Age-related differences in the temporal and spatial regulation of matrix metalloproteinases (MMPs) in normal skin and acute cutaneous wounds of healthy humans

Despite the association of increasing age with chronic wound-healing disorders and an impaired rate of healing of acute cutaneous wounds, the role of matrix metalloproteinases (MMPs) is unknown. To determine the spatial and temporal patterns and activities of MMP-1, -2, -3 and -9, 132 healthy humans aged between 19 and 96 years underwent 4-mm punch biopsies followed by wound excision between day 1 and day 180 post-wounding. Wounds showed an age-related increase in MMP-2 and MMP-9 immunostaining from day 3; this was associated with degradation of gelatin as shown by zymograms and with increased proteinase activity as shown by azocoll assays. Distinct spatial localisations for each MMP were observed: MMP-2 was found in epidermal structures; MMP-9 was observed in inflammatory cells up to day 21; MMP-1 was localised to keratinocytes at the wound margin. Normal old skin showed pro-MMP-2 bands on zymography and increased MMP-2 immunostaining. These results indicate that: (1) intrinsic ageing is associated with the up-regulation of MMPs previously associated with chronic wound healing; (2) wound-tissue proteinases are essentially active up to day 21 postwounding; and (3) intrinsic ageing may predispose to tissue breakdown disorders because of MMP-2 up-regulation in normal skin.     

Octreotide in hyperinsulinism

In a limited number of case reports in infants, octreotide raised the blood glucose concentrations and decreased glucose requirements sufficiently to avoid pancreatectomy. This response occurs in the presence of frequent feedings and diazoxide therapy, and lasts from 1 month to greater than 5 years. As expected, octreotide reduces growth indices such as growth factors and growth rate in short-term assessment. However, an insufficient sample size, a lack of follow-up, and poor study design provide inconclusive data. Among the few case reports in adults with benign or malignant insulinoma, octreotide can significantly raise blood glucose concentrations. In long-term follow-up, octreotide has alleviated or reduced the frequency of hypoglycemic episodes for periods of 5 months to 2.5 years. Octreotide was administered subcutaneously in regimens of 100-1500 micrograms in three to four divided doses or as a continuous infusion. Continuous subcutaneous infusion may be attempted in patients intolerant to intermittent administration. Octreotide may worsen existing hypoglycemia as result of suppressing glucagon and growth hormone in the presence of unresponsive pancreatic hyperinsulinism. While the long-term effects of growth remain undetermined, current findings suggest octreotide may provide a reasonable addition or alternative to diazoxide in controlling symptoms of congenital hyperinsulinism. Octreotide may be useful in management of hypoglycemic symptoms in adult patients requiring medical treatment for insulinoma who are refractory or intolerant of diazoxide. Additional long-term studies are needed to address the cost effectiveness of octreotide therapy, identify patients most likely to respond, and determine the impact of octreotide on height.     

Gastric myoelectrical activity, gastric emptying and correlations with dyspepsia symptoms in patients with gastroesophageal reflux

BACKGROUND: Delayed gastric emptying is a mechanism that contributes to the pathogenesis of gastroesophageal reflux. Electrogastrogram changes, gastric emptying rates, and Helicobacter pylori status were investigated, and a correlation was sought with dyspepsia symptoms in gastroesophageal reflux disease patients. METHODS: Fifty patients (27 females; mean age 43) with gastroesophageal reflux were studied. Electrogastrographic recordings were obtained 30 minutes before and simultaneously with a 2-hour radionuclide gastric-emptying test using an isotope-labeled solid meal. Symptoms of nausea, abdominal bloating, abdominal pain, and early satiety were graded from 0 to 5. RESULTS: Thirty-six percent of patients had delayed gastric eliminating. Thirty-eight percent (19/50) patients had abnormal electrogastrograms, and 11 of these 19 also had delayed gastric emptying. There was a significant difference in the electrogastrographic parameter of postprandial power change in patients with delayed versus normal gastric emptying (0.20 +/- 0.8 dB vs 3.17 +/- 0.8 dB, p < 0.05). In patients with an abnormal electrogastrogram, the mean symptom score was significantly higher than in patients with a normal electrogastrogram (2.18 +/- 0.26 vs 1.35 +/- 0.16, p < 0.05). Twenty-one percent (7/33) of patients were positive (+) for Helicobacter pylori overall, but this did not seem to affect electrogastrogram and gastric emptying findings. CONCLUSIONS: Fifty-two percent of gastroesophageal reflux disease patients have gastric motor or myoelectrical abnormalities that contribute to the pathogenesis of this entity and also help explain the high prevalence of dyspepsia in the clinical presentation of gastroesophageal reflux disease.     

Immunohistochemical localization of somatostatin receptor SST2A in the rat pancreas

Somatostatin (SRIF) acts on specific membrane receptors to inhibit exocrine and endocrine pancreatic functions. Five SRIF receptor genes have been cloned, producing six receptor proteins (sst-s). We used a recently developed antibody to localize the sst2A splice variant in the rat pancreas. Western blots identified the sst2A receptor as an 90 kDa glycosylated protein in pancreatic tissue. In tyramide-amplified immunostainings all acinar cells, and the glucagon and pancreatic polypeptide immunoreactive cells (A and PP, respectively) were intensely labeled for sst2A, while no signal was detected in SRIF producing (D) cells. A very few insulin immunoreactive (B) cells were also labeled for sst2A, but the signal in these cells was lower than in exocrine, A or PP cells. Absorption of the sst2A antibody with the receptor peptide abolished specific staining in both immunoblots and tissue sections (negative control). These studies are the first to localize any SRIF receptor subtype in the rat pancreas. The specific localization of sst2A receptor in acinar, A and PP cells if confirmed in humans, would suggest that subtype specific analogs will be useful for the therapeutic regulation of exocrine and/or endocrine pancreatic secretion.     

Analysis of the interactions of SDZ PSC 833 ([3'-keto-Bmt1]-Val2]-Cyclosporine), a multidrug resistance modulator, with P-glycoprotein

Multidrug resistance (MDR) is considered to be an important impediment to the effective treatment of cancer. P-glycoprotein, the drug efflux pump that mediates this resistance, can be inhibited by a wide variety of pharmacological agents, resulting in the circumvention of the MDR phenotype. SDZ PSC 833 ([3'-keto-Bmt1]-Val2]-cyclosporine), a nonimmunosuppressive cyclosporine D derivative, was identified to be a potent MDR modulator (Gaveriaux et al. J. Cell Pharmacol. 2:225-234; 1991). In this study, the interactions of P-glycoprotein with two cyclosporine derivatives, SDZ PSC 833 and cyclosporine A (CsA, Sandimmune), were analyzed. SDZ PSC 833 enhanced the sensitivity of the MDR cells to anticancer drugs by increasing the accumulation and inhibiting the efflux of cytotoxic agents from resistant cells more efficiently than CsA. The two cyclosporine analogs competed with the labeling of P-glycoprotein by a photoactive cyclosporine derivative. In addition, membrane vesicles derived from resistant cells bound SDZ PSC 833. However, CsA was transported by P-glycoprotein, whereas SDZ PSC 833 was not actively transported. This resulted in a prolonged inhibitory effect by SDZ PSC 833. The studies suggest that the binding of SDZ PSC 833 to P-glycoprotein in the absence of its transport from MDR cells mediated its high potency as an MDR reversing agent. In addition, the comparison of the two cyclosporine analogs indicated that limited chemical modifications of MDR reversing agents can affect their potential to inhibit P-glycoprotein function.     

Separation of gating properties from permeation and block in mslo large conductance Ca-activated K+ channels

In this and the following paper we have examined the kinetic and steady-state properties of macroscopic mslo Ca-activated K+ currents in order to interpret these currents in terms of the gating behavior of the mslo channel. To do so, however, it was necessary to first find conditions by which we could separate the effects that changes in Ca2+ concentration or membrane voltage have on channel permeation from the effects these stimuli have on channel gating. In this study we investigate three phenomena which are unrelated to gating but are manifest in macroscopic current records: a saturation of single channel current at high voltage, a rapid voltage-dependent Ca2+ block, and a slow voltage-dependent Ba2+ block. Where possible methods are described by which these phenomena can be separated from the effects that changes in Ca2+ concentration and membrane voltage have on channel gating. Where this is not possible, some assessment of the impact these effects have on gating parameters determined from macroscopic current measurements is provided. We have also found that without considering the effects of Ca2+ and voltage on channel permeation and block, macroscopic current measurements suggest that mslo channels do not reach the same maximum open probability at all Ca2+ concentrations. Taking into account permeation and blocking effects, however, we find that this is not the case. The maximum open probability of the mslo channel is the same or very similar over a Ca2+ concentration range spanning three orders of magnitude indicating that over this range the internal Ca2+ concentration does not limit the ability of the channel to be activated by voltage.     

Systematic screening of the LDL-PLA2 gene for polymorphic variants and case-control analysis in schizophrenia

Systematic scans of the genome using microsatellite markers have identified chromosome 6p21.1 as a putative locus for schizophrenia in multiply affected families. There is also evidence from a series of studies for a role of abnormal phospholipid metabolism in schizophrenia. In light of these findings, and the role of platelet activating factor in neurotransmission and neurodevelopment, we have examined the LDL-PLA2 (plasma PAF acetylhydrolase, PAF-AH) gene, a serine dependent phospholipase that has been mapped by hybrid mapping to chromosome 6p21.1, as a positional candidate gene for schizophrenia. The gene was systematically screened using SSCP/HD analysis for polymorphisms associated with the disease. Four polymorphic variants were found within the gene and studied in a group of 200 schizophrenic patients and 100 controls. The variant in exon 7 (Iso195Thr) was found to be weakly associated with schizophrenia (p = 0.04) and the variant in exon 11 (Val379Ala) almost reached significance (p = 0.057). After correcting for multiple testing no significant associations were detected. Haplotype analysis combining pairs of polymorphisms also provided no evidence for association of this gene with schizophrenia in our sample of patients.