Gaucher disease: in vivo evidence for allele dose leading to neuronopathic and nonneuronopathic phenotypes

Gaucher disease, a common lysosomal storage disorder, is associated with mutations at the acid beta-glucosidase (GCase) locus. Two affected individuals are described to share a common mutant allele, but manifest different clinical categorical phenotypes. A 57-year-old female, with Gaucher disease type 1 and Cherokee ancestry, was homozygous for a rare mutant allele encoding Lys79Asn (K79N). A 2-year-old Caucasian male, with Gaucher disease type 3 and Cherokee ancestry, was a heteroallelic homozygote for this same allele (K79N) and a novel complex mutation (null allele). The shared alleles were identical as determined by complete gene sequencing, suggesting a founder effect. The discrepant phenotypes (types 1 and 3) in these two patients provide support for a threshold of residual activity necessary to "protect" the central nervous system (CNS) from the pathogenic effects of Gaucher disease, indicating an allele dose-effect. Designation of genotype associations with specific phenotypes must be assessed with this perspective.     

Disposition of the manchette in the normal equine spermatid

Bielanski and Kaczmarski (1979) reported the presence of microtubules in the neck region of mature stallion spermatozoa. It was hypothesized that these microtubules are derived from the manchette (a microtubular organelle present during spermiogenesis). In order to test this hypothesis, testes from 15 mature stallions were collected, perfused with 2% phosphatebuffered glutaraldehyde, and prepared for transmission electron microscopy. Spermatozoa from the caudae epididymides of each stallion were prepared in a similar manner. Spermiogenesis was observed in general, and the presence of a microtubular manchette was established in this species, juxtapositioned posterior to the nuclear ring and extending distally into the cytoplasmic collar which surrounds the prospective midpiece. Interlocking arms between the microtubules of the manchette were observed in transverse sections at all levels within the cytoplasmic collar before, during, and after caudal migration of the nuclear ring. Consequent to caudal migration of the nuclear ring and the annulus, as well as adluminal movement of the spermatid, the cytoplasmic collar was transformed into the residual cytoplasm. Within the residual cytoplasm, the manchette remained as a microtubular organelle which undergoes degeneration. The mature spermatozoa from the caudae epididymides of these stallions lacked the microtubules reported by Bielanski and Kaczmarski. The occurrence of such microtubules in the neck region of stallion spermatozoa is probably an abnormality.     

Homeostasis and the age-associated defect of CD4 T cells

Survival and homeostatic division of naive CD4 T cells is regulated by the cellular and non-cellular milieu and together these processes ensure that a population of naive CD4 T cells persists into old age. However, the naive CD4 T cells from aged animals show reduced IL-2 production, proliferation, helper function and effector generation and memory function. We explore here whether the age-related defects in naive CD4 T cells are due to the aged environment from which they come or to intrinsic defects that are caused by homeostasis and their long lifespan.     

Which treatment for whom for ADHD? Moderators of treatment response in the MTA

Using receiver operating characteristics, the authors examined outcome predictors (variables associated with outcome regardless of treatment) and moderators (variables identifying subgroups with differential treatment effectiveness) in the Multimodal Treatment Study of Children with Attention-Deficit/Hyperactivity Disorder (ADHD; MTA). Treatment response was determined using parent- and teacher-reported ADHD and oppositional defiant symptoms, with levels near or within the normal range indicating excellent response. Among 9 baseline child and family characteristics, none predicted but 3 moderated treatment response. In medication management and combined treatments, parental depressive symptoms and severity of child ADHD were associated with decreased rates of excellent response; when these 2 characteristics were present, below-average child IQ was an additional moderator. No predictors or moderators emerged for behavioral and community comparison treatments. The authors discuss conceptual and clinical implications of research on treatment moderators.     

Hepatic DNA adduct dosimetry in rats fed tamoxifen: a comparison of methods

Liver homogenates from rats fed tamoxifen (TAM) in the diet were shared among four different laboratories. TAM-DNA adducts were assayed by high pressure liquid chromatography-electrospray tandem mass spectrometry (HPLC-ES-MS/MS), TAM-DNA chemiluminescence immunoassay (TAM-DNA CIA), and (32)P-postlabeling with either thin layer ((32)P-P-TLC) or liquid chromatography ((32)P-P-HPLC) separation. In the first study, rats were fed a diet containing 500 p.p.m. TAM for 2 months, and the values for measurements of the (E)-alpha-(deoxyguanosin-N(2)-yl)-tamoxifen (dG-N(2)-TAM) adduct in replicate rat livers varied by 3.5-fold when quantified using 'in house' TAM-DNA standards, or other approaches where appropriate. In the second study, rats were fed 0, 50, 250 or 500 p.p.m. TAM for 2 months, and TAM-DNA values were quantified using both 'in house' approaches as well as a newly synthesized [N-methyl-(3)H]TAM-DNA standard that was shared among all the participating groups. In the second study, the total TAM-DNA adduct values varied by 2-fold, while values for the dG-N(2)-TAM varied by 2.5-fold. Ratios of dG-N(2)-TAM:(E)-alpha-(deoxyguanosin-N(2)-yl)-N-desmethyltamoxifen (dG-N(2)-N-desmethyl-TAM) in the second study were approximately 1:1 over the range of doses examined. The study demonstrated a remarkably good agreement for TAM-DNA adduct measurements among the diverse methods employed.     

Two novel paradigms for the simultaneous assessment of conditioned taste aversion and food intake effects of anorexic agents

The conditioned taste aversion (CTA) is routinely used to assess the aversive consequences of anorexic agents, including potential pharmacological therapies for obesity. In a typical CTA paradigm, rats briefly sampling a novel tastant (e.g., saccharin) are acutely administered with toxin (e.g., lithium chloride, LiCl). After as few as one taste-toxin pairing, rats will reliably avoid the novel tastant. This paradigm is frequently used for the assessment of possible aversive consequences of drugs that are candidates for pharmacological therapies. The degree to which the drug supports development of a CTA is interpreted as an index of its aversive properties. Difficulties with previous work include the inability to assess affects on food intake and CTA simultaneously, particularly during chronic drug administration. We report here two novel CTA paradigms for the assessment of appetitive and aversive consequences of anorexic agents, simultaneously. In the first experiment, animals receive an intraoral infusion of a novel and highly palatable tastant immediately prior to administration of increasing doses of LiCl. In the second experiment, rats were implanted intraperitoneally with osmotic minipumps that chronically delivered a low dose of LiCl for 7 days. LiCl did not affect short or long term food intake in either experiment. However, LiCl did support the development of a CTA in both paradigms. These results suggest that both the appetitive and aversive consequences of anorexic agents can be assessed simultaneously during either acute or chronic drug administration.