Investigation of Mitochondrial Related Variants in a Cerebral Small Vessel Disease Cohort

Monogenic forms of cerebral small vessel disease (CSVD) can be caused by both variants in nuclear DNA and mitochondrial DNA (mtDNA). Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is known to have a phenotype similar to Cerebral Autosomal Dominant Arteriopathy with Sub-cortical Infarcts and Leukoencephalopathy (CADASIL), and can be caused by variants in the mitochondrial genome and in several nuclear-encoded mitochondrial protein (NEMP) genes. The aim of this study was to screen for variants in the mitochondrial genome and NEMP genes in a NOTCH3-negative CADASIL cohort, to identify a potential link between mitochondrial dysfunction and CSVD pathology. Whole exome sequencing was performed for 50 patients with CADASIL-like symptomology on the Ion Torrent system. Mitochondrial sequencing was performed using an in-house designed protocol with sequencing run on the Ion GeneStudio S5 Plus (S5 +). NEMP genes and mitochondrial sequencing data were examined for rare (MAF < 0.001), non-synonymous variants that were predicted to have a deleterious effect on the protein. We identified 29 candidate NEMP variants that had links to either MELAS-, encephalopathy-, or Alzheimer’s disease–related phenotypes. Based on these changes, variants affecting POLG, MTO1, LONP1, NDUFAF6, NDUFB3, and TCIRG1 were thought to play a potential role in CSVD pathology in this cohort. Overall, the exploration of the mitochondrial genome identified a potential role for mitochondrial related proteins and mtDNA variants contributing to CSVD pathologies.

Investigating diagnostic sequencing techniques for CADASIL diagnosis

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a cerebral small vessel disease caused by mutations in the NOTCH3 gene. Our laboratory has been undertaking genetic diagnostic testing for CADASIL since 1997. Work originally utilised Sanger sequencing methods targeting specific NOTCH3 exons. More recently, next-generation sequencing (NGS)-based technologies such as a targeted gene panel and whole exome sequencing (WES) have been used for improved genetic diagnostic testing. In this study, data from 680 patient samples was analysed for 764 tests utilising 3 different sequencing technologies. Sanger sequencing was performed for 407 tests, a targeted NGS gene panel which includes NOTCH3 exonic regions accounted for 354 tests, and WES with targeted analysis was performed for 3 tests. In total, 14.7% of patient samples (n = 100/680) were determined to have a mutation. Testing efficacy varied by method, with 10.8% (n = 44/407) of tests using Sanger sequencing able to identify mutations, with 15.8% (n = 56/354) of tests performed using the NGS custom panel successfully identifying mutations and a likely non-NOTCH3 pathogenic variant (n = 1/3) identified through WES. Further analysis was then performed through stratification of the number of mutations detected at our facility based on the number of exons, level of pathogenicity and the classification of mutations as known or novel. A systematic review of NOTCH3 mutation testing data from 1997 to 2017 determined the diagnostic rate of pathogenic findings and found the NGS-customised panel increases our ability to identify disease-causing mutations in NOTCH3.

A novel route to substituted 4-methylene-4,5-dihydroisoxazoles mediated by hafnium(IV) chloride

Heating alkyl vinyl ketones and N-tert-butylarylmethylideneamine N-oxides in the presence of HfCl4 results in the formation of 4-methylene-4,5-dihydroisoxazoles in good yield.

The shape of 433 eros from the NEAR-shoemaker laser rangefinder

Measurements from the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker Laser Rangefinder (NLR) indicate that asteroid 433 Eros is a consolidated body with a complex shape dominated by collisions. The offset between the asteroid's center of mass and center of figure indicates a small deviation from a homogeneous internal structure that is most simply explained by variations in mechanical structure. Regional-scale relief and slope distributions show evidence for control of topography by a competent substrate. Impact crater morphology is influenced by both gravity and structural control. Small-scale topography reveals ridges and grooves that may be generated by impact-related fracturing.

A whole-genome assembly of Drosophila

We report on the quality of a whole-genome assembly of Drosophila melanogaster and the nature of the computer algorithms that accomplished it. Three independent external data sources essentially agree with and support the assembly's sequence and ordering of contigs across the euchromatic portion of the genome. In addition, there are isolated contigs that we believe represent nonrepetitive pockets within the heterochromatin of the centromeres. Comparison with a previously sequenced 2.9- megabase region indicates that sequencing accuracy within nonrepetitive segments is greater than 99. 99% without manual curation. As such, this initial reconstruction of the Drosophila sequence should be of substantial value to the scientific community.

Genomic strategies for defining and dissecting developmental and physiological pathways

A major challenge in genetics research is defining and dissecting the diversity of developmental and physiological pathways that lie between genes and traits. New functional genomics methods are transforming these studies by providing comprehensive and systematic approaches that complement traditional methods of formal genetics, biochemistry, and cell biology. Together, these complementary approaches will test whether reductionism can account for the complex web of interactions that lead from genetic variation to morphological, physiological, and behavioral traits in health and disease.

Current state of metabolic control achieved in a New Zealand diabetes clinic

AIMS

To report on current degree of metabolic control achieved in diabetic patients in a New Zealand diabetes clinic.

METHODS

All metabolic data were reviewed for patients attending the Waikato diabetes clinic from 1 January 1992 to 1 January 1995. Values were obtained from 409 insulin treated patients (IDDM), with a mean age of 39 (SD 15 yr); 200 patients who transferred from diet or pills to insulin (NIDDM-I) with a mean age of 59 (SD 12 yr); and 290 noninsulin dependent patients (NIDDM), mean age 54 (SD 13 yr). Results. Percentage of fructosamine values in the normal range: IDDM 10%, NIDDM-I 12.5% and NIDDM 37.9%. Mean values (SD). IDDM group: fructosamine 376 (78) mmol/L, cholesterol 5.24 (1.1) mmol/L, HDL cholesterol 1.47 (0.45) mmol/L, triglycerides 1.71 (1.35) mmol/L. NIDDM-I group: fructosamine 359 (67) mmol/L, cholesterol 5.82 (1.1) mmol/L, HDL cholesterol 1.21 (0.45) mmol/L, triglycerides 2.92 (3.8) mmol/L. NIDDM group: fructosamine, 312 (73) mmol/L, cholesterol 5.83 (1.24) mmol/L, HDL cholesterol 1.1 (0.33) mmol/L, triglycerides 3.11 (3.59) mmol/L. Percentage of smokers in each group: IDDM 24%, NIDDM-I 8.5%, NIDDM 17.2%.

CONCLUSIONS

the majority of patients fail to achieve normal fructosamine values. Lipid control is poor, other than in the IDDM group. A significant number of patients continue to smoke. Considerable scope for improvement is noted.

The prognostic significance of urinary albumin in Polynesians with non-insulin-dependent diabetes

Polynesian (59 Maori and 30 Pacific Island) patients were identified from two diabetes clinic registers and followed for a mean of 4.8 years, in order to determine the prognostic significance of urinary albumin excretion. Events were defined as death or entry onto a renal replacement programme. Fourteen events occurred during the period of follow-up. Urinary albumin/creatinine ratio was treated as a continuous variable in a proportional hazards analysis. A 10-fold increase in albumin/creatinine ratio was associated with a 5-fold increase in the risk of an event (95% C.I. = 2.05-12.09). In conclusion, elevated urinary albumin/creatinine predicted mortality and renal morbidity in Maori and Pacific Island patients with non-insulin-dependent diabetes.

Discover diabetes: a community based screening programme for diabetic eye disease

AIM

To evaluate a diabetic retinopathy screening programme for rural people with diabetes.

METHOD

A retinal camera was transported to rural Waikato communities. Colour slide photographs were taken of the retina and lens of diabetic patients who had not had a previous review of their eyes by an ophthalmologist. The photographs were reviewed by an ophthalmologist, and those patients with an abnormality were referred back to their general practitioner who arranged further specialist assessment.

RESULTS

Three hundred and ninety six patients have been screened and 116 patients have been referred on for specialist review. Fifty two of these patients had evidence of diabetic retinopathy, eight have been treated with laser treatment and one patient has had retinal surgery. No patients had to be recalled for repeat photographs.

CONCLUSION

Retinal photography is an effective method of screening for sight threatening pathology in rural people with diabetes. Transportation of the retinal camera by station wagon is a practical way of making the service accessible.

Discover diabetes: screening for diabetes mellitus in the Waikato

AIMS

Free screening for diabetes mellitus was offered, in three rural communities as part of an initiative of the Waikato Area Health Board to improve the detection and management of type 2 diabetes.

METHOD

An organised campaign promoted glucose testing as an important preventative health measure for 'at risk' members of the community. At risk was defined as being either Maori over 20 years of age, European over 40 years of age, obese or having a family history of diabetes. The testing method was a random capillary glucose test followed by an oral glucose tolerance test for those with a result > or = 8 mmol/L.

RESULTS

Five thousand five hundred and eighty nine people voluntarily attended screening at various sites. Sixty of these people were already known to have diabetes and were subsequently excluded. One thousand and four people had no recognised risk factors. Four thousand five hundred and twenty one people with risk factors for type 2 diabetes had a capillary blood glucose test and 162 were found to have a capillary glucose greater than 8 mmol/L. Four patients did not have their glucose result recorded. One hundred and forty one oral glucose tolerance tests were performed and 56 new patients with diabetes were identified based on WHO criteria for diabetes. The prevalence of previously undiagnosed diabetes was higher in those over 50 years of age, particularly if they were Maori. It was also higher in obese Maori in the 30-49 year age group.

CONCLUSIONS

Although over 5000 patients attended screening, this testing included only 34% of the at risk age group. Thus voluntary testing, despite a major investment in promotion, proved ineffective as a population screening tool. A random capillary glucose test proved to be a simple and sensitive method of helping to identify previously undiagnosed disease. This could be effectively used by general practitioners, targeting all adults over 50 years of age, and all adult Maori with obesity as defined by a BMI > or = 30.

Assessment of Micral-Test microalbuminuria test strip in the laboratory and in diabetic outpatients

We have evaluated a semi-quantitative dry immunochemical screening method (Micral-Test) for the detection of low concentrations of albumin in urine. The stability of Micral-Test strips on storage was good, especially with regard to temperature, light and humidity. Changes in urine osmolality (urea and creatinine concentration), pH and sodium and potassium concentration did not have a significant analytical effect on the Micral-Test measurement; extremes of temperature altered the rate of colour development. The depth of dipping the strip into the sample and the timing of reading colour development were critical. We measured the albumin concentration in 184 urine samples from diabetic outpatients by the Micral-Test and by our in-house immunoturbidimetric method; a Micral-Test result of 20 mg/L had a sensitivity of 91% and specificity of 97% to predict a discriminating urine albumin concentration greater than 30 mg/L by the in house method. The Micral-Test is suitable for use by non-laboratory personnel and is capable of producing analytically acceptable results for use in diabetes clinics and by general practitioners.

Random urine albumin:creatinine ratio measurements as a screening test for diabetic microalbuminuria--a five year follow up

Serial random urine samples have been collected from 167 insulin treated diabetic patients attending the Waikato diabetes clinic from 1984 to 1989 and albumin/creatinine ratios measured as a screening test for diabetic microalbuminuria. The group ranged in age from 12 to 50 years and comprised 79 males and 88 females. Where the initial test was normal (less than 2.5), as found in 117 patients, 86.7% of all tests over the five year period (1032) remained normal. Of 50 patients with an initial elevated value, 39% of a total of 575 values taken over the five year period were subsequently normal.

CONCLUSION

a random urine albumin measurement taken at yearly intervals is an adequate screening programme for patients with an initial normal value.

Androgen and oestrogen receptor status in benign and neoplastic prostate disease. Study of prevalence and influence on time to progression and survival in prostate cancer treated by hormone manipulation

TUR chips from 89 men were analysed prospectively for androgen and oestrogen nuclear and cytoplasmic receptors (ANR, ACR, ONR, OCR). Patients were selected on the basis of suspicion of neoplastic change on clinical feel of the prostate. A control group of benign cases was also collected prospectively. Histological examination showed that 46 patients had prostatic carcinoma and 43 had benign prostatic hyperplasia. No difference was found between the 2 groups in terms of prevalence of any of the receptors or in levels of receptor in those who were positive. The patients with neoplastic changes were followed up for a median of 53 months (range 47-64). No significant effect on duration of survival was noted with any of the receptor variables but there was a beneficial association between cytoplasmic oestrogen receptor positivity and progression-free interval. Patients with T category 3 or 4 had a significantly higher chance of being ANR positive than those of lower T category and this may reflect sampling error. There appears to be some evidence to suggest that cytosol oestrogen receptor positivity has a prognostic role in prostate cancer, in terms of time to progression on hormone therapy. Receptor status did not influence survival.

Familial generalised resistance to thyroxine: case study

We describe the clinical features of members of a family with an atypical form of thyroid hormone resistance syndrome, affecting thyroxine predominantly. Relevant diagnostic clinical and biochemical investigations are outlined and discussed.

Urine albumin creatinine ratio and clinical correlates in a diabetic population

The urine albumin/creatinine ratio was measured in random urine samples in a range of diabetic subjects as a guide to urinary albumin excretion rate in diabetic patients. In 74 control subjects the 95th percentile for the albumin/creatinine ratio was 1.3. In 39 diabetic patients the random urine albumin/creatinine ratio correlated highly with the 24 hour urine albumin excretion (r = 0.9371, p less than 0.001). In 337 insulin treated diabetic subjects 55% of the female and 39% of the male values exceeded 1.3. In 98 noninsulin treated diabetic subjects 67% of female and 62% of male values exceeded 1.3. Selecting albumin/creatinine ratios between 2.5 to 26.8 corresponding to albumin excretion rates between 20 mg and 250 mg/day, 26.1% of the insulin treated group were in this microalbuminuric range, and 8.7% had overt albuminuria. Higher figures were seen in the noninsulin treated group. Within these two large diabetic groups significant associations (p less than 0.005) were seen with glycaemia, blood pressure, body mass index, retinopathy and duration of diabetes. We believe that measurement of albumin/creatinine ratios on random urine samples offers a simple and convenient way of monitoring albumin excretion in large numbers of diabetic patients.

Laboratory assessment of a commercial kit for measuring fructosamine in serum

We have evaluated the laboratory performance and clinical usefulness of the Roche fructosamine kit. As used with an Abbott ABA 100 bichromatic analyzer, the kit response varied linearly with fructosamine concentration to 5.0 mmol/L (deoxymorpholinofructose equivalents). Interbatch precision was 4.1% and 3.6% for respective fructosamine concentrations of 3.2 and 5.0 mmol/L; intrabatch precision was 3.2% and 3.0% (fructosamine = 3.0 and 4.0 mmol/L). In 55 nondiabetic subjects all fructosamine values were less than 3.0 mmol/L, 95% were less than 2.7 mmol/L. For both fructosamine and glycated hemoglobin (Hb A1c) the 95th percentile of the reference range corresponded to approximately the 10th percentile of values observed in 108 diabetic subjects. In the latter subjects fructosamine concentrations correlated somewhat (r = 0.6504) with the Hb A1c value and for eight diabetic subjects indicated a similar degree of diabetic control over a 10-week period. From assessments of sensitivity and specificity for predicting abnormal glucose tolerance in 145 subjects, we conclude that this assay of serum fructosamine reflects diabetic control about as well as Hb A1c estimation, but neither can replace the glucose tolerance test for the diagnosis of diabetes.

Laboratory assessment of a commercial kit for measuring fructosamine in serum

We have evaluated the laboratory performance and clinical usefulness of the Roche fructosamine kit. As used with an Abbott ABA 100 bichromatic analyzer, the kit response varied linearly with fructosamine concentration to 5.0 mmol/L (deoxymorpholinofructose equivalents). Interbatch precision was 4.1% and 3.6% for respective fructosamine concentrations of 3.2 and 5.0 mmol/L; intrabatch precision was 3.2% and 3.0% (fructosamine = 3.0 and 4.0 mmol/L). In 55 nondiabetic subjects all fructosamine values were less than 3.0 mmol/L, 95% were less than 2.7 mmol/L. For both fructosamine and glycated hemoglobin (Hb A1c) the 95th percentile of the reference range corresponded to approximately the 10th percentile of values observed in 108 diabetic subjects. In the latter subjects fructosamine concentrations correlated somewhat (r = 0.6504) with the Hb A1c value and for eight diabetic subjects indicated a similar degree of diabetic control over a 10-week period. From assessments of sensitivity and specificity for predicting abnormal glucose tolerance in 145 subjects, we conclude that this assay of serum fructosamine reflects diabetic control about as well as Hb A1c estimation, but neither can replace the glucose tolerance test for the diagnosis of diabetes.

Multiple dose insulin regimen using the NovoPen: initial experience and approximate dose requirements

We present our initial experience with a multiple dose per day insulin regimen using the newly developed multidose NovoPen insulin injector. Fourteen insulin dependent diabetic patients were studied, 6 with excellent control and 8 with poor control on twice a day conventional insulin injection regimens. Total insulin dosage per day remained the same on the new compared to the old regimen; 0.71 (SD) 0.22 versus 0.73 (0.23) units/kg per day. Mean blood glucose control as evidenced by HbA1% values did not alter significantly in the well controlled group, but improved significantly in the poorly controlled group. Frequency of hypoglycaemia appeared to be reduced on the multiple dose regimen in particular in two of the subjects with excellent blood glucose control. The NovoPen proved to be reliable and convenient and was well accepted by all but one subject.

Adrenal function in acute severe asthma

Adrenocortical function was assessed by the intravenous short synacthen test in 22 control subjects and 68 patients admitted to hospital with acute severe asthma. The cortisol increment was subnormal in 19 of the 68 asthmatics. This included 11 of the 14 patients on continuous oral steroids, seven of the 29 patients who had had occasional courses of oral steroids, one of the seven on inhaled steroids only, and none of the 18 who had had no steroids. Adrenal suppression was greatest in those patients taking oral steroids in divided daily doses. Nineteen of 43 patients were on or had taken oral steroids in this fashion. Of those 19 patients with low cortisol increments only one half had received supplementary steroids in the 24 hours preceding admission. Based on the synacthen test, serum DHEA-SO4 values were not a good discriminant of adrenocortical function. Adrenal insufficiency may be an important cause of death in acute severe asthma in New Zealand.

Outcome of diabetic pregnancies in Waikato: five year experience

The outcome of diabetic pregnancies in Waikato Hospital from 1979-1984 was reviewed. Overall perinatal mortality in the 61 deliveries was 69/1000 births but in the 38 deliveries whose antenatal care included close diabetic control, the perinatal mortality was 26/1000 births. The national perinatal mortality has improved from 12.2/1000 births in 1979 to 9.6/1000 in 1983 (provisional) with an overall rate of 11.0/1000 births. Improved outcome of diabetic pregnancies both in terms of reduced perinatal mortality and reduced neonatal and maternal complications depends on meticulous blood glucose control throughout pregnancy.

Dramatic and rapid shrinkage of a massive invasive prolactinoma with bromocriptine: a case report

Shrinkage of a massive, highly invasive, longstanding (probably 40 years) prolactin-secreting pituitary tumour is described in which tumour volume was reduced by 40% 8 d after beginning bromocriptine treatment. After 4 months of treatment the tumour was only 11% of the pretreatment volume and by 8 months it was further reduced in size being confined to the pituitary fossa, which was partially empty. Reduction in tumour volume was accompanied by a gradual reduction in serum prolactin concentrations to normal values at 4 months. Between 4 and 18 months serum prolactin has remained normal on 5 mg of bromocriptine daily. Visual function improved within 48 h of starting bromocriptine and was almost normal by 6 d. CSF rhinorrhoea developed as the tumour shrank and was successfully managed with the relatively minor procedure of a diversionary lumbo-peritoneal shunt. Bromocriptine should be considered as the initial treatment of choice for massive invasive prolactinomas because of the significant risk of morbidity from neurosurgical treatment.

Dehydroepiandrosterone sulphate concentrations in asthmatic patients: pilot study

Dehydroepiandrosterone sulphate (DHEA-SO4) values were measured as a guide to adrenal function in 72 asthmatic patients admitted to the Waikato Hospital with severe bronchospasm. In a reference sample 700 micrograms/l was taken as the lower limit of the reference range for DHEA-SO4 concentrations. All DHEA-SO4 values in 20 patients with known primary or secondary adrenal insufficiency were less than this value. In the asthmatic group, 10 of 14 DHEA-SO4 values were low in patients taking oral steroid therapy, eight of 23 values in patients taking inhaled steroids, and six of 29 values in patients on no known steroid therapy. Five of six patients who had been on oral steroids within a month of admission also had low values. In total 40% of all values were less than 700 micrograms/l. These data provide inferential evidence of possible adrenal suppression in a substantial number of patients requiring hospital admission for treatment of severe bronchospasm.

Pancreatic endocrine tissue in benign mediastinal teratoma

Four cases of benign cystic mediastinal teratoma containing pancreatic tissue have been studied using immunohistochemical and morphometric techniques. The different pancreatic endocrine cell types were stained using antibodies to insulin, glucagon, somatostatin, and pancreatic polypeptide, and the volume density of each cell type was estimated by point counting. Sections from different regions of the normal adult pancreas were also examined and the results compared. There was an increased total volume density of endocrine cells in the teratomatous pancreas, with a pronounced increase in the proportion of somatostatin containing D cells. The results are similar to those described for pancreatic tissue in neonates, and it is suggested that this is further evidence of altered functional differentiation of the pancreatic tissue found in teratomas.

Pituitary adenomas producing growth hormone in acromegalic patients

Growth hormone was shown in histological sections of 25 pituitary adenomas from acromegalic patients by means of the unlabelled peroxidase-antiperoxidase (PAP) technique. On the basis of the numbers of cytoplasmic granules, the cells of the adenomas were of two types: densely granulated and sparsely granulated. The densely granulated cells had abundant cytoplasm containing numerous granules, whereas the sparsely granulated cells had little cytoplasm with scanty granules. Depending on the predominant cell type the adenomas were also classified as densely granulated or sparsely granulated: 21 of the 25 adenomas (84%) were densely granulated and four (16%) sparsely granulated. There was some variation, however, in the relative numbers of the two types of cell from one part of an adenoma to another, a feature consistent with one type of cell in different phases of activity. There was no significant difference in mean serum growth hormone concentrations between the two groups, and granularity of the adenomas in histological sections did not therefore correlate with secretory activity. Nine adenomas showed extrasellar extension. The mean serum growth hormone concentration in these cases was lower than the mean of the adenomas confined to the sella turcica. Thus the size of the tumour did not correlate with the serum growth hormone concentration. Three of the four adenomas in the sparsely granulated group showed extrasellar extension, compared with 6 of 21 classified as densely granulated. This suggests that sparsely granulated adenomas have a more aggressive pattern of behaviour, but histological evidence for this was lacking.

Clinical importance of the reversible fraction of haemoglobin A1c in Type 2 (non-insulin-dependent) diabetes

Two studies demonstrating the clinical relevance of the labile fraction of haemoglobin A1c are presented. Haemolysates, dialysed at 37 degrees C against 0.9% NaCl, showed an average decrease of haemoglobin A1c value of 7.0% of total glycosylated haemoglobin, post-dialysis. There was a close correlation between the pre- and post-dialysis haemoglobin A1c values (r = 0.9644). In four Type 2 (non-insulin-dependent) diabetic subjects, blood glucose and pre- and post-dialysis haemoglobin A1c values were determined at weekly intervals over an 18-week period, including 6 weeks when oral hypoglycaemic therapy was withheld. During this time, pre- and post-dialysis haemoglobin A1c values responded synchronously to changes in blood glucose concentration. The mean coefficient of variation of the pre- and post-dialysis haemoglobin A1c values did not differ significantly over the 18-week period. It is concluded that the routine elimination of the labile fraction of haemoglobin A1c is not necessary to assess control in Type 2 diabetes.

Recurrent insulinoma syndrome with metastatic glucagonoma

A case is reported of a patient who presented with symptomatic hypoglycaemia and who had three pancreatic tumours resected over the ensuing eight years. Immunocytochemistry demonstrated two of these to be insulinomas and the third to be a glucagonoma. In addition metastatic spread of cells positive for glucagon had occurred to a lymph node and multiple nodules staining positively for glucagon were present in the remainder of the pancreas.

Glycosylated haemoglobin: an overview of a series of clinical studies

A series of studies on the clinical relevance of chromatographically determined glycosylated haemoglobins is presented. Both whole blood samples and haemolysates were stable at 5 degrees C for up to two weeks. Prolonged storage required temperatures less than -80 degrees C. Haemoglobin (Hb) AIc percent values in non-diabetic subjects ranged from 4.0 to 6.0 percent (mean +/- 2 SD). HbAIc percent values proved to be as stable in diabetic as non-diabetic subjects on repetitive sampling over a three month period. A dissociable component was not observed in any of 78 samples. HbAIc percent values of carbohydrate intolerant subjects (n = 18) were not distinguishable from those in non-diabetic subjects. A close correlation was observed between HbAIc percent and the mean of multiple capillary glucose samples in 37 insulin dependent diabetic subjects. In clinical practice HbAic percent proved to be a stable objective measure of blood glucose concentrations in diabetic patients--the major present need is for a simple reliable technique of measurement.

Stability of hemoglobin AIc levels on repetitive determination in diabetic out-patients

Hemoglobin (Hb) AIc levels were measured biweekly for 14 weeks in 49 diabetic out-patients and 20 nondiabetic subjects. As conventional indices of diabetes control, urine tests were performed four times per day, and plasma glucose concentrations were measured 2 h post breakfast. The diabetic group ranged in age from 15-73 yr and in duration of diabetes from 6 months to 45 yr. Eleven subjects were on diet therapy alone, three were on oral hypoglycemic agents, and 35 were on insulin therapy. The nondiabetic group ranged in age from 18-65 yr. On entry to the study, the mean (+/-SD) Hb AIc and plasma glucose levels of the diabetic group (8.60 +/- 2.11% and 142.5 +/- 99.9 mg/dl) were significantly higher than in the control group (4.68 +/- 0.60% and 102.4 +/- 21.7 mg/dl; P less than 0.001) and remained so throughout the study. The mean coefficient of variation for Hb AIc did not differ significantly between the control group and either the diet therapy or insulin therapy diabetic groups. Urine test values averaged over 2-week periods for each diabetic subject showed a high degree of stability. The mean Hb AIc levels for individual diabetic subjects correlated with the mean plasma glucose levels (r = 0.544; P less than 0.001), proportion of 2% urine tests (r = -0.798; P less than 0.001). These data provide further support for Hb AIc as a measure of diabetes control and, in addition, provide the first direct evidence that a single Hb AIc determination in a 3-month period is adequate for this purpose when the subjects are on a stable therapeutic regimen.

Hemoglobin A1c compared with three conventional measures of diabetes control

Control of diabetes was studied during an 8-wk camp program in 18 insulin-dependent counselors with a mean age of 19.3 yr and a mean duration of diabetes of 11.4 yr. A composite score was obtained for each subject derived from three factors: percent sugar-free urine tests, 24-h glucose excretion as percent of carbohydrate intake, and mean preprandial blood glucose (MPBG). The mean hemoglobin A1c (HbA1c) at the end of the period was 8.3 +/- 1.6% (+/ SD) (normal range, 4-6%). Scores ranging from 24 (fair control) to 45 (excellent control) showed a significant inverse correlation with HbA1c (r = 0.807, P less than 0.001) and MPBG (r = -0.674, P less than 0.01). HbA1c showed a significant correlation with the MPBG (r = 0.693, P less than 0.01). The HbA1c level was predicted better by percent sugar-free urine tests than by the 24-h glucose excretion. Thus it appears that accurate quantification of control may be obtained by using a scoring system. Critical comparison of HbA1c levels to various glycemic indices may provide useful alternatives for estimating diabetes control.

The determination of glycosylated hemoglobins in rats using high pressure liquid chromatography

Glycosylated hemoglobins (GHb) or fast hemoglobins (FH) are minor components of hemoglobin that so far have been quantified in men, monkeys, and mice, and they are elevated in diabetic subjects of all these species. Since the rat is a useful model for experimental diabetic studies, hemolysates from streptozotocin-induced diabetic rats were analyzed for FH fractions using a high pressure liquid chromatography method. In a long-term study (3 mo), the maximal increment of the FH fractions was achieved after 5 wk of diabetes (from 5.67% +/- 0.41% SD to 10.80% +/- 0.74%) supporting the notion that the biosynthesis of these compounds occurs continuously during the lifespan of the red cell. In a short-term study, however, an elevation of the FH by 11% after 2 days and by 26% after 6 days of diabetes was noticed suggesting that a rapid increase of the FH may occur in relation to rapid changes of the glucose level.