Efferent limb myoneural and luminal continuity and postgastrectomy gastric emptying

Delayed gastric emptying and altered upper gut transit or both are common following Roux-en-Y gastrojejunostomy and are thought to be due to altered efferent limb transit secondary to isolation of the Roux limb from the duodenal pacemaker. We postulated that preservation of myoneural continuity of the Roux limb with the duodenal pacemaker would enhance solid gastric emptying, while division of the afferent limb of a Billroth II gastrojejunostomy (B-II), isolating the efferent jejunal limb from the duodenal pacemaker, would slow gastric emptying. Solid gastric emptying was measured in 14 dogs, who then underwent gastric vagotomy and antrectomy. Eight animals were reconstructed with a Roux-en-Y gastrojejunostomy, preserving myoneural but not luminal continuity of the Roux limb with the afferent limb via a muscularis bridge, while six dogs underwent standard B-II gastrojejunostomy. Serosal electrodes were placed on the afferent and efferent jejunal limbs. Gastric emptying was restudied, with fed and fasted myoelectric recordings. The bridge was then divided to create a standard Roux, while the afferent limb was transected and reanastomosed just proximal to the gastrojejunostomy in the B-II dogs to isolate the efferent limb from the duodenal pacemaker, with repeat studies. Bridge dogs had delayed solid gastric emptying compared to their preoperative state, despite normal efferent limb motility.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasoactive intestinal peptide and substance P receptor antagonists improve postoperative ileus

Octreotide, a somatostatin analogue that inhibits the release of most gut peptides, hastens the resolution of experimental postoperative ileus, suggesting that gut peptides mediate this process. We studied the role of two gut peptides involved in the control of normal gut motility, vasoactive intestinal peptide (VIP), and substance P (SP), in the initiation and maintenance of postoperative small bowel ileus in rats by preoperative administration of VIP and SP receptor antagonists, (VIP-ra and SP-ra). Thirty male Sprague-Dawley rats (300-350 g) underwent laparotomy. One half underwent placement of a duodenal catheter for transit studies while the other half had serosal electrodes placed on the proximal jejunum for myoelectric recordings. Six days later, animals were separated into three treatment groups of five each. Control animals were pretreated with ip saline, while the others received either VIP-ra or SP-ra prior to standardized laparotomy. Following abdominal closure, [Na51]CrO4 was injected into the duodenum and the animals were sacrificed 25 min later. The small bowel was then excised and divided into 10 equal segments. Small bowel transit was calculated as the geometric center of [Na51]CrO4 distribution. The interval until the return of migrating myoelectric complexes (MMCs) was determined in animals with intestinal electrodes. VIP-ra-treated rats demonstrated a 67% improvement in the geometric center of radiolabel relative to controls and SP-ra-treated rats had a 23% improvement (3.67 +/- 0.06 VIP-ra vs 2.69 +/- 0.09 SP-ra vs 2.20 +/- 0.09 control, P < 0.01). MMCs returned 180 +/- 17 min in controls vs 99 +/- 14 min in VIP-ra-treated rats (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha-subunit of calcium/calmodulin-dependent protein kinase II enhances gamma-aminobutyric acid and inhibitory synaptic responses of rat neurons in vitro

1. Here we report that in acutely isolated rat spinal dorsal horn neurons, the gamma-aminobutyric acid-A (GABAA) receptor can be regulated by calcium/calmodulin-dependent protein kinase II (CaM-KII). Intracellularly applied, the alpha-subunit of CaM-KII enhanced GABAA-receptor-activated current recorded with the use of the whole cell patch-clamp technique. This effect was associated with reduced desensitization of GABA responses. 2. GABA-induced currents are also potentiated by calyculin A, an inhibitor of protein phosphatases 1 and 2A. 3. Conventional intracellular recordings were made from hippocampal CA1 neurons in slices to determine the effect of intracellular application of CaM-KII on inhibitory synaptic potentials evoked by electrical stimulation of the stratum oriens/alveus. The inhibitory synaptic potential was enhanced by CaM-KII; this mechanism may contribute to long-term enhancement of inhibitory synaptic transmission and may also play a role in other forms of plasticity in the mammalian brain.

Proline-rich sequences that bind to Src homology 3 domains with individual specificities

To study the binding specificity of Src homology 3 (SH3) domains, we have screened a mouse embryonic expression library for peptide fragments that interact with them. Several clones were identified that express fragments of proteins which, through proline-rich binding sites, exhibit differential binding specificity to various SH3 domains. Src-SH3-specific binding uses a sequence of 7 aa of the consensus RPLPXXP, in which the N-terminal arginine is very important. The SH3 domains of the Src-related kinases Fyn, Lyn, and Hck bind to this sequence with the same affinity as that of the Src SH3. In contrast, a quite different proline-rich sequence from the Btk protein kinase binds to the Fyn, Lyn, and Hck SH3 domains, but not to the Src SH3. Specific binding of the Abl SH3 requires a longer, more proline-rich sequence but no arginine. One clone that binds to both Src and Abl SH3 domains through a common site exhibits reversed binding orientation, in that an arginine indispensable for binding to all tested SH3 domains occurs at the C terminus. Another clone contains overlapping yet distinct Src and Abl SH3 binding sites. Binding to the SH3 domains is mediated by a common PXXP amino acid sequence motif present on all ligands, and specificity comes about from other interactions, often ones involving arginine. The rules governing in vivo usage of particular sites by particular SH3 domains are not clear, but one binding orientation may be more specific than another.

Effect of axial ligation and delivery system on the tumour-localising and -photosensitising properties of Ge(IV)-octabutoxy-phthalocyanines

Four Ge(IV)-octabutoxy-phthalocyanines (GePcs) bearing two alkyl-type axial ligands were assayed for their pharmacokinetic properties and phototherapeutic efficiency in Balb/c mice bearing an intramuscularly transplanted MS-2 fibrosarcoma. The GePcs were i.v. injected at a dose of 0.35 mumol kg-1 body weight after incorporation into either Cremophor emulsions or small unilamellar liposomes of dipalmitoyl-phosphatidylcholine (DPPC). Both the nature of the delivery system and the chemical structure of the phthalocyanine were found to affect the behaviour of the GePcs in vivo. Thus, Cremophor-administered GePcs invariably yielded a more prolonged serum retention and a larger association with low-density lipoproteins (LDLs) as compared with the corresponding liposome-delivered phthalocyanines. This led to a greater efficiency and selectivity of tumour targeting. These effects were more pronounced for those GePcs having relatively long alkyl chains (hexyl to decyl) in the axial ligands. Maximal tumour accumulation (0.67 nmol per g of tissue) was found for Ge-Pc(hexyl)2 at 24 h after injection. Consistently, the Ge-Pc(hexyl)2, administered via Cremophor, showed the highest phototherapeutic activity towards MS-2 fibrosarcoma.

Involvement of CRAF1, a relative of TRAF, in CD40 signaling

CD40 is a receptor on the surface of B lymphocytes, the activation of which leads to B cell survival, growth, and differentiation. A yeast two-hybrid screen identified a gene, CRAF1, encoding a protein that interacts directly with the CD40 cytoplasmic tail through a region of similarity to the tumor necrosis factor-alpha (TNF-alpha) receptor-associated factors. Overexpression of a truncated CRAF1 gene inhibited CD40-mediated up-regulation of CD23. A region of CRAF1 was similar to the TNF-alpha receptor-associated factors TRAF1 and TRAF2 and so defined a shared TRAF-C domain that was necessary and sufficient for CD40 binding and homodimerization. The CRAF1 sequence also predicted a long amphipathic helix, a pattern of five zinc fingers, and a zinc ring finger. It is likely that other members of the TNF receptor superfamily use CRAF-related proteins in their signal transduction processes.

Evaluation of the gel test for antibody screening in a tertiary hospital in Hong Kong; insensitivity for some cold antibodies that are reactive at 37 degrees C by conventional indirect antiglobulin tests

The antiglobulin gel test (DiaMed) was compared with conventional IAT methods in pretransfusion antibody screening in a tertiary hospital in Hong Kong. Antibody titrations showed that the gel system was more sensitive than the tube IAT method in detecting anti-D, anti-S, anti-s, but slightly less sensitive with anti-E. The gel tests detected all clinically significant warm reacting allo-antibodies detected by conventional IAT methods except one case of weak anti-E. It detected a case of anti-C missed in conventional screening. The number of serological investigations due to false positive screens, non-specific antibodies and clinically insignificant cold antibodies (anti-P, and anti-Lewis) were reduced. The gel system was fast and easy to use. It would reduce delays and inconvenience caused to patients due to false positive screens and non-specific antibodies without compromising detection of clinically significant antibodies. However, of concern was the failure to detect several cases of anti-Le(a) and anti-P1 that were reactive at 37 degrees C by conventional IAT and one case of anti-H in a patient with Parabombay A.

Effect of the delivery system on the biodistribution of Ge(IV) octabutoxy-phthalocyanines in tumour-bearing mice

The pharmacokinetic properties of the Ge(IV)-octabutoxy-phthalocyanines (GePc) with two axially ligated triethylsiloxy (GePcEt) or trihexyl-siloxy (GePcHex) chains were studied in BALB/C mice bearing a transplanted MS-2 fibrosarcoma. The GePcs were delivered to mice after incorporation into unilamellar liposomes of dipalmitoyl phosphatidylcholine (DPPC) or in an emulsion of Cremophor-EL. The Cremophor delivered GePcs were cleared from the blood circulation at a much slower rate than the liposome-delivered GePcs. At the same time, Cremophor induced a slower and reduced uptake of the GePcs in the liver and spleen while it greatly enhanced the uptake in the tumour as compared to liposomes. Maximum tumour uptake was observed at 24 h post-injection and was equivalent to 0.67 and 0.50 nmol/g, respectively, for the Cremophor delivered GePcHex and GePcEt. The corresponding values for the liposome-delivered drugs were approximately one fourth of that observed with Cremophor.

Proline-rich (PxxP) motifs in HIV-1 Nef bind to SH3 domains of a subset of Src kinases and are required for the enhanced growth of Nef+ viruses but not for down-regulation of CD4

Human immunodeficiency virus (HIV) and simian immunodeficiency virus Nef proteins contain a conserved motif with the minimal consensus (PxxP) site for Src homology region 3 (SH3)-mediated protein-protein interactions. Nef PxxP motifs show specific binding to biotinylated SH3 domains of Hck and Lyn, but not to those of other tested Src family kinases or less related proteins. A unique cooperative role of a distant proline is also observed. Endogenous Hck of monocytic U937 cells can be specifically precipitated by matrix-bound HIV-1 Nef, but not by mutant protein lacking PxxP. Intact Nef PxxP motifs are dispensable for Nef-induced CD4 down-regulation, but are required for the higher in vitro replicative potential of Nef+ viruses. Thus, CD4 down-regulation and promotion of viral growth are two distinct functions of Nef, and the latter is mediated via SH3 binding.

The first example of anti-Gya detected in Hong Kong

The incidence of anti-Gya is known to be extremely rare, and only a few examples have been reported in Japanese persons and in Caucasians. This case history reports the first example of anti-Gya detected in a Chinese person. The propositus is an 83-year-old male patient whose anti-Gya was revealed because of incompatibility of all units of blood tested by a saline indirect antiglobulin test (SIAT). Although the antibody had a titer of 512 by SIAT, 10 units of Gy(a+) red cells were transfused without any adverse effect.

Determination of DLCO and cardiac output from expired gas slopes with cardiogenic oscillations

Effects of 'cardiogenic oscillations' on alveolar plateau gas concentration slope measurements, constant expiratory pulmonary capillary blood flow, and DLCO determination have not been previously described. We examined cardiogenic oscillations during constant expiratory maneuvers to assess factors influencing magnitude of oscillations as well as effect of oscillatory phase at the start and end of exhalation measurement period on alveolar gas slope. Five normal volunteers performed repeated single breath constant exhalation vital capacity maneuvers using test gas containing 2 physiologically 'inert' gases: Helium (He Mw 4) and argon (Ar Mw 40). The mixture contained 3 absorbable gases, acetylene (C2H2 Mw 26), carbon monoxide (C18O Mw 30), and oxygen. Alveolar plateau slope, magnitude of cardiogenic oscillations, relative signal to noise ratios, and effect of cardiogenic oscillation phase on measured slope were determined for each gas. Cardiogenic oscillations were present for all inert gases. Oscillations were less evident for CO. However, the effects on calculated Qc and DLCO were negligible. Cardiac oscillations of considerable magnitude are seen during single breath constant exhalation maneuvers and affect constant expiratory gas slope calculations. Cardiogenic oscillation phase does not have a significant effect on measured Qc and DLCO using constant expiratory techniques.

Alpha subunit of calcium/calmodulin-dependent protein kinase enhances excitatory amino acid and synaptic responses of rat spinal dorsal horn neurons

1. Here we report that in acutely isolated rat spinal dorsal horn (DH) neurons, the alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA)/kainate and N-methyl-D-aspartate (NMDA) receptors can be regulated by endogenous and exogenous calcium/calmodulin-dependent protein kinase II (CaM-KII). Intracellularly applied, the alpha-subunit of CaM-KII enhanced AMPA/kainate and NMDA currents recorded with the use of the whole cell patch-clamp technique. 2. Microcystin, a nonselective phosphatases inhibitor, also enhances AMPA and NMDA responses. 3. Conventional intracellular recordings were made from substantia gelatinosa neurons in spinal cord slices to determine the effect of intracellular application of CaM-KII on excitatory synaptic potentials evoked by electrical stimulation of primary afferent fibers. Excitatory synaptic transmission was enhanced by CaM-KII, which is consistent with the importance of phosphorylation of the postsynaptic AMPA/kainate and NMDA receptor-ion complexes in the short- and long-term changes in synaptic transmission.

Identifying the measurement noise in glaucomatous testing: an artificial neural network approach

Diagnosis of visual function losses in glaucomatous patients depends to a large extent on the analysis of the data collected from corresponding psychophysical tests. One of the main difficulties in obtaining reliable data from patients in these tests is the measurement noise caused by the learning effect, inattention, failure of fixation, fatigue etc. Using Kohonen's self-organising feature map, we have developed a computational method to distinguish between the noise and true measurement and to provide an instant assessment of reliability of the computer-based visual function test. In particular we have experimented with 270 test records from glaucoma patients and glaucoma suspects and found that this method provides a satisfactory way of locating and rejecting noise in the test data, an improvement over conventional statistical methods. This method can also provide doctors with a clear view of the patient's behaviour during the test, thus assisting in their diagnostic decision making process.

Biomechanical comparison between high tibial osteotomy (HTO) and combined HTO and fibular osteotomy

The ojectives of this study were to determine the changes in the lateral ligamentous stability of knee joint that occur after performing high tibial osteotomy with and without fibular osteotomy. Utilizing cadaveric specimens, lateral ligamentous stability was assessed by calculating the length of the lateral collateral ligament, and the lateral opening at different flexion angles when varus stress was applied to the tibia. The Polhemus 3-SPACE system was used to collect motion data describing the six-degrees-of-freedom three-dimensional tibiofemoral motions. It was found that the separation distance between the two attachment points of the lateral collateral ligament decreased by an average of 5 mm at all flexion angles after performing a 5-degree valgus high tibial osteotomy. Performing an additional 5-degrees of osteotomy caused this distance to further decrease. It was further found that performing a fibular osteotomy following a 5-degree valgus high tibial osteotomy produced no changes in the length of the lateral collateral ligament. It was also found that the lateral opening increased an average of 5 mm at all flexion angles after performing a 5-degree valgus high tibial osteotomy. Performing a 10-degree osteotomy caused a further increase in the lateral opening. It was further found that performing a fibular osteotomy following a 5-degree valgus high tibial osteotomy caused the lateral opening to return to its original value. That is to say, the fibular osteotomy negated the lateral opening caused by the tibial osteotomy and produced a pattern of lateral opening similar to the one found in the intact knee.

Binding of Bruton's tyrosine kinase to Fyn, Lyn, or Hck through a Src homology 3 domain-mediated interaction

Bruton's tyrosine kinase (Btk) is a recently described B-cell-specific tyrosine kinase. Mutations in this gene lead to human X chromosome-linked agammaglobulinemia and murine X-linked immunodeficiency. Although genetic evidence strongly suggests that Btk plays a crucial role in B-lymphocyte differentiation and activation, its precise mechanism of action remains unknown, primarily because the proteins that it interacts with have not yet been identified. Here, we show that Btk interacts with Src homology 3 domains of Fyn, Lyn, and Hck, protein-tyrosine kinases that get activated upon stimulation of B- and T-cell receptors. These interactions are mediated by two 10-aa motifs in Btk. An analogous site with the same specificity is also present in Itk, the T-cell-specific homologue of Btk. Our data extend the range of interactions mediated by Src homology 3 domains and provide an indication of a link between Btk and established signaling pathways in B lymphocytes.

Evaluation of a recombinant parasite antigen for the diagnosis of lymphatic filariasis

We evaluated the usefulness of a recombinant parasite antigen (recSXP1) for the serologic diagnosis of lymphatic filariasis. A large proportion of sera from microfilaremic donors living in five different endemic countries (356 of 446 [80%]) contained IgG antibodies to recSXP1, as do sera from approximately 33% of amicrofilaremic patients with acute filarial disease and/or indirect evidence of active filarial infection. Exposure to filarial worms per se does not appear sufficient to elicit an anti-SXP1 antibody response. Thus, this serologic test identifies a large proportion of persons with active lymphatic filariasis among residents of endemic areas.

Block of induction and maintenance of calcium-induced LTP by inhibition of protein kinase C in postsynaptic neuron in hippocampal CA1 region

Calcium-induced LTP (Ca-LTP) refers to the long-lasting potentiation of synaptic transmission in hippocampal synapses that can be induced by a transient (7-10 min) and small increase (from 2 mM to 4 mM) in extracellular calcium concentration. In this paper the effects of protein kinase C (PKC) inhibitors, polymyxin B (PMB) and PKC(19-31), given intracellularly to the postsynaptic neuron in the CA1 region, on the induction and maintenance of Ca-LTP were studied and compared with those found in a similar study earlier made in this laboratory on tetanic stimulation-induced LTP (TS-LTP) [18]. When the intracellular delivery of the inhibitor(s) was made to begin 30 min before the exposure to increased [Ca2+]0, the development of Ca-LTP was completely blocked, leaving only a brief enhancement of EPSPs directly attributable to the brief increase in [Ca2+]0. When the intracellular delivery of either PKC(19-31) alone or PMB+PKC(19-31) was made to begin after the full establishment of Ca-LTP, it soon made the maintained potentiation begin to decline, the EPSP amplitude gradually returning to the control value before the exposure to increased calcium. Thus postsynaptic PKC inhibition blocks both the induction and the maintenance of Ca-LTP, just as it has been shown to do to TS-LTP. But quantitative differences exist: both the induction and the maintenance of Ca-LTP appeared to be more susceptible to block by postsynaptic PKC inhibition than those of TS-LTP.

[Retinal hemorrhage in newborn infants]

The fundi of the 527 infants born within one week were investigated. The results showed that 54 cases (78 eyes) had retinal hemorrhage. Among them, 23 cases (28 eyes) accompanied macular hemorrhage. The retinal hemorrhage in newborn infants was higher in vaginal delivery than in cesarean section, and the incidence of the fetal distress was higher in the newborn infants with macular hemorrhage. The essential causes of the retinal hemorrhage in newborn infants, development of infant macular and the mechanism of amblyopia induced by macular hemorrhage were discussed.

Transient myeloproliferative disorder in a Down's neonate with rearranged T-cell receptor beta gene and evidence of in vivo maturation demonstrated by dual-colour flow cytometric DNA ploidy analysis

Neonates with Down's syndrome may develop a transient myeloproliferative disorder (TMPD) which on presentation is indistinguishable from acute leukemia, with the difference manifest only on follow-up. The clinical course is one of spontaneous remission in TMPD and relentless progression in leukemia. We describe a Down's neonate presenting with hyperleucocytosis and circulating blasts which were positive for CD34, myeloid (CD33), megakaryocytic (CD41, CD42b, CD61), and T-lineage (CD3, CD7), but not B-lineage, associated antigens. Clonal rearrangement of the T-cell receptor beta (TCR beta) gene was found, with the immunoglobulin heavy chain gene in germline configuration, showing the disease to be a clonal proliferation of a multipotential stem cell involving the myeloid and T lineages. Dual-colour flow cytometric DNA ploidy analysis of CD41 positive blasts showed initially a predominant 2N population, but polyploidization to 6N and 8N cells was found on follow-up, concomitant with a progressive decrease in circulating blasts, suggesting maturation of the abnormal clone and a provisional diagnosis of TMPD. This was shown by the eventual resumption of normal haemopoiesis with the disappearance of blasts and the clonally rearranged TCR beta gene.

In vitro survival of skin flora in heparin locks and needleless valve infusion devices

OBJECTIVE

To determine the extent to which two types of infusion devices, the heparin lock and a needleless valve device, allowed the persistence of inoculated microorganisms.

DESIGN

Experiment.

SETTING

Clinical microbiology laboratory.

OUTCOME MEASURES

Bacterial counts in infusion devices.

INTERVENTION

Five of each type of device were inoculated with approximately 10(5) colony-forming units of a strain of Staphylococcus epidermidis and Enterobacter aerogenes and tested for growth at seven time intervals, from 10 minutes to 72 hours after inoculation.

RESULTS

Both strains of bacteria were present in each device at every time interval tested, including 72 hours after inoculation.

CONCLUSIONS

Bacteria introduced into a heparin lock or valve device may be isolated for prolonged periods of time. This suggests that if such devices are contaminated during use, they may be a potential source of infection. The risk of infection should be one major consideration in risk and benefit deliberations when choosing new products.

Induction of H3.3 replacement histone mRNAs during the precommitment period of murine erythroleukemia cell differentiation

Differential hybridization to a cDNA library made from the mRNA of differentiating mouse erythroleukemia (MEL) cells has been used to identify sequences that are induced during the early stages of MEL cell differentiation. One of the differentially expressed genes identified encodes the H3.3 histone subtype. We show here that the three polyadenylated mRNAs produced from the H3.3B gene, as well as the single mRNA produced from the related H3.3A gene, are coordinately induced during the first few hours of MEL cell differentiation and subsequently down regulated as cells undergo terminal differentiation. Nuclear run-on transcription experiments indicate that the accumulation and decay of these mRNAs are controlled at the post-transcriptional level. Unlike the polyadenylated mRNAs of two H1 histone genes that exhibit similar kinetics of induction and decay controlled by c-myc, induction of the H3.3 mRNAs is unaffected by deregulated expression of c-myc.