Administration of an AAV vector coding for a P2X7-blocking nanobody-based biologic ameliorates colitis in mice

BACKGROUND

The pro-inflammatory ATP-gated P2X7 receptor is widely expressed by immune and non-immune cells. Nanobodies targeting P2X7, with potentiating or antagonistic effects, have been developed. Adeno-associated virus (AAV)-mediated gene transfer represents an efficient approach to achieve long-term in vivo expression of selected nanobody-based biologics. This approach (AAVnano) was used to validate the relevance of P2X7 as a target in dextran sodium sulfate (DSS)-induced colitis in mice.

RESULTS

Mice received an intramuscular injection of AAV vectors coding for potentiating (14D5-dimHLE) or antagonistic (13A7-Fc) nanobody-based biologics targeting P2X7. Long-term modulation of P2X7 activity was evaluated ex vivo from blood samples. Colitis was induced with DSS in mice injected with AAV vectors coding for nanobody-based biologics. Severity of colitis, colon histopathology and expression of chemokines and cytokines were determined to evaluate the impact of P2X7 modulation. A single injection of an AAV vector coding for 13A7-Fc or 14D5-dimHLE efficiently modulated P2X7 function in vivo from day 15 up to day 120 post-injection in a dose-dependent manner. An AAV vector coding for 13A7-Fc significantly ameliorated DSS-induced colitis and significantly reduced immune cell infiltration and expression of chemokines and proinflammatory cytokines in colonic tissue.

CONCLUSIONS

We have demonstrated the validity of AAVnano methodology to modulate P2X7 functions in vivo. Applying this methodological approach to a DSS-induced colitis model, we have shown that P2X7 blockade reduces inflammation and disease severity. Hence, this study confirms the importance of P2X7 as a pharmacological target and suggests the use of nanobody-based biologics as potential therapeutics in inflammatory bowel disease.

Targeting multiple myeloma with nanobody-based heavy chain antibodies, bispecific killer cell engagers, chimeric antigen receptors, and nanobody-displaying AAV vectors

Nanobodies are well suited for constructing biologics due to their high solubility. We generated nanobodies directed against CD38, a tumor marker that is overexpressed by multiple myeloma and other hematological malignancies. We then used these CD38-specific nanobodies to construct heavy chain antibodies, bispecific killer cell engagers (BiKEs), chimeric antigen receptor (CAR)-NK cells, and nanobody-displaying AAV vectors. Here we review the utility of these nanobody-based constructs to specifically and effectively target CD38-expressing myeloma cells. The promising results of our preclinical studies warrant further clinical studies to evaluate the potential of these CD38-specific nanobody-based constructs for treatment of multiple myeloma.

Evaluation of nanobody-based biologics targeting purinergic checkpoints in tumor models in vivo

Adenosine triphosphate (ATP) represents a danger signal that accumulates in injured tissues, in inflammatory sites, and in the tumor microenvironment. ATP promotes tumor growth but also anti-tumor immune responses notably via the P2X7 receptor. ATP can also be catabolized by CD39 and CD73 ecto-enzymes into immunosuppressive adenosine. P2X7, CD39 and CD73 have attracted much interest in cancer as targets offering the potential to unleash anti-tumor immune responses. These membrane proteins represent novel purinergic checkpoints that can be targeted by small drugs or biologics. Here, we investigated nanobody-based biologics targeting mainly P2X7, but also CD73, alone or in combination therapies. Blocking P2X7 inhibited tumor growth and improved survival of mice in cancer models that express P2X7. P2X7-potentiation by a nanobody-based biologic was not effective alone to control tumor growth but enhanced tumor control and immune responses when used in combination with oxaliplatin chemotherapy. We also evaluated a bi-specific nanobody-based biologic that targets PD-L1 and CD73. This novel nanobody-based biologic exerted a potent anti-tumor effect, promoting tumor rejection and improving survival of mice in two tumor models. Hence, this study highlights the importance of purinergic checkpoints in tumor control and open new avenues for nanobody-based biologics that may be further exploited in the treatment of cancer.

Enhanced Transduction of P2X7-Expressing Cells with Recombinant rAAV Vectors

Adeno-associated viruses (AAV) are useful vectors for transducing cells in vitro and in vivo. Targeting of specific cell subsets with AAV is limited by the broad tropism of AAV serotypes. Nanobodies are single immunoglobulin variable domains from heavy chain antibodies that naturally occur in camelids. Their small size and high solubility allow easy reformatting into fusion proteins. In this chapter we provide protocols for inserting a P2X7-specific nanobody into a surface loop of the VP1 capsid protein of AAV2. Such nanobody-displaying recombinant AAV allow 50- to 500-fold stronger transduction of P2X7-expressing cells than the parental AAV. We provide protocols for monitoring the transduction of P2X7-expressing cells by nanobody-displaying rAAV by flow cytometry and fluorescence microscopy.

Point mutation in codons 12 and 61 of the Ha-ras gene in rat urinary bladder carcinomas induced by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide

Male F344 rats were fed N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) for up to 4 wk, then were given the basal diets (Prolab 3200 or AIN-76A) with or without 5% sodium saccharin for up to 100 wk. Eleven transitional cell carcinomas (TCCs), one undifferentiated carcinoma, and two sarcomas of the urinary bladder were examined for the expression of ras gene product, p21, by immunohistochemical staining and western blot analysis. Point mutation in codons 12 or 61 of the Ha-ras genes amplified by polymerase chain reaction was examined by a slot-blot screening procedure using allele-specific oligonucleotide probes. Immunohistochemical staining showed enhanced immunoreactivity with the antibody to ras p21 in seven TCCs and one undifferentiated carcinoma. Western blot analysis showed faster migration of the p21 band in 6 of 11 TCCs. Oligonucleotide hybridization revealed the point mutation in codon 12 of Ha-ras gene (GGA----GTA in 1 TCC) and in codon 61 (CAA----CGA in 5 TCCs and CAA----CTA in 1 TCC). Two mutations in codons 12 and 61 coexisted in one tumor, which were found to be present in different Ha-ras alleles. The incidence of Ha-ras gene mutations were similar in groups treated with (3 of 6) or without (3 of 8) sodium saccharin. These results suggest the involvement of activated Ha-ras gene in rat urinary bladder carcinogenesis induced by FANFT.

Normalisation of gait data in children

The comparative effect of semi-dimensional (SD) and non-dimensional (ND) normalisation on the results of a longitudinal study of gait in 5-12-year old children was investigated. The use of both height and leg length in the normalisation was examined. Only ND analysis could be used to identify subjects with the same accelerations. ND analysis of the children's gait indicated that there was little change in the combination of step length and cadence used to achieve a particular velocity between 5 and 12. The first peak and mid-stance trough values of the vertical component of ground reaction force did not change with age. We recommend the use of ND normalisation rather that SD to allow comparisons between individuals of differing size and mass.

Sagittal joint kinematics, moments, and powers are predominantly characterized by speed of progression, not age, in normal children

Twenty-six healthy 7-year-old children were enrolled in a 5-year longitudinal study to examine the importance of age and speed in the characterization of sagittal joint angles, moments, and powers. In 740 gait trials, children walking at self-selected speeds were examined on the basis of age and normalized speed [speed/(height x g)1/2]. The kinematics and kinetics in these children were characterized predominantly by normalized speed of progression and not age. The clinical relevance of these findings is that normalized speed of walking, rather than age, should be considered when comparing normal with pathologic gait.

Normalized speed, not age, characterizes ground reaction force patterns in 5-to 12-year-old children walking at self-selected speeds

Twenty-six healthy 5-year-old children were enrolled in a 7-year longitudinal study to examine the importance of age and speed in the characterization of ground reaction forces. One thousand forty gait trials of children walking at self-selected speeds were examined on the basis of age and normalized speed [speed/(height x g)(1/2)]. Results, presented as discrete peak and trough values and as continuous trace plots over the stance phase, indicated that there was little change in ground reaction forces with age, but there were significant changes in vertical force and anterior-posterior force values with normalized speed. The ground reaction force patterns in these children were characterized predominantly by normalized speed of progression and not age. The clinical relevance of these findings is that normalized speed of walking, rather than age, should be considered when comparing normal with pathological gait.

Immunization entry at the point of service improves quality, saves time, and is well-accepted

OBJECTIVE

Computer-based immunization tracking is a routine part of many pediatric practices; however, data quality is inconsistent and entry often relies on dedicated data entry personnel and is time-consuming, expensive, or difficult. The purpose of this study was to evaluate data quality, nursing satisfaction, and reduction in documentation burden after the introduction of a point-of-service immunization entry system in an inner-city pediatric primary care center.

DESIGN

Prospective preintervention and postintervention study.

METHODS

Visit records from all pediatric nonurgent care visits for patients <5 years old were collected during a 2-week period before (preintervention) and after (postintervention) the introduction of a computer-based immunization entry system. Nurses used software designed to allow rapid entry during immunization preparation followed by printing 2 adhesive labels for documentation. Satisfaction was evaluated using an 8-question survey administered 3 months after the intervention.

RESULTS

One hundred forty-seven (63.6%) of 231 preintervention and 132 (51.4%) of 257 postintervention children received at least 1 immunization (immunized) during the study visit. Gender and mean age were similar for immunized children in the 2 groups. In the preintervention group, 56 (37.9%) of 147 immunized children had at least 1 dose missing (a total of 128 of 343 doses administered) from the immunization tracking database compared with none in the postintervention group. Medical record review showed that 92.6% of preintervention and 91.4% of postintervention children were on-schedule after the study visit. However, missing data lead to the misclassification of preintervention children-only 68.4% were reported by the database to be on-schedule. All 9 nurses reported using the program all the time to enter immunizations, 89% said that the program required somewhat or a lot less time, and 100% strongly recommended continued use of the program. All 9 nurses also reported that they would be somewhat or very unenthusiastic about the system if labels were not available. During the 12 months after introduction of the system, 8273 forms containing immunization information were printed, preventing nurses from having to write >101,000 dates.

CONCLUSIONS

Immunization entry by nurses at the time of immunization preparation improves the quality of tracking data, reduces misclassification of immunization needs, saves time, and can be well-accepted. It is likely that poor data quality in some tracking systems has led to falsely low immunization coverage estimates. Systems such as the one in this study can improve quality and should be integrated into routine clinical practice.

neu is not involved in N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide-induced bladder carcinoma or 2-amino-4-(5-nitro-2-furyl)thiazole transformation of rat bladder epithelial cells

Enhanced c-erbB-2/neu expression has been linked with a poor prognosis in human bladder cancer. Previous reports have shown that a point mutation at nucleotide T2012 in the coding region of the transmembrane domain of the rat gene is sufficient to confer transformation potential on this gene. We examined the comparative levels of p185neu as well as the sequence around the hotspot (T2012) of the neu gene of rat bladder cells transformed by 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT) or established in culture from N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT)-induced rat bladder tumors. We concluded that increased p185neu expression did not correlate significantly with tumorigenicity. No alterations in nucleotide sequences of the neu gene were observed in either in vitro model.

Neu is not involved in N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide- induced bladder carcinoma or 2-amino-4-(5-nitro-2-furyl)thiazole transformation of rat bladder epithelial cells

Enhanced c-erbB-2/neu expression has been linked with a poor prognosis in human bladder cancer. Previous reports have shown that a point mutation at nucleotide T2012 in the coding region of the transmembrane domain of the rat gene is sufficient to confer transformation potential on this gene. We examined the comparative levels of p185neu as well as the sequence around the hotspot (T2012) of the neu gene of rat bladder cells transformed by 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT) or established in culture from N-[-4-(-5-nitro-2-furyl)-2- thiazolyl]formamide (FANFT)-induced rat bladder tumors. We concluded that increased p185neu expression did not correlate significantly with tumorigenicity. No alterations in nucleotide sequences of the neu gene were observed in either in vitro model.

Mutations and expression of the p53 gene in rat bladder carcinomas and cell lines

Abnormalities of the p53 gene are frequently observed in human tumors, including urinary bladder carcinoma, suggesting that p53 plays an important role in human carcinogenesis. However, its role in rat bladder carcinogenesis is unclear. We investigated p53 gene mutations and expression in rat urinary bladder carcinogenesis in vivo and in vitro. Fifteen urothelial cell lines, including six untransformed (nontumorigenic) ones, six transformed (tumorigenic) in vitro, and three derived from tumors induced in vivo, were examined for p53 expression by immunochemical analysis and for p53 mutations; in addition, 81 rat bladders were analyzed immunohistochemically for p53 expression, and 23 rat bladder tumors were analyzed for p53 mutations. Four cell lines had mutations in the p53 gene. Two of these were missense point mutations, and the other two were splicing mutations. On the other hand, no mutations were found in the bladder tumors induced in rats. By immunoprecipitation with PAb240, which is supposed to be specific for mutant p53, we detected mutations in three of the cell lines; PAb240 did not react with wild-type p53. However, in all cell lines and in growing populations of primary cultured bladder urothelial cells, p53 expression was detected immunohistochemically or by western blotting using PAb240 or PAb 421 monoclonal antibodies. In a high percentage of transitional cell carcinomas, wild-type p53 expression was detected by immunohistochemical analysis with PAb240. These results suggest that p53 gene mutations may not occur frequently in rat bladder carcinogenesis in vivo but may occur in vitro and that p53 overexpression detected immunohistochemically is common and may be related to cell proliferation rather than to the presence of mutations in rat bladder carcinogenesis.

p53 mutation is infrequent and might not give a growth advantage in rat bladder carcinogenesis in vivo

Abnormalities of the p53 gene are frequently observed in human tumors, including urinary bladder carcinoma, suggesting that p53 plays an important role in human carcinogenesis. However, its role in rat bladder carcinogenesis is unclear. In this study, we investigated the presence of p53 mutations in 122 urinary bladder tumors induced in F344 rats in the following carcinogenesis models: (i) 0.2% N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT; 6 weeks) in the diet followed by 3% or 5% sodium saccharin in the diet, 5% sodium ascorbate, 3.12% calcium saccharin (CaSac), 1.34% sodium chloride (NaCl), 5.2% CaSac plus 1.34% NaCl, or basal diet alone (72 weeks); and (ii) 0.2% FANFT, 0.05% N-(4-hydroxybutyl)nitrosamine in the drinking water, N-methyl-N-nitrosourea 20 mg/kg body wt, i.p. twice per week, or basal diet alone (4 weeks), followed by 3% uracil in the diet (20 weeks). Polymerase chain reaction-single-strand conformation polymorphism analysis and direct sequencing were performed for exons 5-8 in the rat p53 gene. We found nine tumors (7.4%) with p53 mutations. Two tumors had two mutations in the p53 gene. The tumors that had p53 mutations were relatively smaller than those that did not have p53 mutations. There were no mutation clusters among the treatments or hot-spots for p53 mutations. These results indicate that p53 mutation is infrequent in bladder carcinogenesis in rats, and when it does occur, it does not appear to provide a growth advantage.

Sequencing analysis of Ha-, Ki-, and N-ras genes in rat urinary bladder tumors induced by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) and sodium saccharin

Male F344 rats were fed N[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) for up to 4 wk, then given the basal diet with or without 5% sodium saccharin for up to 100 wk. In a previous study, we demonstrated point mutations in codons 12 and 61 of Ha-ras gene among eleven transitional cell carcinomas (TCC), one undifferentiated carcinoma, and two sarcomas of the urinary bladder (Mol Carcinogen 3:210-215, 1990). In this study, Ha-ras, Ki-ras, and N-ras sequences were examined by polymerase chain reaction (PCR) and direct DNA sequencing. The results confirm the point mutation in codon 61 (CAA to CGA in 5 TCCs and to CTA in one TCC) of the Ha-ras gene. Mutation at codon 12 was not confirmed. No mutation was found in the Ki-ras gene. Sequences of the N-ras gene exons 1 and 2 were determined, and no mutations was detected. These results suggest the involvement of activated Ha-ras gene, but not Ki-N or N-ras gene, in rat urinary bladder carcinogenesis induced by FANFT. Subsequent sodium saccharin administration did not affect the changes in Ha-ras gene.

Absence of ras oncogene activation in rat urinary bladder carcinomas induced by N-methyl-N-nitrosourea or N-butyl-N-(4-hydroxybutyl)nitrosamine

Previously, we demonstrated point mutations of the H-ras gene in N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT)-induced rat urinary bladder carcinomas. In this study, ras oncogene activation was examined in urinary bladder carcinomas induced by N-(4-hydroxybutyl)nitrosamine (BBN) or N-methyl-N-nitrosourea (MNU) administration followed by uracil treatment. In the first experiment, MNU (20 mg/kg body wt) was i.p. injected into 11 male F344 rats twice a week for 4 weeks, followed by feeding 3% uracil for 20 weeks (MNU/uracil group). Ten rats were given only 3% uracil without MNU pretreatment. In the second experiment, 20 male F344 rats were given 0.05% BBN in the drinking water for 4 weeks, then fed 3% uracil for 20 weeks (BBN/uracil group). Another 20 rats were fed 3% uracil without the BBN pretreatment. Transitional cell carcinomas were induced in the urinary bladder of all rats in the MNU/uracil and BBN/uracil groups. Papillomas and hyperplasias were present in the rats given uracil without prior BBN or MNU. DNA and protein were extracted from the tumors (MNU/uracil or BBN/uracil groups) or from the scraped bladder epithelium (uracil alone groups). Sequences around codons 12, 13 and 61 of H-, K- and N-ras genes were examined by direct sequencing after polymerase chain reaction, and p21 was examined by Western blotting. No mutation was found within the examined sequences and p21 showed no changes in mobility. There was no difference in the level of p21 expression between rats treated with MNU/uracil or BBN/uracil compared to corresponding uracil alone groups. These results indicate that the ras oncogene was not activated in urinary bladder carcinomas induced by BBN or MNU in combination with uracil treatment, in contrast to previous findings with FANFT.

Ras involvement in cells transformed with 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT) in vitro and with N-[4-(5-nitro-2-furyl)-2-thiazoyl]formamide in vivo

N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) administration to rats followed by sodium saccharin results in transitional cell carcinomas of the bladder, of which 24% harbor an activated H-ras gene. Since 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT) is the mutagenic and carcinogenic metabolite of FANFT in vivo, we wished to examine ras activation in in vitro ANFT-transformed rat bladder epithelial cells as well as four cell lines established in culture from in vivo FANFT-induced rat bladder tumors. Screening by Western blotting revealed no enhanced levels of p21ras in ANFT-transformed cells nor in cells established in culture from FANFT-induced rat bladder carcinomas. Further investigations using immunohistochemical staining with a different pan-reactive p21 monoclonal antibody (Cetus Corporation) specific for this method, however, showed two groups of cells from FANFT-induced rat bladder tumors had enhanced immunoreactivity. Apart from this, p21ras expression of most of the cells groups varied little from the controls. We examined the reported hot spots (exons 1 and 2) of each of the ras genes (H-, K- and N-ras) by direct sequencing of amplified DNA. No mutations were present. We conclude, therefore, that ANFT transformation of primary rat bladder epithelial cells in vitro may not in this case be mediated by ras activation, although this is difficult to determine since others have observed that optimal culture conditions can select for certain populations of cells without ras activation.

Direct DNA sequencing of the rat neu oncogene transmembrane domain reveals no mutation in urinary bladder carcinomas induced by N-butyl-N-(4-hydroxybutyl)nitrosamine, N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide or N-methyl-N-nitrosourea

Epidermal growth factor (EGF) and EGF-related growth factors are present in the urine, and EGF has been identified as a urinary component that enhances urinary bladder tumor formation in rats. Neu oncogene encodes a cell surface receptor similar to the EGF receptor and is known to be activated by a point mutation of DNA that encodes the transmembrane domain of the neu protein (p185). In this study, we examined the possible mutational activation of neu oncogene in 50 urinary bladder transitional cell carcinomas (TCC) induced in F344 rats by the following carcinogenesis models: (i) 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) (4 weeks)----3% uracil (20 weeks); (ii) 0.2% N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) (6 weeks)----5% sodium saccharin (72 weeks); and (iii) N-methyl-N-nitrosourea (MNU) 20 mg/kg body wt, i.p. twice per week for 4 weeks----3% uracil (20 weeks). The DNA sequence around the transmembrane domain of neu gene was amplified by PCR and sequenced. The results showed no mutation within the examined DNA sequences, indicating that neu oncogene is not activated by a point mutation in the transmembrane domain in urinary bladder carcinomas induced by BBN, FANFT or MNU.

H-ras mutations in rat urinary bladder carcinomas induced by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide and sodium saccharin, sodium ascorbate, or related salts

Male F344 rats were fed 0.2% N-[4-(5-nitro-2-furyl)-2-thiazoly]formamide for 6 weeks and then fed 3% or 5% sodium saccharin, 5% sodium ascorbate, 3.12% calcium saccharin, 1.34% sodium chloride, 5.2% calcium saccharin plus 1.34% sodium chloride, or basal diet alone for 72 weeks. Protein and DNA were extracted from 89 bladder tumors [87 transitional cell carcinomas (TCC), 1 papilloma, and 1 sarcoma] from 86 rats p21 expression was examined by Western blotting using a monoclonal antibody against p21 (NCC-RAS-004). H-ras mutations in exons 1 and 2 were examined by direct sequencing of DNA amplified by polymerase chain reaction. Sequencing results demonstrated mutations at codon 61 (CAA to CGA in 15 TCCs; CAA to CTA in 2 TCCs), at codon 12 (GGA to TGG in 1 TCC), and at codon 13 (GGC to GTC in 3 TCCs). Mutations at codon 61 were confirmed by faster mobility of the p21 band in Western blots. The level of p21 expression varied among samples, but many TCCs appeared to express more p21 than controls. The overall incidence of H-ras mutations was 24.4% (21 of 86 rats). The type of chemical used for the promoting phase had essentially no effect on H-ras mutation, suggesting that the effects observed were related to FANFT administration. The frequency of H-ras mutation in each group was negatively related to the incidence of carcinoma (r = -0.85; P less than 0.01). Two groups of tumors (with or without the mutated ras gene) were compared for tumor size (reflected by the bladder weight), histological grading, and the presence of invasion. The size of tumors with mutated ras was significantly smaller than those without mutated ras. There was no difference in the histological grading between the two groups. Although not statistically significant, histological invasion was more frequently observed in tumors with mutated ras (14.3%) than in tumors without mutation (3.1%).

In vitro transformation of rat bladder epithelium by 2-amino-4-(5-nitro-2-furyl)thiazole

To establish a rat urinary bladder carcinogenesis model in vitro, primary rat bladder epithelial cells were grown in media containing 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT), the water-soluble metabolite of N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide (FANFT), for 4 weeks followed by long-term (4-7 months) exposure to control medium, sodium saccharin (NaS), or urea. Another set of cultures were exposed to ANFT, NaS and urea simultaneously. Several phenotypic changes were observed in the chemically exposed cell cultures, namely differences in cell morphology, increased growth rate and the ability to grow on plastic instead of rat-tail collagen support. All of the chemically exposed cultures were anchorage independent except one of those treated with NaS. The ANFT-treated cells followed by control medium or urea and cells treated with ANFT, NaS and urea were tumorigenic when transplanted to nude mice, whereas NaS or ANFT followed by NaS treatment were not. The tumors were carcinomas and their epithelial differentiation was verified by strong positive staining for cytokeratin. These studies demonstrate the urothelial transforming capability of ANFT in cell culture without the necessity for a long exposure to a secondary chemical.

Cloning and characterization of human immunodeficiency virus type 1 variants diminished in the ability to induce syncytium-independent cytolysis

The phenomenon of interference was exploited to isolate low-abundance noncytopathic human immunodeficiency virus type 1 (HIV-1) variants from a primary HIV-1 isolate from an asymptomatic HIV-1-seropositive hemophiliac. Successive rounds of virus infection of a cytolysis-susceptible CD4+ cell line and isolation of surviving cells resulted in selective amplification of an HIV-1 variant reduced in the ability to induce cytolysis. The presence of a PvuII polymorphism facilitated subsequent amplification and cloning of cytopathic and noncytopathic HIV-1 variants from the primary isolate. Cloned virus stocks from cytopathic and noncytopathic variants exhibited similar replication kinetics, infectivity, and syncytium induction in susceptible host cells. The noncytopathic HIV-1 variant was unable, however, to induce single-cell killing in susceptible host cells. Construction of viral hybrids in which regions of cytopathic and noncytopathic variants were exchanged indicated that determinants for the noncytopathic phenotype map to the envelope glycoprotein. Sequence analysis of the envelope coding regions indicated the absence of two highly conserved N-linked glycosylation sites in the noncytopathic HIV-1 variant, which accompanied differences in processing of precursor gp160 envelope glycoprotein. These results demonstrate that determinants for syncytium-independent single-cell killing are located within the envelope glycoprotein and suggest that single-cell killing is profoundly influenced by alterations in envelope sequence which affect posttranslational processing of HIV-1 envelope glycoprotein within the infected cell.

Strong promoting activity by uracil on urinary bladder carcinogenesis and a possible inhibitory effect on thyroid tumorigenesis in rats initiated with N-methyl-N-nitrosourea

Uracil has been shown to cause a strong proliferative response in the urinary bladder epithelium of rats and mice through calculus formation and, consequently, acts as a strong promoter in bladder carcinogenesis. In this study, we examined the effect of uracil on two-stage carcinogenesis in various organs using N-methyl-N-nitrosourea (MNU) as the initiator. F344 rats were injected i.p. with MNU twice weekly for 4 weeks and then given diet containing 3.0% uracil for 20 weeks. Uracil induced urinary bladder carcinomas in all rats pretreated with MNU, and it decreased the combined incidence of adenomas and carcinomas in the thyroid. Although not significant, uracil decreased the incidence of adenomas in the lung and increased that of lymphomas of the thymus. A possible influence of a significantly decreased body weight gain caused by uracil treatment on the reduced tumor incidence in the thyroid and lung is discussed. The present data demonstrate the strong promotion activity of uracil for urinary bladder carcinogenesis, and suggest a possible inhibitory effect on thyroid carcinogenesis.

Envelope glycoprotein of HIV induces interference and cytolysis resistance in CD4+ cells: mechanism for persistence in AIDS

Masking of host cell receptors following retroviral infection is the basis for the phenomenon of virus interference. Amphotropic retrovirus vectors were used to express the HIV envelope glycoprotein in a human CD4+ cell line. Envelope expression is accompanied by a reduction in the level of surface CD4 receptor molecules and correlates with the presence of intracellular envelope-CD4 receptor complexes. Cells expressing the HIV envelope acquire a cytolysis-resistant phenotype such that infection with HIV leads to a non-cytopathic persistent virus infection. Furthermore, phorbol ester-mediated stimulation of viral replication in persistently infected cells results in renewed cytolytic effects which, due to the absence of CD4 in the cell population, are absolutely independent of syncytium formation. This study elucidates the mechanism by which viral persistence is initiated and maintained in the course of AIDS.

Effects of 1,2-dibromoethane on glutathione metabolism in rat liver and kidney

There are few reports of the effects of glutathione-depleting agents administered for periods longer than 24 hr on the turnover of glutathione (GSH) in mammalian tissues. Studies of such effects are important in relation to the protection of tissues from damage from, for example, reactive metabolites derived from xenobiotics. In the investigation described here, 1,2-dibromoethane dibromide)-a widely used insecticide, nematocide, fungicide and petrol additive, which is hepato- and nephrotoxic-was administered to rats and the effects on non-protein thiol contents and GSH-related enzyme activities were determined in liver and kidney. The classical GSH-depleter diethylmaleate was used in parallel studies for comparative purposes.

Further experience in conjoint psychotherapy of marital pairs

Conjoint therapy of marital partners is a technique that lends itself to the counseling efforts of health professionals. Its growing use has, however, brought with it seemingly inevitable pitfalls, such as inadequate assessment of individual needs and psychopathology, overzealous application and disregard of certain contraindications, management problems and goal definition that may be unclear to patients or more related to the therapist's personality than to an objective view of the marriage dynamics. Despite the difficulties and pitfalls of this relatively new field, conjoint therapy can be the treatment of choice when the primary difficulties are related to the inability to cope in the marital situation, even though functioning in other social roles is adequate.

Psychological sequelae of accidental injury: a medico-legal quagmire

LITIGATION FOR PERSONAL INJURY FOLLOWING ACCIDENTAL TRAUMA IS AN EXPENSIVE AND CONFUSED PROCESS INVOLVING THREE PROTAGONISTS: patient, doctor and lawyer. Although post-traumatic conditions can be elaborately classified, the intrinsic validity of such classifications is often questionable. Current methods of evaluating psychological sequelae of accidental injury are inaccurate and unsatisfactory, partly because of the protagonists' conceptual, motivational and semantic differences. In addition, there is no really satisfactory method of (a) determining and quantifying minor but significant degrees of brain damage, (b) distinguishing these from "post-traumatic neurosis", or (c) determining the relationship between the trauma and subsequent disturbance of function. Increasingly "expert" advice is solicited but owing to the nature of the data and conditions of examination, such advice does little to clarify the underlying problems. Furthermore, doctors are often unable to communicate effectively to the judiciary just how the trauma has affected the patient. Even though certain suggestions for improvement are advanced, the need for comprehensive, longitudinal research is inescapable.

Conjoint psychotherapy of marital pairs

Many traditional concepts are being challenged in contemporary psychiatric practice, including the classical "one-to-one" relationship of individual psychotherapy. Where the patient's presenting difficulties include significant inability to function or feel happy in the marital role, the technique of conjoint psychotherapy (having both partners treated simultaneously by the same doctor) may be indicated. Conjoint therapy is envisaged as a continuum, embracing a considerable range of situations where it is sound practice to see husband and wife together. The treatment plan has three stages: complaint, clarification, and compromise, each of which presents specific features and pitfalls. Emphasis is placed on dealing with individual psychopathology of each partner, both per se and in relation to the marital situation. Results to date suggest that conjoint treatment represents a promising therapeutic modality. Even in cases where individual psychopathology cannot fully be resolved, certain plateaus of satisfaction may be attained as communication improves.

Diagnosis and treatment of delirium

Delirium is not a clinical entity but a symptom-complex of manifold etiology. Its presence signifies acute cerebral insufficiency and often represents a medical and/or psychiatric emergency.Though some forms of delirium have distinctive features, the fundamental phenomena are common to all, with clouding of consciousness the sine qua non. The condition has two major components: (1) the basic "acute brain syndrome" and (2) associated release phenomena.Clinicians must first make the vital differentiation between delirium and "functional" mental disorder, then proceed with the elucidation of the underlying diagnosis and the concurrent organization of symptomatic and etiologic treatment.Proper treatment combines management of the acute brain syndrome with general and specific procedures for control of the underlying condition. Dealing with the symptom-complex itself involves the principles and practice of sedation, hydration, and nutrition, nursing care and supportive measures. Provided the basic organic condition is treatable, the prognosis today is usually good.

The Desmethyl Metabolite of Imipramine (G-35020) in the Treatment of Depression: Further Clinical Experience

The desmethyl metabolite of imipramine (DMI) was used to treat 103 depressed patients, standard dosage being 50 mg. thrice daily orally. Seventy patients recovered or were much improved. The indication for DMI and its activity spectrum were of the same order as imipramine. Side effects were less frequent and less severe. Average onset of definitive improvement was three days; earliest changes noted were in facies, motility, and relief of guilt feelings. Besides the classical straightforward response, seven patients improved early but relapsed, and 12 showed a "plateau effect". Absence of favourable response after seven days necessitated reevaluation and/or substitution of other approaches. DMI may be the drug of choice in initiating treatment of depression, but seemed insufficient alone to deal with agitated, acutely suicidal patients. Although DMI appeared an effective, fast-acting antidepressant, there is still no panacea for this ubiquitous syndrome, whose proper management calls for flexibility and awareness of its multifactorial etiology.