Tumour morphology predicts PALB2 germline mutation status.

BACKGROUND: Population-based studies of breast cancer have estimated that at least some PALB2 mutations are associated with high breast cancer risk. For women carrying PALB2 mutations, knowing their carrier status could be useful in directing them towards effective cancer risk management and therapeutic strategies. We sought to determine whether morphological features of breast tumours can predict PALB2 germline mutation status. METHODS: Systematic pathology review was conducted on breast tumours from 28 female carriers of PALB2 mutations (non-carriers of other known high-risk mutations, recruited through various resources with varying ascertainment) and on breast tumours from a population-based sample of 828 Australian women diagnosed before the age of 60 years (which included 40 BRCA1 and 18 BRCA2 mutation carriers). Tumour morphological features of the 28 PALB2 mutation carriers were compared with those of 770 women without high-risk mutations. RESULTS: Tumours arising in PALB2 mutation carriers were associated with minimal sclerosis (odds ratio (OR)=19.7; 95% confidence interval (CI)=6.0-64.6; P=5 × 10(-7)). Minimal sclerosis was also a feature that distinguished PALB2 mutation carriers from BRCA1 (P=0.05) and BRCA2 (P=0.04) mutation carriers. CONCLUSION: This study identified minimal sclerosis to be a predictor of germline PALB2 mutation status. Morphological review can therefore facilitate the identification of women most likely to carry mutations in PALB2.

Lack of evidence for neutrophil participation during infarct formation following focal cerebral ischemia in the rat.

The involvement of neutrophils in the pathogenesis of cerebral ischemic injury in two rat models of focal ischemia was investigated. In Experiment I, a model of focal ischemia with partial reperfusion was used. Although significant and discrete ischemic damage within the neocortex was nearly maximal at 12 h postocclusion, no elevation in neutrophils was seen at this time point. Even after 21 h postocclusion, only a subtle increase in neutrophils within the ischemic tissue was observed. To further investigate the possible role of neutrophils in cerebral ischemia, the effect of cyclophosphamide-induced neutropenia was investigated (Experiment II). While a marked reduction (>98%) in systemic neutrophils was achieved in advance of and during the ischemic challenge, no reduction in the volume of ischemic damage was observed. In Experiment III, variations in the rat model of focal ischemia were made to produce a larger area of ischemic damage, as well as to permit complete reperfusion of blood to the affected cortex. While more neutrophils were seen in this variation of the model, very few were observed (< 1 per field) prior to the time that maximal ischemic damage had already occurred. Together, these experiments revealed that substantial brain necrosis occurred prior to the appearance of neutrophils, under conditions of partial, as well as complete, reperfusion. Moreover, at the time points when elevations in neutrophils were observed, no further increase in volume of ischemic damage was noted. Finally, pharmacologic removal of neutrophils prior to ischemia did not alter the size of the ischemic region. These data therefore fail to support the hypothesis that neutrophils play a general and essential role in infarct formation following focal brain ischemia and argue that further studies are required to more clearly elucidate the conditions under which neutrophils might participate in ischemic pathogenesis.

Calpain inhibitor AK295 protects neurons from focal brain ischemia. Effects of postocclusion intra-arterial administration.

BACKGROUND AND PURPOSE: This research was performed to determine whether a selective inhibitor of the calcium-dependent protease, calpain, could reduce ischemia-associated brain damage when peripherally administered after a vascular occlusion. METHODS: A variation of the rat middle cerebral artery occlusion model was used. A range of doses of AK295 (a novel calpain inhibitor synthesized for this purpose) was continuously infused through the internal carotid artery, beginning 1.25 hours from the initiation of the occlusion. Rats were killed at 21 hours, and the infarct volume was quantified. RESULTS: Postocclusion (1.25-hour) infusion of the calpain inhibitor AK295 elicited a dose-dependent neuroprotective effect after focal ischemia. The highest dose tested (3 mg/kg per hour) afforded the maximum effect, illustrated by a 32% reduction in infarct volume 21 hours after the ischemia (vehicle, 81.7 +/- 4.7 mm3; AK295, 54.9 +/- 6.9 mm3; P < .007). CONCLUSIONS: These data provide the first evidence that a peripherally administered calpain inhibitor can protect against ischemic brain damage. They offer further support for an important role of calpain proteolysis in the brain degeneration associated with cerebral ischemic events and suggest that selective calpain inhibitors provide a rational, novel, and viable means of treating such neurodegenerative problems.

The effect of 3 months of recombinant human growth hormone (GH) therapy on insulin and glucose-mediated glucose disposal and insulin secretion in GH-deficient adults: a minimal model analysis.

The effect of 3 months of low dose (120 micrograms/kg.week or 0.24 IU/kg.week) recombinant human GH (rhGH) treatment on glucose tolerance, insulin secretion, and insulin- and glucose-mediated glucose disposal was examined in 10 GH-deficient adults. The frequently sampled iv glucose tolerance test was performed at baseline and after 1 week and 3 months of rhGH therapy and analyzed by the minimal model method of Bergman to provide estimates of the glucose decay rate, first and second phase insulin secretion (phi 1 and phi 2), fractional clearance of insulin, and glucose-mediated and insulin-mediated glucose disposal. Fasting glucose, insulin, C-peptide, nonesterified fatty acids (NEFA), and serum cholesterol and triglycerides were also measured. When the 1 week data were compared to baseline, there was a small but significant rise in mean (+/- SE) fasting glucose (4.62 +/- 0.17 vs. 5.1 +/- 0.15 mmol/L; P < 0.01), NEFA (0.70 +/- 0.09 vs. 1.1 +/- 0.12 mmol/L; P < 0.005), insulin (93.6 +/- 8.9 vs. 238.9 +/- 9.2 pmol/L; P < 0.0001), C-peptide (0.32 +/- 0.13 vs. 0.66 +/- 0.13 nmol/L; P < 0.005), and phi 1 (11.9 +/- 1.3 vs. 16.2 +/- 1.8 pmol/L.min/mmol.L x 10(2)) and phi 2 (1.43 +/- 0.17 vs. 3.15 +/- 0.25 pmol/L.min/mmol.L x 10(3); P < 0.05). Conversely, there were associated decreases in glucose decay rate (1.83 +/- 0.26 vs. 1.28 +/- 0.12 min-1; P < 0.05) and insulin-mediated glucose disposal (0.36 +/- 0.08 vs. 0.18 +/- 0.06 min/pmol.L x 10(-4); P < 0.005). There was no change in glucose-mediated glucose disposal or the fractional clearance of insulin. By 3 months, fasting insulin and C-peptide levels remained significantly elevated, whereas other parameters had returned to baseline. There was a minor reduction in serum cholesterol at 1 week (5.1 +/- 0.15 vs. 4.62 +/- 0.17 mmol/L; P < 0.01), which was not maintained at 3 months. Serum triglycerides remained unchanged throughout the study. We conclude that short term low dose rhGH treatment of GH-deficient adults induces a temporary state of mild glucose intolerance, hyperinsulinemia, insulin resistance, and raised NEFA levels at 1 week. By 3 months, these metabolic disturbances had returned to baseline for a persisting modest hyperinsulinemia. Whether this hyperinsulinemia will last over the longer term and/or has distant detrimental metabolic consequences in the individual must await further studies.

Postischemic administration of AK275, a calpain inhibitor, provides substantial protection against focal ischemic brain damage.

Experiments were conducted to determine whether a potent, reversible calpain inhibitor could reduce the cortical ischemic brain damage associated with focal ischemia in the rat. AK275 (Z-Leu-Abu-CONH-CH2CH3), the active isomer of the diastereomeric mixture, CX275, was employed in conjunction with a novel method of perfusing drug directly onto the infarcted cortical surface. This protocol reduced or eliminated numerous, nonspecific pharmacokinetic, hemodynamic, and other potentially confounding variables that might complicate interpretation of any drug effect. Focal ischemia was induced using a variation of the middle cerebral artery occlusion method. These studies demonstrated a reliable and robust neuroprotective effect of AK275 over the concentration range of 10 to 200 microM (perfused supracortically at 4 microliters/h for 21 h). Moreover, a 75% reduction in infarct volume was observed when initiation of drug treatment was delayed for 3 h postocclusion. Our data further support an important role of calpain in ischemia-induced neuropathology and suggest that calpain inhibitors may provide a unique and potentially powerful means of treating stroke and other ischemic brain incidents.