Juvenile rats in the forced-swim test model the human response to antidepressant treatment for pediatric depression

RATIONALE

Currently, there are limited treatment options for major depressive disorder in children and adolescents compared to the options available for adults. Many effective treatments used for adult depression, such as the tricyclic antidepressants, lack efficacy when given to children and adolescents.

OBJECTIVE

To more quickly identify compounds that could be effective for treating childhood and adolescent depression, a reliable preclinical animal behavioral test of antidepressant efficacy for pediatric depression is needed. The forced-swim test (FST) with juvenile rats was assessed to determine its reliability as a predictive model for pediatric depression.

MATERIALS AND METHODS

We adapted procedures from the adult FST to test 21-day-old juvenile rats. The 21-day-old animals were treated with three classes of antidepressant drugs before being assessed in the FST: the selective serotonin reuptake inhibitors escitalopram or fluoxetine; the tricyclic antidepressants desipramine or imipramine; and the monoamine oxidase inhibitor tranylcypromine.

RESULTS

The 21-day-old rats showed dose-dependent changes in behaviors similar to those seen in adults when treated with escitalopram or fluoxetine. Tranylcypromine also decreased immobility in 21-day-old rats. Treatment with desipramine or imipramine, however, was not effective at reducing immobility in the 21-day-old rats.

CONCLUSIONS

The juvenile FST accurately predicts the efficacy of selective serotonin reuptake inhibitors and the lack of efficacy of tricyclic antidepressants in the treatment of depression in children and adolescents. This suggests that the FST using 21-day-old rats may help to develop better treatments for childhood and adolescent depression.

Childhood and adolescent depression: why do children and adults respond differently to antidepressant drugs?

Childhood and adolescent depression is an increasingly problematic diagnosis for young people due to a lack of effective treatments for this age group. The symptoms of adult depression can be treated effectively with multiple classes of antidepressant drugs which have been developed over the years using animal and human studies. But many of the antidepressants used to treat adult depression cannot be used for pediatric depression because of a lack of efficacy and/or side effects. The reason that children and adolescents respond differently to antidepressant treatment than adults is poorly understood. In order to better understand the etiology of pediatric depression and treatments that are effective for this age group, the differences between adults, children and adolescents needed to be elucidated. Much of the understanding of adult depression has come from studies using adult animals, therefore studies using juvenile animals would likely help us to better understand childhood and adolescent depression. Recent studies have shown both neurochemical and behavioral differences between adult and juvenile animals after antidepressant treatment. Juvenile animals have differences compared to adult animals in the maturation of the serotonergic and noradrenergic systems, and in dose of antidepressant drug needed to achieve similar brain levels. Differences after administration of antidepressant drug have also been reported for adrenergic receptor regulation, a physiologic hypothermic response, as well as behavioral differences in two animal models of depression. The differences between adults and juveniles not only in the human response to antidepressants but also with animals studies warrant a specific distinction between the study of pediatric and adult depression and the manner in which new treatments are pursued.

Differential Effects of the Tricyclic Antidepressant Desipramine on the Density of Adrenergic Receptors in Juvenile and Adult Rats

Although the tricyclic antidepressants, such as desipramine (DMI), are among the most efficacious treatments for adult depression, they are not effective in treating childhood and adolescent depression. Because the adrenergic nervous system is not fully developed until late adolescence, we hypothesized that the mechanisms regulating receptor density may not yet be mature in young mammals. To test this hypothesis, the effects of DMI treatment on cortical alpha-1-, alpha-2-, and beta-adrenergic receptors were compared in juvenile and adult rats. DMI was delivered either by 4 days of twice daily injections to postnatal day 9 to 13 (4 and 7 mg/kg/day) and adult (20 mg/kg/day) rats, or by 2 weeks of continual drug infusion (osmotic minipumps) to postnatal day 21-35 (15 mg/kg/day) and adult (10 mg/kg/day) rats. These delivery paradigms gave juvenile brain concentrations of DMI similar to those in adult rats. The beta-adrenergic receptor was down-regulated with both treatment paradigms in both juvenile and adult rats. By contrast, in the postnatal day 9 to 13 rats, there was a dose-dependent up-regulation of the alpha-1 in the cortex and alpha-2-adrenergic receptor in the prefrontal cortex, whereas there was no change in density in adult rats. These differences in the alpha-adrenergic receptor regulation after DMI treatment suggest that the lack of efficacy of tricyclic antidepressants in treating childhood depression may be related to immature regulatory mechanisms for these receptors.

Detection of head and neck squamous cell carcinoma among exfoliated oral mucosal cells by microsatellite analysis

Prompt detection of head and neck squamous cell carcinoma (HNSCC) is vital to successful patient management. In this feasibility study, we used microsatellite analysis to detect tumor-specific genetic alterations in exfoliated oral mucosal cell samples from patients with known cancer. Exfoliated mucosal cells in pretreatment oral rinse and swab samples were collected from 44 HNSCC patients and from 43 healthy control subjects (20 nonsmokers and 23 smokers). We tested a panel of 23 informative microsatellite markers to assay DNA from the matched lymphocyte, tumor (from cancer cases), and oral test samples. Loss of heterozygosity or microsatellite instability of at least one marker was detected in 38 (86%) of 44 primary tumors. Identical alterations were found in the saliva samples in 35 of these 38 cases (92% of those with markers; 79% overall) including 12 of 13 cases with small primaries [stage Tt or Tx (occult primary)] and 4 of 4 cases of patients that had undergone prior radiation. Microsatellite instability was detectable in the saliva in 24 (96%) of 25 cases in which it was present in the tumor, and loss of heterozygosity was identified in the test sample in 19 (61%) of 31 cases. No microsatellite alterations were detected in any of the samples from the healthy control subjects. This approach must now be refined and validated for the detection of clinically occult disease. Microsatellite analysis of oral samples may then become a valuable method for detecting and monitoring HNSCC.

Multicentric lymphosarcoma in a dog with multiple-site skeletal involvement

In this report the authors describe an unusual clinical presentation of lymphosarcoma (LSA) in a dog. A 9-year-old, neutered male, Golden Retriever was presented with a primary complaint of sudden onset of tetraparesis. Routine survey radiographs revealed multiple-site bony lesions and the histology revealed a diagnosis of LSA with diffuse skeletal and soft tissue involvement. The dog responded poorly to medical management and was euthanized on day two due to poor prognosis. Malignant LSA of the bone is a rare extranodal clinicopathologic entity and presents both a diagnostic and therapeutic hurdle. Reports of this kind are sparse and currently no optimal treatment for this entity has been determined.

Impaired CD4 T cell activation due to reliance upon B cell-mediated costimulation in nonobese diabetic (NOD) mice

Diabetes in nonobese diabetic (NOD) mice results from the activation of I-A(g7)-restricted, islet-reactive T cells. This study delineates several characteristics of NOD CD4 T cell activation, which, independent of I-A(g7), are likely to promote a dysregulated state of peripheral T cell tolerance. NOD CD4 T cell activation was found to be resistant to antigenic stimulation via the TCR complex, using the progression of cell division as a measure. The extent of NOD CD4 T cell division was highly sensitive to changes in Ag ligand density. Moreover, even upon maximal TCR complex-mediated stimulation, NOD CD4 T cell division prematurely terminated. Maximally stimulated NOD CD4 T cells failed to achieve the threshold number of division cycles required for optimal susceptibility to activation-induced death, a critical mechanism for the regulation of peripheral T cell tolerance. Importantly, these aberrant activation characteristics were not T cell-intrinsic but resulted from reliance on B cell costimulatory function in NOD mice. Costimulation delivered by nonautoimmune strain APCs normalized NOD CD4 T cell division and the extent of activation-induced death. Thus, by disrupting the progression of CD4 T cell division, polarization of APC costimulatory function to the B cell compartment could allow the persistence and activation of diabetogenic cells in NOD mice.

Two distinct regions of loss on chromosome arm 4q in primary head and neck squamous cell carcinoma

OBJECTIVE

To more clearly define the frequency and the regions of chromosome arm 4q loss in head and neck squamous cell carcinoma.

DESIGN

A retrospective microsatellite analysis of DNA from previously microdissected primary tumor samples.

SETTING

Academic medical center.

PATIENTS AND METHODS

One hundred primary tumor samples from patients with head and neck squamous cell carcinoma were analyzed for loss of heterozygosity on the long arm of chromosome 4. The Kaplan-Meier method was used to estimate survival for 97 patients for whom clinical data were available. The Cox proportional hazards model was used to compare survival, and logistic regression was used to search for associations between clinical tumor characteristics and 4q status.

RESULTS

Analysis of 33 polymorphic microsatellite markers identified 51 samples (51%) exhibiting loss of heterozygosity of 4q in at least 1 locus. Eighteen tumors revealed loss at all informative markers, indicating monosomy or complete deletion of 4q. Thirty-three tumors displayed partial loss of heterozygosity and delineated 2 minimal areas of loss at 4q2324 and 4q2829. Eleven tumors displayed loss solely at the 4q2324 region, 13 tumors displayed deletions confined to the 4q2829 region, and 9 tumors displayed selective loss at both regions. A separate analysis in a subset of 94 primary head and neck tumors was done to further delineate the minimal area of chromosomal loss at 4q2324. Analysis of 8 markers in this region allowed us to identify the smallest region of loss between markers D4S2986 and D4S1564 (a distance of 2 centimorgans). Review of the clinical records of 97 patients revealed no statistically significant association between 4q status and any clinical variable, including survival.

CONCLUSION

These results confirm a high frequency of chromosome arm 4q loss in primary head and neck squamous cell carcinoma and might demarcate 2 novel putative suppressor loci involved in progression of this carcinoma.

Effect of dam and sire qualitative hip conformation scores on progeny hip conformation

OBJECTIVE

To determine in dogs what effect using hip conformation scores assigned by the Orthopedic Foundation for Animals (OFA) as a criterion for breeding selections would have on hip conformation scores of the progeny.

DESIGN

Longitudinal study.

ANIMALS

English Setters, Portuguese Water Dogs, Chinese Shar-peis, and Bernese Mountain Dogs for which OFA hip conformation scores were known.

PROCEDURE

Pedigree data were obtained from the national breed clubs and the American Kennel Club and merged with data from the OFA hip conformation score database. An ANOVA was used to evaluate the effects of sex, age at the time of radiographic evaluation, and year of birth on the variation in hip conformation scores among the progeny. Heritability was estimated by use of within-year midparent offspring regression analyses.

RESULTS

Significant differences in progeny hip conformation scores between sexes were not detected, but age at the time of radiographic evaluation and year of birth had a significant effect on hip joint conformation of the progeny. Estimated heritability (mean +/- SE) was 0.26 +/- 0.03, and dam and sire hip conformation scores had a significant effect on progeny hip conformation scores. Annual decreases in percentage of dysplastic progeny and increases in percentages of progeny and breeding dogs with phenotypically normal hip joint conformation were detected.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that hip conformation scores have moderate heritability in dogs and selection of breeding stock with better hip conformation scores will increase the percentage of progeny with phenotypically normal hip joint conformation.

Inactivation of the INK4A/ARF locus frequently coexists with TP53 mutations in non-small cell lung cancer

Inactivation of the P16 (INK4A)/retinoblastoma (RB) or TP53 biochemical pathway is frequent event in most human cancers. Recent evidence has shown that P14ARF binds to MDM2 leading to an increased availability of wild type TP53 protein. Functional studies also support a putative tumor suppressor gene function for p14ARF suggesting that p14ARF or p53 inactivation may be functionally equivalent in tumorigenesis. To study the relative contribution of each pathway in tumorigenesis, we analysed and compared alterations of the p16, p14ARF and p53 genes in 38 primary non-small cell lung cancers (NSCLCs) (19 adenocarcinomas and 19 squamous carcinoma). The p16 tumor suppressor gene was inactivated in 22 of 38 (58%) tumors. Twelve of these samples (31%) had homozygous deletions by microsatellite analysis; eight of them (21%) had p16 promoter hypermethylation detected by Methylation Specific PCR (MSP) and the remaining two (5%) harbored a point mutation in exon 2 by sequence analysis. The absence of P16 protein in every case was confirmed by immunohistochemistry. Fourteen of the 22 tumors with p16 inactivation also inactivated the p14ARF gene (12 with homozygous deletions extending into INK4a/ARF and two with exon 2 mutations). Mutations of p53 were found in 18 (47%) of the tumors and nine of them (50%) harbored p14ARF inactivation. Thus, an inverse correlation was not found between p14ARF and p53 genetic alterations (P=0.18; Fisher Exact Test). Our data confirm that the p16 gene is frequently inactivated in NSCLC. Assuming that 9p deletion occurs first, the common occurrence of p53 and p14ARF alterations suggests that p14ARF inactivation is not functionally equivalent to abrogation of the TP53 pathway by p53 mutation.

Fluoroscopically guided closed reduction and internal fixation of fractures of the lateral portion of the humeral condyle: prospective clinical study of the technique and results in ten dogs

OBJECTIVE

To report a technique for fluoroscopically guided closed reduction with internal fixation of fractures of the lateral portion of the humeral condyle (FLHC) and determine the long-term results in 10 clinical cases.

STUDY DESIGN

Prospective clinical case study.

ANIMALS

Ten dogs with 11 fractures.

METHODS

Fractures of the lateral portion of the humeral condyle were stabilized with transcondylar screws and Kirschner wires. Closed reduction and implant placement were achieved using intraoperative fluoroscopic guidance. After fracture repair, postoperative radiographs were evaluated for articular alignment and implant placement. Dogs were evaluated after surgery by means of lameness scores, elbow range of motion (ROM), radiographic assessment, and owner evaluation of function.

RESULTS

Postoperative reduction was considered anatomic in 6 fractures with all other fractures having <1.5 mm of malreduction. Follow-up was available for 9 patients from 9 to 21 months after surgery. All of the fractures had healed. One minor (wire migration) and one major (implant failure) complication occurred. Mean lameness scores were 0 (n = 6), 0.5 (n = 2), and 1 (n = 1) at the time of final follow-up. No significant differences were found in follow-up ROM values between affected and unaffected elbows. All of the dogs in this study regained 90-100% of full function, based on owner assessment.

CONCLUSIONS AND CLINICAL RELEVANCE

Fluoroscopic guidance for closed reduction and internal fixation of FLHC in dogs is an effective technique.

Hip dysplasia: a feline population study

The study population consisted of cats presented to the University of Missouri-Columbia Veterinary Medical Teaching Hospital from January 1, 1991 through December 31, 1995. Ventrodorsal radiographs including the pelvic region were evaluated for radiographic evidence of hip dysplasia. Each radiograph was evaluated independently by three board-certified veterinary radiologists and a consensus normal of dysplastic evaluation was determined. There were 684 cats from 12 breeds. The data derived from this study indicate the frequency of feline hip dysplasia in this population to be about 6.6% (45/684) and that the incidence appears to be breed dependent. Also, the radiographic appearance of hip dysplasia in cats is different than in dogs. A shallow acetabulum with remodeling and proliferation involving the cranio-dorsal acetabular margin were the most common radiographic signs. Minimal remodeling of the femoral neck was seen.

Cyclin D1 amplification is independent of p16 inactivation in head and neck squamous cell carcinoma

Progression through the G1 phase of the cell cycle is mediated by phosphorylation of the retinoblastoma protein (pRb) resulting in the release of essential transcription factors such as E2F-1. The phosphorylation of pRb is regulated positively by cyclin D1/CDK4 and negatively by CDK inhibitors, such as p16 (CDKN2/MTS-1/INK4A). The p16/cyclin D1/Rb pathway plays a critical role in tumorigenesis and many tumor types display a high frequency of inactivation of at least one component of this pathway. In order to determine the overall contribution of these three components to progression of head and neck squamous cell carcinoma (HNSCC), we examined p16 inactivation, cyclin D1 amplification, and pRb expression in 23 primary HNSCC tumors and five cell lines. p16 inactivation was detected in 19/23 (83%) primary tumors by detailed genetic analysis and was confirmed by immunohistochemistry (IHC). Absence of Rb protein expression indicative of pRb inactivation was identified in 2/23 (9%) tumors. In this set of tumors, there was a perfect inverse correlation between p16 and pRb inactivation. Using fluorescence in situ hybridization (FISH) cyclin D1 amplification was identified in 4/5 (80%) cell lines and 4/11 (36%) primary tumors. However, 2/4 cell lines and all four primary tumors with cyclin D1 amplification contained a concomitant alteration of p16. Therefore 21/ 23 (91%) of primary HNSCC contained at least one alteration in the p16/cyclin D1/Rb pathway. Although p16 and Rb alteration are apparently exclusive, cyclin D1 amplification occurs concomitantly with the loss of p16 suggesting an additional role for this amplification in HNSCC.

Molecular cloning and characterization of a transcription regulator with homology to GC-binding factor

GC-binding factor (GCF) represses transcription of certain genes and is encoded by a 3.0-kilobase mRNA (Kageyama, R., and Pastan, I. (1989) Cell 59, 815-825). The GCF cDNA hybridizes to two additional mRNA species, 4.2 and 1.2 kilobases. We have used differential hybridization to identify a cDNA clone (termed GCF2) for the 4. 2-kilobase mRNA and find that it is highly expressed in HUT-102 cells. The open reading frame consists of 2256 nucleotides and encodes a protein of 752 amino acids with a calculated molecular mass of 83 kilodaltons. GCF2 expressed in vitro using reticulocyte lysates and Escherichia coli migrates as a 160-kilodalton protein in SDS-polyacrylamide gel electrophoresis but has a molecular mass of 83 kilodaltons as determined by mass spectrum analysis. GCF2 binds to epidermal growth factor receptor promoter fragments, and the major binding site is located between nucleotides -249 and -233. Cotransfection assays show that GCF2 acts to repress transcription from the epidermal growth factor receptor promoter in constructs containing the major GCF2 binding site and not when the site had been mutated. Thus, GCF2 is a newly identified transcriptional repressor with aberrant electrophoretic mobility.

Analysis of PTEN/MMAC1 alterations in aerodigestive tract tumors

PTEN/MMAC1 is a candidate tumor suppressor gene recently identified at chromosomal band 10q23. It is mutated in sporadic brain, breast, and prostate cancer and in the germ line of patients with hereditary Cowden disease. We searched for genetic alterations of the PTEN/MMAC1 gene in 39 primary head and neck cancers (HNSCCs), 42 primary non-small cell lung cancers (NSCLCs), 80 pancreatic cancer xenografts, and 37 cell lines and xenografts from colon, lung, and gastric cancers. Microsatellite analysis revealed loss of heterozygosity at markers near the gene in 41% of primary HNSCCs, 50% of NSCLCs, and 39% of the pancreatic cancers. Three cases of HNSCCs displayed homozygous deletion involving the gene. We sequenced the entire coding region of the PTEN/MMAC1 gene in the remaining tumors displaying loss of heterozygosity and found one terminating mutation in a HNSCC sample. Thus, a second inactivation event was observed in 4 of 39 primary HNSCC cases. By use of a protein truncation assay, one terminating mutation was also identified in one of eight NSCLC cell lines. Our results suggest that PTEN/MMAC1 gene inactivation plays a role in the genesis of some tumor types.

Normal polymorphism in the incomplete trinucleotide repeat of the arginine-rich protein gene

The arginine-rich protein (ARP) gene was recently cloned and localized to human chromosome band 3p21. Recent reports have suggested that ARP is mutated in a high percentage of different human tumors. We amplified and sequenced the multiple arginine coding area of the ARP gene in primary head and neck, non-small cell lung, and renal cell cancers. We found a high frequency of genetic changes in this region, including a single base pair substitution and deletions of arginine repeats in primary tumors. However, these changes were always present in matched normal controls. Thus, the variations in the ARP trinucleotide repeat region represent normal polymorphisms rather than tumor-specific mutations.

High frequency of p16 (CDKN2/MTS-1/INK4A) inactivation in head and neck squamous cell carcinoma

The tumor suppressor gene p16 (CDKN2/MTS-1/INK4A) can be inactivated by multiple genetic mechanisms. We analyzed 29 invasive primary head and neck squamous cell carcinomas (HNSCC) for p16 inactivation with immunohistochemistry utilizing a new monoclonal antibody (mAb), DCS-50. p16 staining of the primary lesions was correlated with genetic analysis including: (a) detailed microsatellite analysis of markers at the p16 locus to detect homozygous deletion; (b) sequence analysis of p16; and (c) Southern blot analysis to determine the methylation status of the 5' CpG island of p16. Twenty-four of 29 (83%) head and neck squamous cell carcinoma tumors displayed an absence of p16 nuclear staining using immunohistochemistry. Of these 24 tumors, we found that 16 (67%) harbored homozygous deletions, 5 (21%) were methylated, 1 displayed a rearrangement at the p16 locus, and 1 displayed a frameshift mutation in exon 1. These data suggest that: (a) inactivation of the p16 tumor suppressor gene is a frequent event in squamous cell carcinomas of the head and neck; (b) p16 is inactivated by several distinct and exclusive events including homozygous deletion, point mutation, and promoter methylation; and (c) immunohistochemical analysis for expression of the p16 gene product is an accurate and relatively simple method for evaluating p16 gene inactivation.

Effects of electric field exposure on some indices of CNS arousal in the mouse

Mice given ELF electric field exposures of 50-400 Vm-1 at frequencies of 15, 30, and 50 Hz failed to display any significant changes in barbiturate sleeping time or exploratory activity.