Comparing Flaxseed and Perindopril in the Prevention of Doxorubicin and Trastuzumab-Induced Cardiotoxicity in C57Bl/6 Mice

Background: Two anti-cancer agents, doxorubicin (DOX) and trastuzumab (TRZ), are commonly used in the management of breast cancer in women. Despite their efficacy in reducing the morbidity and mortality of individuals with breast cancer, the use of these agents is limited by adverse cardiotoxic side effects. Both the nutraceutical agent flaxseed (FLX) and the pharmaceutical drug perindopril (PER) have been studied individually in the prevention of chemotherapy-mediated cardiac dysfunction. The objective of this study was to determine whether the prophylactic administration of FLX is comparable and/or synergistic with PER in preventing DOX + TRZ-induced cardiotoxicity. Methods: Over a six-week period, 81 wild-type C57Bl/6 female mice (8–12 weeks old) were randomized to receive regular chow (RC) or 10% FLX-supplemented diets with or without PER (3 mg/kg/week; oral gavage). Starting at week 4, mice were randomized to receive a weekly injection of saline or DOX (8 mg/kg) + TRZ (3 mg/kg). Serial echocardiography was conducted weekly and histological and biochemical analyses were performed at the end of the study. Results: In mice treated with RC + DOX + TRZ, left ventricular ejection (LVEF) decreased from 75 ± 2% at baseline to 37 ± 3% at week 6. However, prophylactic treatment with either FLX, PER, or FLX + PER partially preserved left ventricular systolic function with LVEF values of 61 ± 2%, 62 ± 2%, and 64 ± 2%, respectively. The administration of FLX, PER, or FLX + PER was also partially cardioprotective in preserving cardiomyocyte integrity and attenuating the expression of the inflammatory biomarker NF-κB due to DOX + TRZ administration. Conclusion: FLX was equivalent to PER at preventing DOX + TRZ-induced cardiotoxicity in a chronic in vivo murine model.

Earlier radiosurgery leads to better pain relief and less medication usage for trigeminal neuralgia patients: an international multicenter study

OBJECTIVE

Trigeminal neuralgia (TN) is a chronic pain condition that is difficult to control with conservative management. Furthermore, disabling medication-related side effects are common. This study examined how stereotactic radiosurgery (SRS) affects pain outcomes and medication dependence based on the latency period between diagnosis and radiosurgery.

METHODS

The authors conducted a retrospective analysis of patients with type I TN at 12 Gamma Knife treatment centers. SRS was the primary surgical intervention in all patients. Patient demographics, disease characteristics, treatment plans, medication histories, and outcomes were reviewed.

RESULTS

Overall, 404 patients were included. The mean patient age at SRS was 70 years, and 60% of the population was female. The most common indication for SRS was pain refractory to medications (81%). The median maximum radiation dose was 80 Gy (range 50-95 Gy), and the mean follow-up duration was 32 months. The mean number of medications between baseline (pre-SRS) and the last follow-up decreased from 1.98 to 0.90 (p < 0.0001), respectively, and this significant reduction was observed across all medication categories. Patients who received SRS within 4 years of their initial diagnosis achieved significantly faster pain relief than those who underwent treatment after 4 years (median 21 vs 30 days, p = 0.041). The 90-day pain relief rate for those who received SRS ≤ 4 years after their diagnosis was 83.8% compared with 73.7% in patients who received SRS > 4 years after their diagnosis. The maximum radiation dose was the strongest predictor of a durable pain response (OR 1.091, p = 0.003). Early intervention (OR 1.785, p = 0.007) and higher maximum radiation dose (OR 1.150, p < 0.0001) were also significant predictors of being pain free (a Barrow Neurological Institute pain intensity score of I-IIIA) at the last follow-up visit. New sensory symptoms of any kind were seen in 98 patients (24.3%) after SRS. Higher maximum radiation dose trended toward predicting new sensory deficits but was nonsignificant (p = 0.075).

CONCLUSIONS

TN patients managed with SRS within 4 years of diagnosis experienced a shorter interval to pain relief with low risk. SRS also yielded significant decreases in adjunct medication utilization. Radiosurgery should be considered earlier in the course of treatment for TN.

Formation of drug nanocrystals under nanoconfinement afforded by liposomes

In response to freeze–thaw, liposome-encapsulated antibiotic (A) is converted into nanocrystalline form (B) resulting in an attenuated drug release profile.

Correction: Formation of drug nanocrystals under nanoconfinement afforded by liposomes

Correction for ‘Formation of drug nanocrystals under nanoconfinement afforded by liposomes’ by D. Cipolla et al., RSC Adv., 2016, 6, 6223–6233.

A tool to assess clinical signs and symptoms of localized infection in chronic wounds: development and reliability

This paper reports on the development and testing of a tool designed to assess chronic wounds for the clinical signs and symptoms of localized infection. Thirty-one wounds were assessed by two independent nurse observers for the signs and symptoms of infection using the Clinical Signs and Symptoms Checklist. The Clinical Signs and Symptoms Checklist delineates 12 signs and symptoms of infection (i.e., pain, erythema, edema, heat, purulent exudate, serous exudate with concurrent inflammation, delayed healing, discoloration of granulation tissue, friable granulation tissue, pocketing at the base of the wound, foul odor, and wound breakdown) and their definitions. The reliability of each sign or symptom on the checklist was calculated using percent agreement and the Kappa statistic. Percent agreement ranged from 65% to 100%, and Kappa statistics ranged from 0.53 to 1.00, excluding pocketing of the wound base. The reliability estimates obtained for signs and symptoms on the Clinical Signs and Symptoms Checklist compare favorably with other data regarding interclinician agreement on wound assessment. Incorporating a structured approach to assess and monitor for wound infection, such as the Clinical Signs and Symptoms Checklist, may improve clinician skill and accuracy in identifying this condition.

Complex interaction between HLA DR and DQ in conferring risk for childhood type 1 diabetes

Type 1 (insulin-dependent) diabetes mellitus is associated with HLA DR and DQ factors, but the primary risk alleles are difficult to identify because recombination events are rare in the DQ-DR region. The risk of HLA genotypes for type 1 diabetes was therefore studied in more than 420 incident new onset, population-based type 1 diabetes children and 340 age, sex and geographically matched controls from Sweden. A stepwise approach was used to analyse risk by relative and absolute risks, stratification analysis and the predispositional allele test. The strongest relative and absolute risks were observed for DQB1*02-DQA1*0501/DQB1*0302-DQA1*0301 heterozygotes (AR 1/46, P < 0.001) or the simultaneous presence of both DRB1*03 and DQB1*0302 (AR 1/52, P < 0.001). Stratification analysis showed that DQB1*0302 was more frequent among DRB1*04 patients than DRB1*04 controls (P < 0.001), while DRB1*03 was more frequent among both DQA1*0501 (P < 0.001) and DQB1*02 (P < 0.001) patients than respective controls. The predispositional allele test indicated that DRB1*03 (P < 0.001) would be the predominant risk factor on the DRB1*03-DQA1*0501-DQB1*02 haplotype. In contrast, although DQB1*0302 (P < 0.001) would be the predominant risk factor on the DRB1*04-DQA1*0301-DQB1*0302 haplotype, the predispositional allele test also showed that DRB1*0401, but no other DRB1*04 subtype, had an additive risk to that of DQB1*0302 (P < 0.002). It is concluded that the association between type 1 diabetes and HLA is due to a complex interaction between DR and DQ since (1) DRB1*03 was more strongly associated with the disease than DQA1*0501-DQB1*02 and (2) DRB1*0401 had an additive effect to DQB1*0302. The data from this population-based investigation suggest an independent role of DR in the risk of developing type 1 diabetes, perhaps by providing diseases-promoting transcomplementation molecules.

Activity of a ritonavir plus saquinavir-containing regimen in patients with virologic evidence of indinavir or ritonavir failure

OBJECTIVE

To evaluate the virologic activity of a ritonavir plus saquinavir-containing regimen in patients who have failed an indinavir or ritonavir-containing regimen.

DESIGN

Patients were identified through a retrospective study evaluating the incidence of indinavir or ritonavir failure in our clinic.

PATIENTS

Eighteen patients failing indinavir or ritonavir therapy and who switched to a ritonavir-saquinavir-containing regimen were evaluated. Indinavir or ritonavir failure was defined as a plasma viral load > 1500 copies/ml (branched DNA) after 16 weeks of continuous therapy.

INTERVENTIONS

All patients switched to ritonavir (400 mg twice daily) plus saquinavir (400 mg twice daily) and received concurrent therapy with two nucleoside reverse transcriptase inhibitors (NRTI). Twelve of the 18 patients modified their NRTI regimen at the time ritonavir-saquinavir was initiated.

OUTCOME MEASURES

Plasma viral load was monitored using a branched DNA assay. Genotypic analysis was performed using a point mutation differential hybridization technique, and was confirmed with direct sequencing.

RESULTS

Fourteen out of 18 patients completed at least 24 weeks of therapy; the remaining four patients discontinued therapy after week 12 due to a lack of virologic response or intolerance. Plasma viral load decreased a median 1.4 log10 after 4 weeks of treatment with ritonavir-saquinavir. Only four patients had a greater than 0.5 log10 decrease in viral load after 24 weeks of therapy. In eight out of 10 patients evaluated, the V82A mutation was present at the time of the switch to ritonavir-saquinavir. Viral rebound on ritonavir-saquinavir was associated with the emergence of mutations at amino acids 46, 48, 54 and 90.

CONCLUSION

The combination of ritonavir, saquinavir and two NRTI resulted in a moderate but transient suppression of viral replication in patients who have failed indinavir or ritonavir therapy. Failure of ritonavir-saquinavir may be associated with the emergence of mutations associated with resistance to ritonavir/saquinavir monotherapy, particularly the L90M mutation.

Invariant chain-independent function of H-2M in the formation of endogenous peptide-major histocompatibility complex class II complexes in vivo

Efficient loading of major histocompatibility complex class II molecules with peptides requires the invariant chain (Ii) and the class II-like molecule H-2M. Recent in vitro biochemical studies suggest that H2-M may function as a chaperone to rescue empty class II dimers. To test this hypothesis in vivo, we generated mice lacking both Ii and H-2M (Ii-/-M-/-). Antigen presenting cells (APCs) from Ii-/-M-/- mice, as compared with APCs from Ii-/- mice, exhibit a significant reduction in their ability to present self-peptides to a panel of class II I-Ab-restricted T cells. As a consequence of this defect in the loading of self peptides, CD4(+) thymocyte development is profoundly impaired in Ii-/-M-/- mice, resulting in a peripheral CD4(+) T cell population with low levels of T cell receptor expression. These findings are consistent with the idea that H-2M functions as a chaperone in the peptide loading of class II molecules in vivo.

Differential expression of CLIP:MHC class II and conventional endogenous peptide:MHC class II complexes by thymic epithelial cells and peripheral antigen-presenting cells

Major histocompatibility complex (MHC) class II molecules expressed by thymic epithelial cells are involved in positive selection of CD4 T cells, whereas the high-avidity interaction of T cell receptors with the endogenous peptide: MHC class II complexes expressed on bone marrow (BM)-derived antigen-presenting cells (APC) and, to a lesser extent, on thymic epithelial cells mediate negative selection. To understand better the generation of the CD4 T cell repertoire both in the thymus and in the periphery we analyzed relative levels of expression of specific endogenous peptide: MHC class II complexes in thymic epithelial cells (TEC) and peripheral APC. Expression of E alpha52-68: I-A(b) and class II-associated invariant chain peptide (CLIP): I-A(b) complexes in thymic epithelial cells and in the bone-marrow derived splenic APC, i.e. B cells, was studied using YAe and 30-2 monoclonal antibodies which are specific for the corresponding complexes. To distinguish between expression of both complexes in radioresistant thymic epithelial elements and radiation sensitive BM-derived APC, radiation BM chimeras were constructed. Using immunohistochemical and immunochemical approaches we demonstrated that the level of expression of E alpha52-68: I-A(b) complexes in thymic epithelial cells is approximately 5-10% of that seen in splenic cells whereas total class II levels were comparable. In contrast, CLIP: I-A(b) complexes are expressed at substantially higher levels in TEC vs. splenic APC. This result demonstrates quantitative differences in expression of distinct peptide: MHC class II complexes in thymic epithelial cells and peripheral splenic APC.

Nevirapine-resistant human immunodeficiency virus: kinetics of replication and estimated prevalence in untreated patients

The nonnucleoside reverse transcriptase inhibitor nevirapine rapidly selects for mutant human immunodeficiency virus (HIV) in vivo. The most common mutation occurs at amino acid residue 181 in patients receiving monotherapy. After the initiation of nevirapine therapy, plasma and peripheral blood mononuclear cell samples were collected at frequent intervals and assayed for HIV RNA levels and the proportion of virus containing a mutation at residue 181. HIV RNA levels remained stable for the first 24 h after initiation of therapy and rapidly declined between 1 and 7 days. There was a consistent maximum decrease of 2 log10 HIV RNA copies per ml of plasma (range, 1.96 to 2.43) from baseline after 2 weeks in all monotherapy subjects. The estimated median half-life of HIV RNA was 1.11 days (range, 0.63 to 1.61). After 14 days of therapy, HIV RNA levels began to increase and 181 mutant virus was detected. The estimated doubling time of the emerging virus population ranged from 1.80 to 5.73 days. Viral DNA in peripheral blood mononuclear cells turned over from wild type to the mutant with a mutation at residue 181 significantly more slowly than did HIV RNA in plasma. In two subjects, the calculated prevalence of the 181 mutant virus prior to treatment was 7 and 133 per 10,000 copies of plasma HIV RNA.

Variation in HLA-DM expression influences conversion of MHC class II alpha beta:class II-associated invariant chain peptide complexes to mature peptide-bound class II alpha beta dimers in a normal B cell line

The maturation of invariant chain (Ii):MHC class II complexes into peptide-loaded alpha beta dimers occurs by proteolytic removal of Ii chain and binding of antigenic peptides derived from exogenous and endogenous Ags. A fragment of the Ii chain (class II-associated invariant chain peptide (CLIP) remains associated with class II alpha beta and is an intermediate in this process. Conversion of alpha beta:CLIP complexes into alpha beta:peptide complexes is facilitated by HLA-DM. Two unique mAbs, specific for I-Ab bound to human CLIP and I-Ab bound to DR alpha peptide, were used to assess the formation of these peptide:class II complexes in a human B lymphoblastoid cell line (B-LCL) (Swei) transfected with I-A(b). In multiple independent Swei:I-Ab transfectants, the amount of human CLIP (hCLIP):I-Ab expressed was inversely proportional to the amount of DR alpha 52-68:I-Ab; quantitative differences in HLA-DM expression accounted for this phenotype. In the low DM transfectant, a substantial proportion of I-Ab, but not DR molecules, was altered structurally and unable to present native protein Ags. Addition of DM transgenes to the DM-low cells resulted in an increase in DR alpha 52-68:I-Ab coupled with a decrease in hCLIP:I-Ab complexes and restoration of exogenous protein Ag presentation. The DR5 molecules in Swei cells, which have a lower affinity for hCLIP than I-Ab, were not affected by low DM expression, suggesting that the amount of DM required for conversion of CLIP:class II to peptide:class II may depend on the affinity of the class II molecules for CLIP or DM.

Variation in HLA-DM expression influences conversion of MHC class II alpha beta:class II-associated invariant chain peptide complexes to mature peptide-bound class II alpha beta dimers in a normal B cell line

The maturation of invariant chain (Ii):MHC class II complexes into peptide-loaded alpha beta dimers occurs by proteolytic removal of Ii chain and binding of antigenic peptides derived from exogenous and endogenous Ags. A fragment of the Ii chain (class II-associated invariant chain peptide (CLIP) remains associated with class II alpha beta and is an intermediate in this process. Conversion of alpha beta:CLIP complexes into alpha beta:peptide complexes is facilitated by HLA-DM. Two unique mAbs, specific for I-Ab bound to human CLIP and I-Ab bound to DR alpha peptide, were used to assess the formation of these peptide:class II complexes in a human B lymphoblastoid cell line (B-LCL) (Swei) transfected with I-A(b). In multiple independent Swei:I-Ab transfectants, the amount of human CLIP (hCLIP):I-Ab expressed was inversely proportional to the amount of DR alpha 52-68:I-Ab; quantitative differences in HLA-DM expression accounted for this phenotype. In the low DM transfectant, a substantial proportion of I-Ab, but not DR molecules, was altered structurally and unable to present native protein Ags. Addition of DM transgenes to the DM-low cells resulted in an increase in DR alpha 52-68:I-Ab coupled with a decrease in hCLIP:I-Ab complexes and restoration of exogenous protein Ag presentation. The DR5 molecules in Swei cells, which have a lower affinity for hCLIP than I-Ab, were not affected by low DM expression, suggesting that the amount of DM required for conversion of CLIP:class II to peptide:class II may depend on the affinity of the class II molecules for CLIP or DM.

A study of complexes of class II invariant chain peptide: major histocompatibility complex class II molecules using a new complex-specific monoclonal antibody

Complexes of major histocompatibility complex (MHC) class II molecules containing invariant chain (Ii)-derived peptides, known as class II-associated invariant chain peptides (CLIP), are expressed at high levels in presentation-deficient mutant cells. Expression of these complexes in mutant and wild-type antigen-presenting cells suggests that they represent an essential intermediate in the MHC class II antigen-presenting pathway. We have generated a monoclonal antibody, 30-2, which is specific for these complexes. Using this antibody, we have found quantitative differences in CLIP:MHC class II surface expression in mutant and wild-type cells. Our experiments also show that CLIP:MHC class II complexes are preferentially expressed on the cell surface similar to total mature MHC class II molecules. These complexes are found to accumulate in the endosomal compartment in the process of endosomal Ii degradation. Analysis of the fine specificity of the antibody indicates that these complexes have Li peptide bound to the peptide-binding groove.

Population analysis of protection by HLA-DR and DQ genes from insulin-dependent diabetes mellitus in Swedish children with insulin-dependent diabetes and controls

A negative association between insulin-dependent diabetes mellitus (IDDM) and HLA-DR, DQA1 or DQB1 was found in a large population-based investigation of childhood-onset patients (more than 420 patients) and controls (more than 340 controls) from Sweden. The relative risk was decreased for several haplotypes that were negatively associated with IDDM: DR15-DQA1*0102-DQB1*0602, DR7-DQA1*0201-DQB1*0303, DR14-DQA1*0101-DQB1*0503, DR11-DQA1*0501-DQB1*0301, DR13-DQA1*0103-DQB1*0603 and DR4-DQA1*0301-DQB1*0301. In a relative predispositional effect (RPE) analysis, however, only the DR15-DQA1*0102-DQB1*0602 haplotype was significantly decreased, which suggests that the major protective effect for IDDM is carried by this haplotype. This was supported by the observation that all genotypes which were negatively associated with IDDM, except DR7/13, included at least one allele from the DR15-DQA1*0102-DQB1*0602 haplotype. Relative predispositional effect (RPE) analysis of genotypes showed further that the DR15-DQA1*0102-DQB1*0602 haplotype was also negatively associated with IDDM when combined with any other haplotype, whether negatively or positively associated with IDDM. This supports previous suggestions that DR15-DQA1*0102-DQB1*0602 acts dominantly. However, both the stratification and the predispositional allele test failed to distinguish the negative association between IDDM and DR15 from that of DQB1*0602. On the other hand, these tests indicated that DQA1*0102 was not likely to explain the negative association between IDDM and the DR15-DQA1*0102-DQB1*0602 haplotype. We conclude that the major protective effect for IDDM in the population of Swedish children is conferred by the DR15-DQA1*0102-DQB1*0602 haplotype in a dominant fashion, the DQB1*0602 allele being the allele most likely to be responsible for the protective effect of this haplotype, although an effect of the DR15 allele could not be excluded.

T cell recognition of major histocompatibility complex class II complexes with invariant chain processing intermediates

Peptides from the lumenal portion of invariant chain (Ii) spanning residues 80-106 (class II-associated Ii peptide [CLIP]) are found in association with several mouse and human major histocompatibility complex (MHC) class II allelic variants in wild-type and presentation-deficient mutant cells. The ready detection of these complexes suggests that such an intermediate is essential to the MHC class II processing pathway. In this study, we demonstrate that T cells recognize CLIP/MHC class II complexes on the surface of normal and mutant cells in a manner indistinguishable from that of nominal antigenic peptides. Surprisingly, T cell hybrids specific for human CLIP bound to murine MHC class II molecule I-Ab and a new monoclonal antibody 30-2 with the same specificity, recognize two independent epitopes expressed on this peptide/class II complex. T cell recognition is dependent on a Gln residue (position 100) in CLIP, whereas the 30-2 antibody recognizes a Lys residue-at position 90. These two residues flank the 91-99 sequence that is conserved among human, mouse, and rat Ii, potentially representing an MHC class II-binding site. Our results suggest that the COOH-terminal portion of CLIP that includes TCR contact residue Gln 100 binds in the groove of I-Ab molecule. Moreover, both T cells and the antibody recognize I-Ab complexed with larger Ii processing intermediates such as the approximately 12-kD small leupeptin-induced protein (SLIP) fragments. Thus, SLIP fragments contain a CLIP region bound to MHC class II molecule in a conformation identical to that of a free CLIP peptide. Finally, our data suggest that SLIP/MHC class II complexes are precursors of CLIP/MHC class II complexes.

Determination of human immunodeficiency virus RNA in plasma and cellular viral DNA genotypic zidovudine resistance and viral load during zidovudine-didanosine combination therapy

Eleven human immunodeficiency virus (HIV)-infected subjects on long-term zidovudine (ZDV) therapy had didanosine (ddI) added to their antiretroviral regimen. HIV RNA in plasma was quantitated by branched-DNA signal amplification assay. Peripheral blood mononuclear cell (PBMC) HIV viral DNA was quantitated by PCR. The relative amounts of wild-type (WT) sequence, ddI resistance-associated codon changes (reverse transcriptase [RT] gene codon 65 K-->R [RT K65R], RT 174V, RT I135K/T/V, and RT M184I/V), and ZDV resistance-associated codon change (RT T215Y/F) from HIV RNA in plasma and RT T215Y/F from PBMC viral DNA were determined by differential hybridization of PCR products from 10 of 11 subjects. All subjects had evidence of RT T215Y/F mutation in both RNA in plasma and PBMC DNA at baseline. Subjects with a mixture of WT and RT T215Y/F HIV RNA in plasma at baseline demonstrated a decline in RNA levels in plasma after the addition of ddI. However, after 6 months of ZDV-ddI therapy, WT HIV RNA in plasma was undetectable in all subjects who had demonstrated a mixture at baseline. Subjects with only RT T215Y/F RNA present in plasma at baseline remained so and demonstrated no decline in RNA levels in plasma. In all subjects, no significant changes in PBMC DNA viral load and RT T215Y/F or WT levels were seen. HIV RNA in plasma demonstrated a significantly higher RT T215Y/F mutant/WT ratio than that of PBMC viral DNA, both at baseline and after ZDV-ddI combination therapy in all subjects. No subjects developed mutations associated with ddI resistance at codons 65, 74, 135, and 184 during this study. This study suggests that determination of relative amounts of RT T215Y/F and WT species from HIV RNA in plasma at baseline may be predictive of virologic response during ZDV-ddI combination therapy.

Intracellular assembly and transport of endogenous peptide-MHC class II complexes

To define the intracellular site of assembly of endogenous peptide-MHC class II complexes, an immunochemical approach was undertaken employing a monoclonal antibody specific for an endogenous peptide-class II complex in combination with subcellular fractionation. Here, we show that newly synthesized MHC class II molecules, upon exit from the Golgi, are delivered into a dense endocytic compartment (MIIC) distinct from late endosomes and lysosomes. Endogenous peptide-class II complexes are initially formed in this compartment and subsequently traffic through late endosomal vesicles prior to cell surface expression. Exogenous antigen delivered via immunoglobulin receptors is targeted to MIIC en route to lysosomes after passing through early and late endosomes. Processing of an endocytosed antigen was observed in this compartment. Our results suggest a specific role for MIIC in the processing of endogenous and exogenous proteins as well as the assembly of peptide-MHC class II complexes.

HLA DR and DQ RFLP analysis in Crohn's disease

A study of 109 Swedish patients and 85 healthy Swedish controls with Crohn's disease (CD) by HLA class II RFLP genotyping was carried out. There was no significant association for any single DR or DQ specificity or phenotypic combination of DR and/or DQ specificities among our study group of Caucasian extraction.

Analysis of HLA-DQA1 and -DQB1 genes in Mexican Americans with insulin-dependent diabetes mellitus

Mexican American patients (n = 35) with insulin-dependent diabetes mellitus (IDDM) and control subjects (n = 39) were HLA-DQA and DQB typed by the polymerase chain reaction technique combined with allele-specific oligonucleotide probes. Either DQB1*0302 or DQB1*0201 was present among 91% (32/35) of the patients compared to 67% (26/39) of controls. Either DQA1*0501 or DQA1*0301 was present in all patients (100% or 35/35) compared to 29/39 (74%) (OR 12.06 Pc < 0.05) of controls. All four of these genes, in cis or trans, were present in 15/35 (43%) of the patients compared to 3/39 (8%) of controls (OR 9.0; Pc < 0.01). The presence of one or more non-susceptibility alleles showed a dose-related decrease in relative risk. Presence of aspartic acid (Asp) at position 57 of the DQ beta chain did not confer protection and non-Asp homozygosity did not confer susceptibility to IDDM in this ethnic group. In conclusion, susceptibility to IDDM in Mexican Americans is associated with particular DQA and DQB combinations, illustrates dose-dependent parameters and contradicts the critical residue hypothesis.

Decreased weight gain in BB rats before the clinical onset of insulin-dependent diabetes

Inbred specific pathogen-free diabetes-prone (DP) and diabetes-resistant (DR) BB rats were crossed to produce F1 and intercrossed to produce F2 rats. Diabetes segregates in these crosses as a recessive trait on rat chromosome 4. The weight gain of genetically diabetes-prone rats born to F1 healthy parents was studied to avoid effects of maternal diabetes. The weight gain of the F2 rats was initially not different from the F1 parents. The F2 rats later developing diabetes grew in parallel with their non-affected siblings up until the last 9 days before onset. During these 9 days they showed a decreased weight gain compared to their healthy litter-mates regardless of age. We conclude that decreased weight gain precedes the abrupt clinical onset of diabetes in BB rats and that it may be due to processes associated with the selective loss of beta cells.

Diabetes segregates as a single locus in crosses between inbred BB rats prone or resistant to diabetes

Diabetes-prone (DP) BB rats spontaneously develop insulin-dependent diabetes resembling type 1 diabetes mellitus in man. They also exhibit lifelong T cell deficiency. The segregation of both diabetes and lymphopenia was studied in crosses between this inbred line of rats and the related but nondiabetic and nonlymphopenic inbred diabetes-resistant (DR) BB rat line. Diabetes segregated as a single, autosomal recessive trait and was always accompanied by lymphopenia. Among the limited number of differences in the genomic DNA sequences of the two lines, DP and DR BB, one may account for the development of diabetes and lymphopenia in the DP BB rats. It may be possible to screen the genomic DNA for such differences to detect a marker for the phenotypes.

Leukocytosis at the onset of diabetes in crosses of inbred BB rats

Inbred lymphopenic, diabetes-prone (DP) and non-lymphopenic, diabetes-resistant (DR) BB rats in a specific pathogen-free (SPF) colony were subjected to a cross-intercross breeding experiment which showed diabetes to segregate as a recessive trait. All DP rats, but none of the DR and F1 rats, developed diabetes. In contrast, about 25% of the F2 rats developed diabetes which made it possible to study these rats without maternal influence of diabetes. All rats were bled at regular intervals between 30 and 150 days of age, and the samples analyzed for numbers of leukocytes, lymphocytes, neutrophils, monocytes and eosinophils. Leukocyte numbers tended to increase with age until about 100 days, and to decline thereafter. Males had more leukocytes than females. Coinciding with the time of onset of overt diabetes, there was a large increase in eosinophils, along with smaller increases in neutrophils, monocytes and lymphocytes. These data in SPF DP and DR BB rats and their cross-intercross offspring demonstrate that the overt onset of diabetes is associated with a significant leukocytosis.