indicated that the 3-methylcholanthrene-inducible family of cytochrome P-450 isozymes is more limited in number compared to the phenobarbital-inducible isozymes. Cross-hybridization studies with human DNA suggest a high degree of conservation between rat cytochrome P-450c and its human homolog although gross structural differences do exist between the two genes.

Molecular induction by phenobarbital of a rat hepatic form of cytochrome P-450: expression of a 4-kilobase messenger RNA

A differential screening procedure was employed to isolate a cDNA clone corresponding to a major phenobarbital (PB)-inducible form of rat hepatic cytochrome P-450. The G-C homopolymer-tailing technique was utilized to construct a cDNA library in the PstI site of plasmid pBR322. The library represented PB-induced poly(A+)RNA sequences from hepatic polysomes of 150-g male Sprague-Dawley rats. Hybrid-selection experiments against total PB-inducible RNA were performed with plasmid DNA derived from clones enriched in PB-inducible information. The mRNA molecules that specifically hybridized were subjected to in vitro translation, were immunoprecipitated with antibody raised in rabbits against purified cytochrome P-450b (P. E. Thomas, D. Korzeniowski, D. Ryan, and W. Levin (1979) Arch. Biochem. Biophys. 192, 524-532), and were electrophoresed under sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoretic conditions. One cDNA clone, designated PB-8, contained a 600-bp insert partially coding for a PB-inducible cytochrome P-450 species that comigrated on SDS-gel electrophoresis with highly purified P-450b. A single injection of PB, 15-18 h before sacrifice, increased the level of polysomal poly(A+)RNA complementary to the isolated cDNA clone by approximately 16-fold. Northern blot hybridizations of polysome-derived poly (A+)RNA, electrophoresed in denaturing agarose gels, demonstrated that the size of the mRNA corresponding to the isolated clone was 4 kb. Isolated heteronuclear RNA species demonstrated a time-dependent increase in the synthesis of a similar 4-kb RNA molecule. By genomic blot hybridization to EcoRI-restricted DNA, at least three complementary DNA fragments migrating at 5.1, 3.2, and 2.9 kb were observed with 32P-labeled PB-8 as a probe. These data, together with restriction endonuclease mapping and partial cDNA sequence information of the PB-8 cDNA, suggest that the PB-8 clone represents a previously unreported cDNA clone for a form of cytochrome P-450 inducible by PB.