Evidence for involvement of cyclic nucleotides in intrinsic factor secretion by isolated rabbit gastric mucosa.

Secretion of intrinsic factor (IF) has previously been demonstrated in isolated rabbit fundic mucosa maintained in organ culture. We have now investigated the possibility that cyclic nucleotides may play a role in IF secretion. A phosphodiesterase inhibitor, 3-isobutyl methylxanthine (IBMX), stimulated IF secretion nearly fourfold while increasing tissue levels of both cyclic AMP (cAMP) and cyclic GMP (cGMP). Peak IF secretion in response to IBMX was not reached until after tissue cAMP levels were maximal. Dibutyryl cAMP and 8-Br-cAMP increased secretion by the same order of magnitude as did IBMX, whereas corresponding analogues of cGMP had no such effect. Histamine increased secretion of IF. In the presence of 40 microM IBMX, histamine elevated tissue levels of cAMP, but not of cGMP, and the stimulating effect of 10 microM histamine on IF secretion was potentiated. An H2 receptor antagonist, cimetidine, blocked the increases in IF secretion and tissue cAMP levels due to histamine, and the increase in IF secretion due to IBMX. These observations are consistent with a role for cAMP in the secretion of IF by isolated gastric mucosa.

Intrinsic factor-mediated absorption of cobalamin by guinea pig ileal cells.

To investigate the fate of intrinsic factor and cobalamin during cobalamin absorption, we incubated enterocytes isolated from guinea pig ileum for periods of up to 30 min with (57)Co-labeled cyano-cobalamin bound either to human intrinsic factor or to rabbit intrinsic factor biosynthetically labeled with [(35)S]methionine. When the labeled complex was incubated for 30 min with isolated ileal cells under conditions that block cellular metabolism, virtually all cellular radioactivity could be removed by washing the cell surface with EDTA or acid. In contrast, washing removed only half the radioactivity from cells incubated at 37 degrees C in O(2). When residual cellular radioactivity was extracted and analyzed by gel filtration, 80-94% of both the (35)S and (57)Co radioactivity eluted in the same fractions as the original complex. The remaining 6-20% eluted as free [(57)Co]cobalamin or [(35)S]methionine. To examine events occurring after 30 min, we instilled into tied-off ileal loops of intact guinea pigs radiolabeled intrinsic factor-cobalamin complex and extracted nondissociable radioactivity 2-4.5 h later. The proportion of extracted (57)Co eluting as free cobalamin increased to 39-46%, that eluting as intrinsic factor-cobalamin complex declined to 22-45%, and 9-34% now eluted as a macromolecule that reacted with antitranscobalamin II antibody but not antiintrinsic factor antibody. Extracted (35)S radioactivity eluted in several peaks in addition to the intrinsic factor peak. These findings suggest that (a) after reversible attachment of intrinsic factor-cobalamin complex to its ileal surface receptor, an energy-dependent process prevents removal of the complex from the cell surface by EDTA or acid; (b) cobalamin dissociates from intrinsic factor and, as suggested by previous workers, binds to a molecule antigenically similar to transcobalamin II; and (c) intrinsic factor is slowly degraded and forms breakdown products that are detectable in ileal extracts.

Pancreatic carcinoma: report of two cases presenting with unusual metastases.

We report two patients with adenocarcinoma of the body and tail of the pancreas who presented with features localized to the metastatic sites. A 67-year-old gentleman presented with right groin mass due to spermatic cord metastasis and later developed duodenal obstruction; the other gentleman was 69 years old and presented with change of bowel habit as a result of pelvic/pararectal metastasis.

Maintenance of skeletal muscle intracellular glutamine during standard surgical trauma.

Skeletal muscle glutamine (GLN) concentration falls following injury and infection. In an attempt to prevent this decline and to characterize its influence on the efflux of amino acid (AA) from skeletal muscle, we administered varying quantities of AA (0,2, and 4 g/kg X day) as saline or AA solutions with or without GLN enrichment to 22 postoperative dogs. Plasma and muscle AA were determined before and 24 hr after standard laparotomy. Hindquarter AA efflux was measured at 6 and 24 hr. Skeletal muscle nitrogen declined in saline controls (69.8 +/- 8.5 vs 52.8 +/- 8.4 mmol/liter; p less than 0.01), largely due to the fall in intracellular GLN (21.48 +/- 3.21 vs 15.86 +/- 3.80; p less than 0.05). Similar alterations were seen in the animals receiving 2 g/kg. However, both intracellular nitrogen and GLN were maintained in animals receiving 4 g/kg, whether the AA solutions contained GLN or not (skeletal muscle nitrogen before 64.3 +/- 8.6 mmol/l vs 65.4 +/- 7.0 after, GLN 19.2 +/- 3.4 vs 19.9 +/- 3.0). Hindquarter AA efflux was reduced in those animals at 6 hr compared with saline-treated animals (-6.52 +/- 1.8 and -7.70 +/- 5.90 vs -19.05 +/- 4.06 mumol/kg X min; p less than 0.05). Intracellular GLN can be maintained during operative stress with adequate nitrogen infusion. Replacing 50% of the balanced AA solution with GLN resulted in equally effective maintenance of intracellular GLN levels and a comparable reduction in skeletal muscle AA efflux. Preservation of normal intracellular GLN levels with adequate AA nutrition may be essential for the conservation of muscle protein.

Large bowel ischemia following laparoscopic inguinal hernioplasty.

The adverse physiological effects of pneumoperitoneum are well understood. However, the clinical implications of compromised mesenteric circulation through several mechanical and physiological mechanisms are not as well recognized. We describe a fatal case of large bowel ischemia following an elective laparoscopic transperitoneal inguinal hernioplasty. The patient was a 78-year-old man who died within 30 h after an uneventful anesthesia and laparoscopic surgery. An autopsy revealed thrombosis of the inferior mesenteric artery and an infrarenal aortic aneurysm with thrombotic plaque on its wall. We reviewed the relevant literature on laparoscopic procedures and mesenteric ischemia. To our knowledge, this is the first reported case of large bowel ischemia following pneumoperitoneum. We conclude that the presence of an aortic aneurysm is an added risk factor in laparoscopy.

"The stones...to rise".

Late complications of laparoscopic cholecystectomy are less addressed. Spillage of stone during laparoscopic cholecystectomy is a recognized complication. However, late sequelae of spillage of stones are less clear. We report a case of late and recurrent subphrenic abscess following laparoscopic cholecystectomy. This was a 65-year-old gentleman who underwent laparoscopic cholecystectomy in 1991. He presented 3 years and even 10 years after the operation with subphrenic abscess. Interesting CT scan findings are described. Surgical open drainage is recommended as opposed to percutaneous drainage. Emphasis is given to take precautions to avoid spillage of stones. We feel that this is the first case of a complication of laparoscopic cholecystectomy presenting so late and as a recurrent problem.

Laparoscopic transperitoneal adrenalectomy.

BACKGROUND: From November 1993 to May 2002 a total of 172 laparoscopic adrenalectomies were attempted in 152 patients in centers throughout the United Kingdom. RESULTS: The median age was 52 years (18-77 years). Sixty-three percent were female. Indications for resection were Conn's syndrome (60), pheochromocytoma (35), Cushing's disease (24), Cushing's adenoma (8), cortisol-secreting carcinoma (1), other secreting tumor (2), nonfunctioning adenoma (17), congenital adrenal hyperplasia (4), metastatic disease (7), nonsecreting adrenal carcinoma (2), others (12). Median size of the lesions was 3.0 cm (0.5-20 cm). Median operating time was 65 min (30-170 min). Conversion to an open procedure was necessary in 10 patients (7%). Minor morbidity occurred in nine patients (5%). Major morbidity occurred in two patients (pancreatitis, peritonitis). Median hospital stay was 3 days (1-16 days). At median follow-up of 36 months (1-105 months) five patients (4%) had persistent hypertension. No patient had evidence of recurrent hormonal excess. CONCLUSIONS: Laparoscopic removal of the adrenal gland should be considered the surgical procedure of choice in experienced minimally invasive centers.

Laparoscopic plication of the linea alba as a repair for diastasis recti - a mesh free approach.

Distasis recti is a common occurrence in multiparous women (1), caused by repeated stretching of the abdominal wall by the gravid uterus. A small proportion of patients have a persisting weakness which may be symptomatic and present to the surgeon. We would like to present a case which, thus far, has had a successful outcome from laparoscopic plication of the linea alba without mesh. The benefits of this approach are as for any laparoscopic versus open technique, most notably improved recovery time, reduced pain and wound infection. Furthermore, avoidance of a mesh negates the risks associated with insertion of a foreign body.

Oxides, onions, and other matters gastrointestinal--1996--a perspective.

A selection of landmark articles for a given year in any subject risks being somewhat subjective, and subjectivity is best avoided in scientific endeavor. However, the very nature of such a selection process invites judgment. Like most judges, I, too, claim to avoid conscious bias, but no one who has ever graced the bench can claim that at the subconscious level personal bias has never crept into a decision. Similarly, deep down in the vault of my subconscious, I love a maverick. That perhaps explains why so many articles that challenge long-held beliefs have especially found favor. Among them are those that question the strength of the association of Helicobacter pylori with gastric cancer, the usefulness of surveillance endoscopy in patients with Barrett's esophagus, a randomized trial that casts doubt on the preeminence of laparoscopic cholecystectomy, and a metaanalysis that concludes that corticosteroids may not be nearly as good for alcoholic hepatitis as we were once told. I have tried to resist the temptation to be too laudatory of technologic advancement, unless the benefit to the patient of such technology has been defined clearly. Thus, of all of the new technologies (endoscopic retrograde choledochopancreatography is no longer a new technology), only endoscopic ultrasonography finds a place. Articles that assess preventive strategies and are in the realm of epidemiology have received mention. All in all, 1996 was not a spectacular year for major therapeutic advances. In contrast, some notable advances have been made in the laboratory, and perhaps the most important has to do with the role of nitric oxide both in the regulation of normal function and in the genesis of disease.

Vitamin B12 in health and disease: part I--inherited disorders of function, absorption, and transport.

All of vitamin B12 in nature is of microbial origin. Cobalamin, as vitamin B12 should correctly be termed, is a large polar molecule that must be bound to specialized transport proteins to gain entry into cells. Entry from the lumen of the intestine under physiological conditions occurs only in the ileum and only when bound to intrinsic factor. It is transported into all other cells only when bound to another transport protein, transcobalamin II. Congenital absence or defective synthesis of intrinsic factor or transcobalamin II result in megaloblastic anemia. The Immerslund-Graesbeck syndrome, a congenital defect in the transcellular transport of cobalamin through the ileal cell during absorption, also presents with megaloblastic anemia, but with accompanying albuminuria. In most bacteria and in all mammals, cobalamin regulates DNA synthesis indirectly through its effect on a step in folate metabolism, the conversion of N5-methyltetrahydrofolate to tetrahydrofolate, which in turn is linked to the conversion of homocysteine to methionine. This reaction occurs in the cytoplasm, and it is catalyzed by methionine synthase, which requires methyl cobalamin (MeCbl), one of the two coenzyme forms of the vitamin, as a cofactor. Defects in the generation of MeCbl (cobalamin E and G diseases) result in homocystinuria; affected infants present with megaloblastic anemia, retardation, and neurological and ocular defects. 5'-Deoxyadenosyl cobalamin (AdoCbl), the other coenzyme form of cobalamin, is present within mitochondria, and it is an essential cofactor for the enzyme Methylmalonyl-CoA mutase, which converts L-methylmalonyl CoA to succinyl CoA. This reaction is in the pathway for the metabolism of odd chain fatty acids via propionic acid, as well as that of the amino acids isoleucine, methionine, threonine, and valine. Impaired synthesis of AdoCbl (cobalamin A or B disease) results in infants with methylmalonic aciduria who are mentally retarded, hypotonic, and who present with metabolic acidosis, hypoglycemia, ketonemia, hyperglycinemia, and hyperammonemia. Megaloblastic anemia does not develop in these children because adequate amounts of MeCbl are present, but the effect of methylmalonic acid on marrow stem cells may give rise to pancytopenia. Congenital absence of reductases in the cytoplasm, which normally reduce the cobalt atom in cobalamin from its oxidized to its reduced state (cobalamin C and D diseases), results in impaired synthesis of both MeCbl and AdoCbl. Both methylmalonic aciduria and homocystinuria therefore develop in these children, and they present with megaloblastosis, mental retardation, a host of neurological and ocular disorders, and failure to thrive; however, they do not have hyperglycinemia or hyperammonemia. A similar biochemical profile and clinical presentation is also seen in cobalamin F disease, which results from a defect in the release of cobalamin from lysosomes, following receptor-mediated endocytosis of the transcobalamin II-cobalamin complex into cells. It is important to recognize these inborn errors of cobalamin absorption, transport, or function as soon after birth as possible, because most respond (in some patients more fully than others) to parenteral administration of cobalamin. Delays in diagnosis can lead to grave clinical consequences.

Active absorption of vitamin B12 and conjugated bile salts by guinea pig ileum occurs in villous and not crypt cells.

We isolated highly enriched fractions of villous and crypt cells from guinea pig intestine to determine whether this preparation provided a suitable model for comparing the transport of cobalamin and conjugated bile salts by these cell populations. The uptake of [57Co] cyanocobalamin by ileal villous cells was 30-fold greater when incubated with cobalamin bound to intrinsic factor than with free cobalamin. Intrinsic factor-mediated uptake of cobalamin could not be demonstrated using ileal crypt or jejunal villous or crypt cells. When incubated with [3H] taurocholate, the uptake by ileal villous cells was significantly greater than by ileal crypt or jejunal villous cells. These results indicate the suitability of using isolated guinea pig villous and crypt cells to examine transport processes of molecules that involve specialized mechanisms. The results also demonstrate that the undifferentiated crypt cell lacks specific transport processes necessary for the active absorption of cobalamin and taurocholate.

Disorders of cobalamin (vitamin B12) absorption and transport.

Highly specialized mechanisms are required for transporting cobalamin (vitamin B12) into and out of mammalian cells. This review describes the key role of the cobalamin-binding proteins in meeting the stringent requirements for transport of this essential nutrient. Also summarized are the various defects capable of impairing intestinal absorption and transcellular transport of cobalamin. Elucidation of these defects proved crucial for our current understanding of normal cobalamin transport mechanisms.

Ultrastructure and localization of substance P and met-enkephalin immunoreactivity in the human fetal gastric antrum.

The ultrastructural localization and relations of substance P- and met-enkephalin-labeled neuronal structures were examined in the wall of the human gastric antrum during early fetal life. By 14-16 weeks of gestation, clearly discernable neural plexuses and a well developed external muscle coat were present. In the submucous coat, neural plexuses varied from immature forms consisting of 1-4 neurites partially enveloped by Schwann cell processes to more mature plexuses where neurons were completely enclosed by Schwann cell processes. Neuronal profiles with substance P- and met-enkephalin-like immunoreactivities were observed in the submucous plexus. In the myenteric plexus met-enkephalin-like immunoreactivity was seen within cell bodies and neurites. By contrast, although substance P-like immunoreactivity was observed in neurites in the myenteric plexus, no substance P-labeled somata could be identified. Unlabeled terminals were seen in contact with both unlabeled dendrites and met-enkephalinergic neurons. An increase in electron density was observed at the sites of contact. These structures probably represent early stages in the development of synaptic specializations. In addition, met-enkephalin-labeled varicosities were seen in apposition to smooth muscle cells of the circular muscle coat. This suggests that antral smooth muscle cells are directly innervated by met-enkephalin neurons.

Macromolecular secretion by isolated gastric mucosa: fundamental differences in pepsinogen and intrinsic factor secretion.

The secretion of pepsinogen and intrinsic factor (IF) in response to various known stimulators and inhibitors of gastric acid secretion was examined in isolated rabbit gastric mucosa maintained in organ culture. Acetylcholine (10(-8) M) stimulated stimulated both pepsinogen (P less than 0.01) and IF (P less than 0.01) secretion and this stimulation was blocked by atropine. Parasympatholytic agents did not alter unstimulated (basal) secretion of pepsinogen even at high concentrations (atropine, 10(-2) M or propanthelene bromide, 5 X 10(-3) M), however, at these concentrations basal IF secretion was abolished. Histamine (10(-4) and 10(-2) M) had no effect on pepsinogen secretion but stimulated IF secretion (P less than 0.001). Antagonism of H2 receptors by cimetidine reduced both basal and histamine-stimulated IF secretion, but pepsinogen secretion remained unaltered. Under the conditions of the above experiments the gastric mucosal surface was not exposed to HCl but was constantly buffered by culture medium at pH 7.4. When we applied 50 mN HCl to the mucosal surface of the biopsies, pepsinogen secretion doubled (P less than 0.001) but IF secretion was abolished. These studies have clearly documented that: (1) fundamental differences exist in the responses of pepsin and IF secreting cells; (2) H+ ions bathing the mucosal surface of the stomach may influence the results of experiments designed to examine the mechanisms of gastric mucosal macromolecular secretion.

Intestinal pseudoobstruction in acute Lyme disease: a case report.

We report here a case of acute Lyme disease in a 61-yr-old man who developed a facial nerve paralysis and a relentless intestinal pseudoobstruction 2 wk after the initial prodrome. Both the facial nerve paralysis and pseudoobstruction persisted for a month until the patient sought medical attention. Both lesions resolved only after treatment for Lyme disease was initiated. The temporal association of the pseudoobstruction with the somatic cranial neuropathy and the response of both to specific therapy for Lyme disease suggest that the former was likely the result of a reversible autonomic neuropathy or dysfunction.