Intestinal alkaline phosphatase at the crossroad of intestinal health and disease - a putative role in type 1 diabetes.

BACKGROUND: Patients with type 1 diabetes have shown an increase in circulating cytokines, altered lipoprotein metabolism and signs of vascular dysfunction in response to high-fat meals. Intestinal alkaline phosphatase (IAP) regulates lipid transport and inflammatory responses in the gastrointestinal tract. We therefore hypothesized that changes in IAP activity could have profound effects on gut metabolic homeostasis in patients with type 1 diabetes. METHODS: Faecal samples of 41 nondiabetic controls and 46 patients with type 1 diabetes were analysed for IAP activity, calprotectin, immunoglobulins and short-chain fatty acids (SCFAs). The impact of oral IAP supplementation on intestinal immunoglobulin levels was evaluated in C57BL/6 mice exposed to high-fat diet for 11 weeks. RESULTS: Patients with type 1 diabetes exhibited signs of intestinal inflammation. Compared to controls, patients with diabetes had higher faecal calprotectin levels, lower faecal IAP activities accompanied by lower propionate and butyrate concentrations. Moreover, the amount of faecal IgA and the level of antibodies binding to oxidized LDL were decreased in patients with type 1 diabetes. In mice, oral IAP supplementation increased intestinal IgA levels markedly. CONCLUSION: Deprivation of protective intestinal factors may increase the risk of inflammation in the gut - a phenomenon that seems to be present already in patients with uncomplicated type 1 diabetes. Low levels of intestinal IgA and antibodies to oxidized lipid epitopes may predispose such patients to inflammation-driven complications such as cardiovascular disease and diabetic nephropathy. Importantly, oral IAP supplementation could have beneficial therapeutic effects on gut metabolic homeostasis, possibly through stimulation of intestinal IgA secretion.

Prevention of antibiotic-associated metabolic syndrome in mice by intestinal alkaline phosphatase.

AIMS: To examine whether co-administration of intestinal alkaline phosphatase (IAP) with antibiotics early in life may have a preventive role against metabolic syndrome (MetS) in mice. METHODS: A total of 50 mice were allocated to four treatment groups after weaning. Mice were treated with azithromycin (AZT) ± IAP, or with no AZT ± IAP, for three intermittent 7-day cycles. After the last treatment course, the mice were administered a regular chow diet for 5 weeks and subsequently a high-fat diet for 5 weeks. Body weight, food intake, water intake, serum lipids, glucose levels and liver lipids were compared. 16S rRNA gene pyrosequencing was used to determine the differences in microbiome composition. RESULTS: Exposure to AZT early in life rendered mice susceptible to MetS in adulthood. Co-administration of IAP with AZT completely prevented this susceptibility by decreasing total body weight, serum lipids, glucose levels and liver lipids to the levels of control mice. These effects of IAP probably occur as a result of changes in the composition of specific bacterial taxa at the genus and species levels (e.g. members of Anaeroplasma and Parabacteroides). CONCLUSIONS: Co-administration of IAP with AZT early in life prevents mice from susceptibility to the later development of MetS. This effect is associated with alterations in the composition of the gut microbiota. IAP may represent a novel treatment against MetS in humans.

Intestinal alkaline phosphatase preserves the normal homeostasis of gut microbiota.

BACKGROUND AND AIMS: The intestinal microbiota plays a critical role in maintaining human health; however, the mechanisms governing the normal homeostatic number and composition of these microbes are largely unknown. Previously it was shown that intestinal alkaline phosphatase (IAP), a small intestinal brush border enzyme, functions as a gut mucosal defence factor limiting the translocation of gut bacteria to mesenteric lymph nodes. In this study the role of IAP in the preservation of the normal homeostasis of the gut microbiota was investigated. METHODS: Bacterial culture was performed in aerobic and anaerobic conditions to quantify the number of bacteria in the stools of wild-type (WT) and IAP knockout (IAP-KO) C57BL/6 mice. Terminal restriction fragment length polymorphism, phylogenetic analyses and quantitative real-time PCR of subphylum-specific bacterial 16S rRNA genes were used to determine the compositional profiles of microbiotas. Oral supplementation of calf IAP (cIAP) was used to determine its effects on the recovery of commensal gut microbiota after antibiotic treatment and also on the colonisation of pathogenic bacteria. RESULTS: IAP-KO mice had dramatically fewer and also different types of aerobic and anaerobic microbes in their stools compared with WT mice. Oral supplementation of IAP favoured the growth of commensal bacteria, enhanced restoration of gut microbiota lost due to antibiotic treatment and inhibited the growth of a pathogenic bacterium (Salmonella typhimurium). CONCLUSIONS: IAP is involved in the maintenance of normal gut microbial homeostasis and may have therapeutic potential against dysbiosis and pathogenic infections.

Identification of a thyroid hormone receptor that is pituitary-specific.

Three cellular homologs of the v-erbA oncogene were previously identified in the rat; two of them encode high affinity receptors for the thyroid hormone triiodothyronine (T3). A rat complementary DNA clone encoding a T3 receptor form of the ErbA protein, called r-ErbA beta-2, was isolated. The r-ErbA beta-2 protein differs at its amino terminus from the previously described rat protein encoded by c-erbA beta and referred to as r-ErbA beta-1. Unlike the other members of the c-erbA proto-oncogene family, which have a wide tissue distribution, r-erbA beta-2 appears to be expressed only in the anterior pituitary gland. In addition, thyroid hormone downregulates r-erbA beta-2 messenger RNA but not r-erbA beta-1 messenger RNA in a pituitary tumor-derived cell line. The presence of a pituitary-specific form of the thyroid hormone receptor that may be selectively regulated by thyroid hormone could be important for the differential regulation of gene expression by T3 in the pituitary gland.

Histone acetylation and cancer.

In the past year, several papers have been published which implicate a link between alterations in chromatin structure and the development of cancer. Both histone hyperacetylation and hypoacetylation appear to be important in the neoplastic process, depending on the target gene involved. In the case of colon cancer, induction of the p21 gene by histone hyperacetylation may be a mechanism by which dietary fiber prevents carcinogenesis.

Differential and tissue-specific regulation of the multiple rat c-erbA messenger RNA species by thyroid hormone.

Thyroid hormone (T3) has been shown to regulate the level of its receptor in a number of tissues and cell lines. Recently, proteins encoded by the protooncogene c-erbA have been identified as T3 receptors. In the rat, four c-erbA gene products have been isolated, three of which, r-erbA alpha-1, r-erbA beta-1, and r-erbA beta-2, encode biologically active T3 receptors; the fourth, r-erbA alpha-2, may play an inhibitory role in T3 action. The present work examines the molecular nature of T3 receptor autoregulation using probes specific for each c-erbA mRNA. Rats were rendered hypothyroid with propylthiouracil and then treated with either saline or T3. Northern blot analyses reveal marked tissue-specific and differential regulation of the multiple c-erbA mRNAs by T3. In the pituitary the levels of r-erbA beta-1 mRNA increase, whereas the levels of the pituitary-specific r-erbA beta-2 mRNA decrease with T3 treatment. In heart, kidney, liver, and brain the levels of r-erbA beta-1 are unaffected by thyroidal status. The levels of both r-erbA alpha mRNAs decrease with T3 treatment in all tissues examined except for the brain, where there is no change. In addition, we find that changes in the mRNAs encoding specific subpopulations of T3 receptors do not always parallel changes in total nuclear T3 binding. Differential regulation of the specific c-erbA mRNA species could have important consequences for T3 action.

Na-K-2Cl cotransporter gene expression and function during enterocyte differentiation. Modulation of Cl- secretory capacity by butyrate.

The basolateral Na-K-2Cl cotransporter (NKCC1) is a key component of the intestinal crypt cell secretory apparatus. Its fate during the transition to absorptive enterocyte and the potential impact of its altered expression on secretory output have not been addressed. In this report, NKCC1 mRNA was found to be expressed in rat jejunal crypt but not villus cells. Butyrate treatment of intestinal epithelial HT29 cells induced a differentiation pattern that recapitulated the rat intestinal crypt-villus axis, with NKCC1 mRNA levels decreasing in a time- and dose-dependent fashion in parallel with upregulation of apical brush-border markers. Butyrate but not acetate or proprionate decreased basal and cAMP-stimulated bumetanide-sensitive K+ (86Rb) uptake in both HT29 cells and the Cl--secreting T84 line. Butyrate markedly decreased transepithelial Cl- secretion in confluent T84 monolayers without effect on cAMP-regulated apical Cl- efflux. We conclude that NKCC1 regulation during enterocyte differentiation occurs at the level of gene expression, and that selective downregulation of NKCC1 gene expression and function by butyrate leads to a profound decrease in transepithelial Cl- secretion. These data emphasize the importance of NKCC1 in determining epithelial secretory capacity and suggest the possibility of modulation of the enterocytic transport phenotype as therapy for diarrheal disorders.

A novel member of the thyroid/steroid hormone receptor family is encoded by the opposite strand of the rat c-erbA alpha transcriptional unit.

A cDNA encoding a novel member of the thyroid/steroid hormone receptor superfamily, called Rev-ErbA alpha, has been isolated from a rat GH3 cell library. Rev-ErbA alpha is an approximately 56-kilodalton protein most similar in structure to the thyroid hormone receptor (c-erbA) and the retinoic acid receptor, but it does not bind either thyroid hormone or retinoic acid. The mRNA encoding Rev-ErbA alpha is present in many tissues and is particularly abundant in skeletal muscle and brown fat. A genomic DNA fragment containing the entire Rev-ErbA alpha cDNA sequence was isolated and characterized. Remarkably, this DNA fragment also contained a portion of the c-erbA alpha gene. r-erbA alpha-1 and r-erbA alpha-2 are alternative splice products of the c-erbA alpha gene and are members of the receptor superfamily. The genes encoding Rev-ErbA alpha and r-erbA alpha-2 overlap, with their coding strands oriented opposite one another. A 269-base-pair segment of the bidirectionally transcribed region is exonic in both the Rev-ErbA alpha and r-erbA alpha-2 genes, resulting in complementary mRNAs. Thus, through alternative splicing and opposite-strand transcription, a single genomic locus codes for three different members of the thyroid/steroid hormone receptor superfamily. Potential implications of this unusual genomic arrangement are discussed.

Identification of a rat c-erbA alpha-related protein which binds deoxyribonucleic acid but does not bind thyroid hormone.

c-erbA cDNAs encoding thyroid hormone-binding receptor proteins have been previously isolated from several species and tissues. We have isolated a novel rat c-erbA cDNA, r-erbA alpha-2, identical to the rat brain c-erbA alpha cDNA (which we refer to as r-erbA alpha-1) except at the 3'-end of the cDNA, which encodes an altered carboxy-terminal region of the predicted amino acid sequence. The r-erbA alpha-2 cDNA is most closely related to the human testicular c-erbA alpha cDNA. The apparent molecular weight of the in vitro protein product of this cDNA is 55 K, close to that predicted from the nucleotide sequence. The r-erbA alpha-2 protein binds a DNA fragment containing a putative T3-responsive sequence from the rat GH gene. However, the r-erbA alpha-2 protein product does not bind T3. RNA isolated from rat GH3 cells and various rat tissues contains at least three mRNAs hybridizing to c-erbA alpha probes. A predominant 2.6 kilobase mRNA hybridizes specifically to r-erbA alpha-2, while a 5.0 kb mRNA hybridizes to r-erbA alpha-1-specific cDNA probes. The r-erbA alpha-1-related 5.0 kb mRNA is down-regulated by T3 treatment in GH3 cells as has previously been described for the 2.6 kb mRNA. The r-erbA alpha-2 mRNA is most abundant in brain, whereas the r-erbA alpha-1 mRNA is found in highest concentration in brown fat and skeletal muscle. r-erbA alpha-1 mRNA, unlike r-erbA alpha-2 mRNA, is undetectable in testis. Southern analyses suggest that the r-erbA alpha-1 and r-erbA alpha-2 mRNAs are derived from a single gene transcript.

Thyroid hormone responsiveness is developmentally regulated in the rat small intestine: a possible role for the alpha-2 receptor variant.

Thyroid hormone (T3) alters gene expression through binding to a receptor protein located within the nucleus of target cells. Multiple forms of the T3 receptor (TR) have been identified and are encoded by the alpha and beta c-erbA genes. We have previously found that TR beta-1 is the major receptor form expressed in the adult rat small intestine, although there are also moderate levels of c-erbA alpha-2, a nonhormone-binding variant that is thought to inhibit T3 action. In developing rats, we studied the regulation of two small intestinal enterocyte genes previously shown to be T3 responsive, lactase and 3.0-kilobase intestinal alkaline phosphatase (IAP). Animals were treated with six daily ip injections of either saline (control) or 30 micrograms/100 g BW T3 (T3 group) and killed at 10 and 25 days of age. Northern analyses of RNA derived from intestinal tissues showed that the magnitude of the T3-induced changes in lactase and IAP gene expression increased with development. Jejunal 3.0-kilobase IAP messenger RNA (mRNA) levels were unaffected by T3 at 10 days, but increased by 15-fold at 25 days. Similarly, jejunal lactase mRNA levels were unchanged by T3 at 10 days, but decreased by 75% at 25 days. Qualitatively similar results were seen in the duodenum and ileum. Studies of TR expression revealed that TR beta-1 mRNA levels were unchanged during the developmental period, whereas the levels of c-erbA alpha-2 decreased by 90% between 5-25 days after birth. These results indicate that the rat small intestine becomes increasingly T3 responsive during postnatal development. These changes occur in parallel with a decline in c-erbA alpha-2 levels, suggesting that this T3 receptor variant may play a role in this hormonal responsiveness.

Outpatient thyroid and parathyroid surgery: a prospective study of feasibility, safety, and costs.

BACKGROUND: The purpose of this study was to determine feasibility, safety, and cost savings of outpatient thyroid and parathyroid surgery. METHODS: Consecutive unselected patients undergoing thyroid and parathyroid operations by two surgeons with a special interest in endocrine surgery were studied prospectively. RESULTS: One-hundred patients underwent operation, 61 as outpatients and 39 as inpatients. Outpatients included those undergoing thyroid lobectomy (39), total thyroidectomy (10), total thyroidectomy with parathyroidectomy (1), total thyroidectomy with modified neck dissection (1), and parathyroidectomy (10). Inpatients included those undergoing thyroid lobectomy (15), total thyroidectomy (8), total thyroidectomy with neck dissection (4), removal of substernal goiter (2), and parathyroidectomy (10). The average age of inpatients was slightly higher than that of outpatients (p < 0.05). Average hospital cost for outpatients was $1991 +/- $279 (range, $1594 to $2783) and for inpatients it was $2875 +/- 615 (range, $2031 to $4216), p < 0.001. Reasons for admission included extent of surgery (6), nausea (5), oversedation (4), urinary retention (2), inadequate home help (6), long travel time (2), patient preference (9), and medical reasons (5). No outpatients subsequently required admission. CONCLUSIONS: Outpatient thyroid and parathyroid surgery can be feasible and safe and resulted in a 30% savings in hospital costs. After extensive operations patients continue to require admission for postanesthetic complications, social reasons, or presence of serious comorbid disease.

Bombesin maintains enterocyte phenotype in fasted rats.

BACKGROUND: Previous studies have suggested a relationship between enterocyte phenotype and the growth state of the epithelium; under atrophic conditions, lactase gene expression is high, whereas intestinal alkaline phosphatase (IAP) expression is low, and vice versa. On the basis of this model, we hypothesized that the intestinal trophic factor bombesin would alter brush-border enzyme gene expression in a predictable way. METHODS: Adult rats were fasted for 48 hours and treated (intraperitoneally) with either 10 micrograms/kg bombesin or the saline control every 8 hours. Small intestinal mucosal scrapings were taken, total RNA purified, and Northern blot analyses performed with radiolabeled cDNA probes corresponding to lactase, IAP, villin, and actin. Tissue samples were also taken for measurement of mucosal thickness. RESULTS: Bombesin administration caused an increase in jejunal mucosal thickness, thereby confirming its trophic effects. Bombesin resulted in a decrease in lactase mRNA levels and an increase in IAP mRNA levels along the length of the small intestine. No changes occurred in the expression of either villin or actin. The pattern of enterocyte gene expression in the bombesin-treated animals was similar to that in control-fed rats. CONCLUSIONS: Bombesin differentially regulates rat enterocyte gene expression, decreasing lactase and increasing IAP mRNA levels. These results lend further support to the hypothesis that a close relationship exists between enterocyte phenotype and epithelial growth state.

Small bowel adaptation: counterregulatory effects of epidermal growth factor and somatostatin on the program of early gene expression.

BACKGROUND: Small intestinal crypt cell proliferation is essential to the normal renewal of the epithelium, as well as the adaptive responses that follow resection or injury. The present studies were designed to elucidate the molecular mechanisms by which epidermal growth factor (EGF) and somatostatin interact to regulate crypt cell proliferation. METHODS: Rat crypt (IEC-6) cells were maintained in Dulbecco's modified Eagle's medium plus 10% fetal calf serum and treated with EGF (10 or 100 ng/ml) or somatostatin (0.5 microgram/ml). Cell counts were done to examine the effects on cellular growth, and Northern blot analyses were carried out by using complementary DNA probes corresponding to various protooncogenes. RESULTS: EGF caused a 41% increase in cellular growth, an effect that was almost completely blocked by pretreatment (30 minutes) with somatostatin. EGF led to dramatic increases in c-fos (greater than 20-fold), c-jun (2-fold), and jun B (3-fold) gene expression at 30 minutes, consistent with the previously characterized immediate-early gene response in IEC-6 cells. Somatostatin alone had no effects on protooncogene levels, but pretreatment with somatostatin resulted in a marked inhibition (80%, p < 0.001 in all cases) of the EGF-induced increases in protooncogene expression. CONCLUSIONS: Somatostatin inhibits the EGF-induced protooncogene expression in IEC-6 cells. The somatostatin inhibition of immediate-early gene expression lends support to its role as a negative growth regulator in intestinal epithelia and indicates that its effect occur at an upstream site in the cellular growth response.

Is sestamibi-guided parathyroidectomy really cost-effective?

BACKGROUND: Sestamibi-guided limited neck explorations are an alternative to the standard bilateral neck exploration for patients with primary hyperparathyroidism. A recently published meta-analysis by Denham and Norman (JACS vol.186, 1998) suggested that a sestamibi-directed approach offers a cost benefit because it decreases operative and recovery room times, hospital stay, and the number of frozen sections needed. METHODS: We reviewed 41 bilateral neck explorations for primary hyperparathyroidism and compared our results with those reported by the meta-analysis to determine whether a sestamibi-directed approach is cost effective. RESULTS: Operative and recovery room times averaged 60.3 +/- 19.3 and 45 minutes, respectively. Forty six percent of the patients were treated as outpatients, and 1.21 +/- 0.57 frozen sections were obtained per case. Our standard bilateral exploration cost 47% less than the bilateral approach and 17% less than the sestamibi-directed operation calculated in the meta-analysis. There were no cases of nerve injury or permanent hypocalcemia, 98% of patients were cured, and 61% of patients did not require narcotics postoperatively. CONCLUSIONS: Sestamibi-guided parathyroidectomy may not offer any advantage over the standard bilateral exploration. In our experience, a bilateral neck exploration can be performed on an outpatient basis and at low cost, with a high success rate and minimal morbidity. Most patients do not require narcotics, and the cosmetic results are excellent.

Thyroid hormone and the gut: selective transcriptional activation of a villus-enterocyte marker.

BACKGROUND: Thyroid hormone (T3) is an important regulator of gut mucosal growth, differentiation, and barrier function, but its mechanism of action in the gastrointestinal tract is largely unknown. The present studies were carried out to define the molecular mechanisms by which T3 alters gut gene expression. METHODS: In vivo: Adult, male, Sprague-Dawley rats were given three daily injections (intraperitoneal) of either saline solution or 30 micrograms/kg triiodothyronine. Small intestinal tissues were harvested, and Northern blot analyses were performed by using specific radiolabeled cDNA probes. In vitro: HT-29 cells were transfected with reporter plasmids and treated with or without T3, and chloramphenicol acetyltransferase activity was measured. RESULTS: The T3-induced changes in enterocyte gene expression occurred in villus enterocytes and not in crypt cells and were independent of food intake. Northern analyses with an intron-specific probe revealed that the T3 induction in intestinal alkaline phosphatase (IAP) expression occurs at the level of transcription. Transient transfection assays revealed no T3-induced changes under basal conditions but marked increases (sixfold, p < 0.001) when a T3-receptor (TR beta-1) plasmid was cotransfected. Furthermore, T3 was found to induce greater IAP reporter gene activity in differentiated (+ sodium butyrate) compared with undifferentiated HT-29 cells. CONCLUSIONS: T3 induces IAP expression at the level of gene transcription. Both in vivo and in vitro, IAP transcriptional activation occurs to a greater extent in differentiated enterocytes than in undifferentiated crypt cells. Transactivation of the IAP gene by T3 is mediated via a DNA cis-element(s) located within the 2.4 kb segment present in the reporter gene.

Short-chain fatty acids and thyroid hormone interact in regulating enterocyte gene transcription.

BACKGROUND: Enterocyte differentiation is known to be regulated by a variety of extracellular compounds, among which are triiodothyronine (T3) and the short-chain fatty acids (SCFAs). Because several SCFAs are known to induce histone hyperacetylation, and T3 action has been recently linked to chromatin structure, we sought to investigate the interplay between SCFAs and T3 in regard to the enterocyte differentiation marker, intestinal alkaline phosphatase (IAP). METHODS: Caco-2 cells were transiently transfected with a reporter construct containing 2.4 kb of the human IAP gene 5' flanking region (IAP2.4CAT). Cotransfections were carried out with and without thyroid hormone receptor-1 (TR beta-1) or histone deacetylase-1 (HDAC-1) expression plasmids. Cells were treated with 5 mmol/L SCFAs (propionic, butyric, valeric, or caproic acids as propionate, butyrate, valerate, or caproate, respectively), with and without 10 nmol/L T3. Reporter gene activity was measured and the level of histone acetylation assessed by means of acid-urea-triton (AUT) gel assays. RESULTS: TR beta-1 cotransfection caused a marked decrease in IAP reporter gene activity, which is consistent with the well-known phenomenon of ligand independent repression (LIR), whereas T3 treatment reversed the LIR and caused further reporter gene activation. Treatment with SCFAs similarly resulted in a complete blockage of LIR, and, in fact, turned the TR beta-1 into a transcriptional activator, even in the absence of T3. Concomitant treatment with T3 and butyric acid produced an additive effect on IAP transactivation. In contrast, cotransfection with HDAC-1 attenuated the effects of SCFAs on IAP gene activation. AUT gel studies demonstrated histone hyperacetylation in response to SCFA treatment. CONCLUSION: One or more DNA cis-elements in the human IAP gene mediate ligand independent repression by the TR beta-1, an effect that can be entirely reversed by those SCFAs that induce histone hyperacetylation. In addition T3 and SCFAs can act in concert to induce IAP gene transcription, demonstrating an important link between triiodothyronine and histone hyperacetylation in regard to enterocyte-specific gene expression.

Fine-needle aspiration of normal thyroid tissue may result in the misdiagnosis of microfollicular lesions.

BACKGROUND: Inadvertent sampling of normal thyroid tissue surrounding a nodule may occur when clinically inexperienced personnel perform fine-needle aspiration (FNA) or when a nodule is small. Because the cytologic characteristics of normal thyroid tissue are not well known, we prospectively studied 42 patients undergoing thyroidectomy. METHODS: FNA was performed from the grossly normal contralateral lobe during thyroidectomy. Cytopathologists examined the slides without knowing the source of the tissue. RESULTS: FNA of grossly normal thyroid tissue was adequate for interpretation in 32 of 42 patients, and in nine of 42 cases it was interpreted as unremarkable. However, the remaining specimens were classified as microfollicular lesions (18), mixed macromicrofollicular lesions (three), Hürthle cell lesion (one), and papillary thyroid carcinoma (one). CONCLUSIONS: FNA of grossly normal thyroid tissue suggested a microfollicular lesion in 18 (56%) patients, a result that would raise the possibility of a follicular carcinoma and often lead to the recommendation for operation. When FNA is performed, normal thyroid tissue surrounding a nodule should be avoided, and the possibility of a sampling error should be considered when a microfollicular pattern is obtained in a patient with a small nodule.

Seizure-associated pulmonary edema and cerebral oxygenation in the rat.

Cerebral partial pressure of O2 (PO2), relative changes in the ratio of reduced/oxidized cytochrome aa3, blood flow, and the arteriovenous difference in O2 content were measured during seizures with and without pulmonary edema. Seizures were induced with bicuculline (0.2-1.2 mg/kg iv) in rats anesthetized with 70% N2O and paralyzed with curare. Briefer seizures were accompanied by increased cerebral PO2 and increased oxidation of cytochrome aa3. Lung water content and arterial O2 partial pressure (PaO2) remained normal. Longer duration seizures were also accompanied initially by increases in cerebral oxygenation. Within minutes, however, PaO2 fell from a mean of 118 to 51 mmHg, and lung water content increased from 76.2 to 83.6%. Cerebral PO2 fell but most often rose back to or above control levels, while cytochrome aa3 became markedly reduced. Simultaneously, cerebral blood flow increased more than 300% above preseizure values and O2 delivery increased more than O2 consumption. The reductive shift of cytochrome aa3 was greater than that produced by lowering PaO2 to equivalent values in seizure-free rats. The reductive shift of cytochrome aa3, despite increased O2 delivery, may be indicative of derangements in cerebral O2 diffusion or energy metabolism.

Videoscopic harvest of the inferior epigastric artery.

The inferior epigastric artery has been found to be a useful conduit for performing arterial coronary revascularization. The present report describes a minimally invasive port access technique for harvesting the inferior epigastric artery.

Role of pulmonary edema in phasic changes of cerebral oxygenation during serial seizures.

To examine whether pulmonary dysfunction leads to episodes of cerebral hypoxia during recurrent seizures, measurements were made of arterial blood pressure, blood-gases, cerebral pO2, and relative changes in cytochrome a,a3 redox levels in anesthetized, paralyzed rats. Seizures were induced serially with bicuculline (BIC) or pentylenetetrazol (PTZ). During early seizures, cerebral oxygenation increased phasically. As seizures continued, a transition often occurred following which seizures were accompanied by phasic decreases in cerebral oxygenation. In addition, pulmonary edema often occurred at an unpredictable point during a series of seizures. Seizure-associated pulmonary edema was less likely to occur with pentobarbital anesthesia and PTZ seizures, than with nitrous oxide anesthesia and BIC seizures. Pulmonary edema was always accompanied by prolonged increases in blood pressure and paroxysmal electrocortical activity, and by hypoxemia, acidemia, and decreased cerebral oxygen supply. Despite the severity of these physiological changes, the transition from phasic increases to decreases in cerebral oxygenation during serial seizures occurred with virtually the same frequency in rats with and without pulmonary edema. This indicates that this transition is independent of pulmonary edema.