Proximal Opening Research Articles

Reactions of benzocyclobutene chromium complexes with carbon, nitrogen and oxygen nucleophiles: nucleophilic addition and unexpected proximal ring opening reactions

Tricarbonyl(η 6-1-oxobenzocyclobutene)chromium(0) (1) can be transformed to tricarbonyl(η 6-1- endo-hydroxybenzocyclobutene) chromium(0) derivatives with substituents R (RCH 3, CHCH 2, (CH 2) 4CHCH 2, (CH 2) 4OSi(Me) 2tBu) at Cl on the exo face of the complex. The relative configuration is proven by an X-ray crystal structure analysis of the trimethylsilyl ether 8 (C 16H 18CrO 4Si: a=8.693(1), b=9.490(1), c=11.063(1) Å, α=97.51(1), β=110.32(1), γ=95.38(1)°, triclinic, space group P 1 (No.2), R=0.037, R w=0.052 for 4609 observed reflections. Attempts directed at an intramolecular cycloaddition of the ortho-quinodimethane complex derived from 17 by anion promoted ring opening unexpectedly resulted in the formation of 12 as the product of an opening of the proximal bond of the anellated ring located between the hydroxy group and the coordinated aromatic ring in 16. The fact that the intermolecular cycloaddition reaction for 16 is possible in the presence of a dienophile is taken as evidence for an equilibrium between the alcoholate 17 and the two ring opened products 16 and 18. The proximal ring opening of 6 is not observed when the free organic ligand 21 is used as the educt. Ketone complexes 1 and 25 undergo proximal ring opening reaction when treated with alcoholate or primary amines.

Aqueous Tube Shunt to a Pre-existing Episcleral Encircling Element in the Treatment of Complicated Glaucomas

The treatment of glaucoma after scleral buckling surgery is often problematic. The authors investigated a series of patients in whom a silicone tube was implanted to shunt aqueous from the anterior segment to the fibrous capsule surrounding a previously placed silicone episcleral encircling element. Thirteen patients were retrospectively reviewed. In each patient, a silicone tube was inserted through a small incision into the fibrous capsule overlying the scleral explant. In most patients, no attempt was made to secure the distal end of the tube to the silicone band. The proximal end of the tube was inserted into the eye via a needle track. Successful control of intraocular pressure (IOP) (6 mm Hg < or = final IOP or < 21 mmHg with or without medication) was ultimately achieved in 11 (85%) of 13 patients (3 of the successful patients underwent one or more surgical revisions to relieve obstruction of the proximal and/or distal tube opening). Follow-up in these patients ranged from 8 to 49 months (mean +/- standard deviation, 21.7 +/- 14.1 months). The final postoperative visual acuities were within one line of the preoperative visual acuities or had improved in 11 (85%) patients. Complications included serous choroidal detachment (3 patients; 23%), conjunctival wound leak (2 patients; 15%), hyphema (1 patient; 8%), and tube obstruction by lens, iris, vitreous, or episcleral fibrous tissue (4 patients; 31%). Aqueous tube shunt to a pre-existing episcleral encircling element is useful in treating complicated glaucomas after scleral buckling surgery. Fibrous obstruction of the external tube opening is a frequent complication in the early postoperative period, but it may be relieved by surgical revision.

Colonoscopic colostomy model in rats for colon tumorigenesis studies.

A colonoscopic colostomy model for colorectal carcinogenesis and chemoprevention was developed in F344 rats. The colon was transected at the middle of the transverse colon and sutured to two openings. The proximal opening, located on the middle line of the upper abdominal wall, was for the exit of feces. The distal one located on the left back was the colostomy for the lower part of colorectum, which was approximately 9 cm in length and isolated from the feces. The two openings of the colostomy were completely separated with at least 4 cm distance between them. The animals were treated with 1,2-dimethylhydrazine (DMH) or methylazoxymethanol acetate (MAMAc) systemically or topically. Colon tumors in the isolated colorectum were observed by colonoscopy. Twenty six tumors in the isolated colorectum were found by colonoscopy with a mean latent period of 25.6 weeks in 10/15 (66.6%) animals treated with DMH (30 mg/kg subcutaneously, weekly for 30 weeks). Twelve tumors were found by colonoscopy with a mean latent period of 32.8 weeks in 6/17 (35.3%) animals treated with MAMAc (5 mg/kg enema, weekly for 35 weeks). Tumors with 0.5 mm diameter were detected as early as 21 weeks following the first dose of DMH and 28 weeks following the first dose of MAMAc respectively. Video camera-assisted endoscopic examination detected suspected small tumors 6 weeks earlier than endoscopic evaluation alone. The number, size and location of the tumors observed by colonoscopy were significantly correlated with those observed at necropsy. The tumor growth rate was monitored weekly. The tumor growth curve was expressed as the mean tumor diameters and calculated tumor volumes. Histological study at necropsy showed that 48.1% of the tumors were adenomas and 51.9% were adenocarcinomas. With a complete fecal diversion and colonoscopy, the model is potentially useful to study colon carcinogenesis and the inhibition of colon carcinogenesis.

Release of immunoreactive somatostatin, vasoactive intestinal polypeptide (VIP), and galanin during propulsive complexes in isolated pig ileum

We studied the release of immunoreactive somatostatin, VIP, and galanin during net aboral propulsive complexes (NAP) in isolated, perfused, 80-cm segments of porcine ileum. Net aboral propulsive complexes were induced by controlled infusion of liquid (perfusion medium, 3.5 ml/min) into the proximal opening of the ileum segment. In response to liquid infusion, the ileum segments generated propulsive complexes rapidly propagating along the entire segment in the aboral direction, resulting in emptying of the luminal contents. The NAPs occurred with an average interval of 7 minutes. The concentrations of galanin, somatostatin, and VIP in the venous effluent, which in control experiments without luminal infusion did not change, increased significantly (by 63.6 ± 23.7%, 43.8 ± 31.8%, and 38.8 ± 14.6%, respectively) during NAPs and emptying. Atropine (10 −6 mol/l) and hexamethonium (10 −5 mol/l) abolished both NAP generation and peptide responses. It is concluded that the enteric neruopeptides, somatostatin, VIP, and galanin, all of which have pronounced intestinal motor effects, may participate in the generation of net aboral propulsive complexes in the ileum of the pig, possibly mainly in descending relaxation.

Unexpected proximal ring opening reactions of benzocyclobutene complexes

An unexpected opening of a proximal bond in the anellated four-membered ring of benzocyclobutene tricarbonylchromium(0) complexes occurs when the 1-hydroxy-1-hex-5-enyl complex 2 is treated with base: in general, rupture of the distal bond is observed. The reaction of tricarbonyl-η6-(1-oxobenzocyclobutene)chromium(0)1 with primary amines also causes a proximal ring-opening reaction.

The positive regulatory function of the 5'-proximal open reading frames in GCN4 mRNA can be mimicked by heterologous, short coding sequences.

Translational control of GCN4 expression in the yeast Saccharomyces cerevisiae is mediated by multiple AUG codons present in the leader of GCN4 mRNA, each of which initiates a short open reading frame of only two or three codons. Upstream AUG codons 3 and 4 are required to repress GCN4 expression in normal growth conditions; AUG codons 1 and 2 are needed to overcome this repression in amino acid starvation conditions. We show that the regulatory function of AUG codons 1 and 2 can be qualitatively mimicked by the AUG codons of two heterologous upstream open reading frames (URFs) containing the initiation regions of the yeast genes PGK and TRP1. These AUG codons inhibit GCN4 expression when present singly in the mRNA leader; however, they stimulate GCN4 expression in derepressing conditions when inserted upstream from AUG codons 3 and 4. This finding supports the idea that AUG codons 1 and 2 function in the control mechanism as translation initiation sites and further suggests that suppression of the inhibitory effects of AUG codons 3 and 4 is a general consequence of the translation of URF 1 and 2 sequences upstream. Several observations suggest that AUG codons 3 and 4 are efficient initiation sites; however, these sequences do not act as positive regulatory elements when placed upstream from URF 1. This result suggests that efficient translation is only one of the important properties of the 5' proximal URFs in GCN4 mRNA. We propose that a second property is the ability to permit reinitiation following termination of translation and that URF 1 is optimized for this regulatory function.

A surgical technique for correction of total anomalous pulmonary venous drainage

A technique was employed successfully for correction of total anomalous pulmonary venous drainage into the upper right superior vena cava. A J-shaped right atriotomy was performed; the posterior flap was sutured to the anterior border of a previously enlarged atrial septal defect. The right superior vena cava was divided above the site of drainage of the pulmonary veins, and its proximal opening closed with a suture. The pulmonary venous return was directed to the left atrium in this way. The right atrial-right superior vena caval continuity was then reestablished by an anastomosis between the previously opened right atrial appendage and the distal end of the right superior vena cava. Finally the remaining atriotomy was closed. The azygos vein must be ligated to avoid systemic unsaturation. For correction of anomalous pulmonary venous drainage into the azygos vein with this technique, ligature of the azygos vein must be placed distally to the site of anomalous drainage. Three patients, aged 2 months, 7 years, and 16 years, respectively, with different anatomic types of the anomaly, were successfully operated on with this procedure. Findings displayed from the postoperative hemodynamic, echocardiographic, and clinical evaluation are encouraging, after a follow-up period that ranges from 4 months to 4 years. The advantages of the repair are discussed.

Ontogeny of the sensilla placodea on the antennae of Aulacus striatus jurine (Hymenoptera : Aulacidae)

The pore plate sensilla of pupae and imagines of Aulacus striatus (Hymenoptera : Aulacidae) were studied by scanning and transmission electron microscopy. Our results confirm the assumption that these sensilla are derivatives of hair sensilla, probably basiconic sensilla of the Cephus (Hymenoptera : Symphyta) type. Each sensillum is innervated by about 10–20 sense cells and ensheathed by 5 enveloping cells. The innermost envelope cell is the dendritic sheath cell. In mature pupae and imagines, the dendritic sheath is reduced to a collar-like ring encircling the outer dendritic segments. In the young pupa, 2 long processes of the envelope cells 2a and 2b are in contact immediately with the epicuticle of the pore plate “Anlage”. They form the pores and the pore tubules and therefore are interpreted as trichogen cells. So far, this doubling of trichogen cells in insect sensilla has been observed only in pore plates and basiconic sensilla of Hymenoptera, and it is reported here for the first time. The rod-like process of envelope cell 2a is embedded in the half-tube like envelope cell 2b. Around this inner half cylinder envelope cell 3 forms a middle, and envelope cell 4 forms an outer half-tube. In the mature pupa, the processes of envelope cells 2a, 2b, and 3 withdraw almost completely from the pore plate canal, and thus build up the outer receptor lymph cavity that fuses with the inner receptor lymph cavity. Only envelope cell 4 remains in the pore plate canal. In the imago, the outer dendritic segments branch and extend through a proximal opening into the pore plate canal.

Estimation of biliary excretion of ureidopenicillins in healthy volunteers using marker dilution technique.

1 Aspiration of duodenal fluid and estimation of recovery by a marker dilution technique was adapted to measure the biliary excretion of two chemically related ureidopenicillins, mezlocillin and azlocillin, in healthy volunteers. 2 The drug was infused intravenously at a constant rate over a period of 6 h during which duodenal fluid was aspirated through the distal opening of a triple-lumen polyvinyl tube. 3 Drug levels in plasma, urine and duodenal fluid were determined by h.p.l.c. 4 Biliary excretion rate was calculated by multiplying the concentration in the duodenal fluid by the dilution factor resulting from the dilution of marker substance infused through the proximal opening of the triple-lumen tube. 5 Since the results obtained by the marker dilution technique are comparable to data obtained by studies in patients with t-tube drainage following biliary surgery, it can be concluded that the method is useful to measure the biliary excretion of drugs in man.

Nerve regeneration in silicone chambers: Influence of gap length and of distal stump components

The range of growth-promoting influences from a distal nerve stump on a regenerating proximal stump was determined using an experimental system in which a gap between cross-anastomosed rat sciatic nerves was encased by a cylindrical silicone chamber. Two arrangements were examined after 1 month in situ: A proximal-distal (PD) system in which both proximal and distal stumps were introduced into the ends of the chamber, and a proximal-open (PO) system in which the distal stump was omitted. When the gap was 6 mm long, a regenerated nerve extended all the way through the chamber in both the PD and PO systems. When the gap was increased to 10 mm, a similar regrowth occurred in the PD chamber, whereas in the PO chamber proximal regrowth was partial or nonexistent. When the gap was increased to 15 mm, no regeneration occurred, even in the presence of the distal stump. These observations confirm that the distal stump influences proximal regeneration and indicate that this influence can act only over a limited distance or volume. Such an influence could consist of humoral agents which support nerve growth and/or outgrowth from the distal stump.

Experimental and Clinical Evaluation of High‐Frequency Positive‐Pressure Ventilation (HFPPV) and the Pneumatic Valve Principle in Bronchoscopy under General Anaesthesia

A technique for automatic ventilation in bronchoscopy under general anaesthesia was evaluated in two types of lung model and in 23 patients (29–70 y) submitted for routine bronchoscopy. The technique uses high-frequency positive-pressure ventilation (HFPPV) and functions with a pneumatic valve derived from the bronchoscope's side-arm. This technique has been given the name bronchoscopic HFPPV. Based on earlier studies, an insufflation frequency (f) of 60 per min and a relative insufflation time (1%) of 22 % was used. In the lung models, the relationship between the total gas input (Vtot) delivered to the side-arm of the bronchoscope and the pressure/gas flow pattern created at the different openings of the bronchoscope was studied. The force created by the pneumatic valve function is regulated by adjustment of Vtot and implies a great ventilatory reserve capacity. No air entrainment occurs through the proximal opening of the bronchoscope, which implies full control of the anaesthetic gas mixture delivered to the patient. Many of the patients were considered to be high anaesthetic risks and in the patient study it is shown that the alveolar ventilation can be fully controlled by adjustment of VTOT and arterial oxygenation by adjustment of the oxygen concentration of the oxygen/nitrous oxide mixture delivered to the side-arm of the bronchoscope. Experimental and clinical evaluation shows that adequate oxygenation and ventilation can be achieved: — (a) over long periods of time, (b) in anaesthetic high risk patients, (c) with the bronchoscope in the main bronchus of the diseased lung, and (d) during instrumentation through the bronchoscope. A simple ventilation-nomogram for clinical use is proposed. Adequately used, this nomogram guarantees safe ventilation during bronchoscopic HFPPV. An FIO2 of 0.3–0.4 gives adequate arterial oxygenation.

The partial stream sampling assumption in intestinal perfusion studies.

During the past several years, the technique ofin vivo intestinal perfusion with partial stream sampling has been increasingly widely used to gather information on intestinal absorptive processes in man. The basic technique involves infusion of test solution through a proximal opening; and aspiration of samples through one or more distal openings a fixed distance apart. Samples are analyzed for test solute concentrations; from such sample data, conclusions are drawn concerning alterations in stream concentrations between the sampling sites. An underlying assumption for the validity of such a method is: that sample concentrations are the same as average stream concentrations. This assumption has not previously been precisely stated. A precise statement of it is given here, together with an analytic proof of conditions necessary and sufficient for its validity. A brief verbal comment is included to clarify the practical meaning of the analytic statement.

Structure of mutator phage Mu1 of Escherichia coli

Mu1, a temperate phage that mutates Escherichia coli upon lysogenization, was examined by electron microscopy. The phage head is 540 A in diameter with an octahedral appearance, but it may be actually an icosahedron. The contractile tail sheath is 1000 × 180 A in its extended form and 560 × 225 A in its contracted form. Cross striations in the extended sheath number 24 with about 40 A spacings. Striations on the contracted sheaths are also visible, and they vary from cross, diagonal, to axial configurations. The inner tail core is 1080 A long with an outer diameter of 80 A and an inner diameter of 27 A. Quadruplet structures are observed, the dimensions of which suggest that they could be tail core segments. Each quadruplet consists of four 27 A identical subunits. Base plates about 225 A in diameter with two or three attached 315 A tail spikes are found. A 90 A knoblike structure is located at the proximal opening of the tail core. Additional analyses indicate that Mu1 contains approximately 40% DNA and 60% protein.

Action of Morphine upon the Intestinal Propulsive Activity in Unanaesthetized Dogs

Effects of morphine (and opium) on intestinal motility were tested on dogs, with Thi ry-Vell a fistulae of the small intestine. Two dogs had two fistulae, one with intact nerves, another wholly deprived from innervation. One dog had three fistulae with intact nerves. The splanchnic nerves of this dog were afterwards interfered with bilater-ally. The propulsive rate or the passage time was measured for the loop, a cylinder-shaped sponge being inserted into the proximal opening. Morphine hydrochloride, several times purified, was mostly sub-cutaneously injected in varying doses of 4mg. to 0.005mg. per kilo, intravenously in doses of 2mg. to 0.002mg. per kilo. Opium was orally given in doses of 5mg. to 2mg. per kilo. It is needless to say that the animals were not fastened on the table, nor otherwise anaesthetized except by morphine. (1) The propulsive rate of intestines is modified largely and ex-tensively by morphine administration. The rate becomes very rapid, from the usual rate, about 1cm per 1 minute, to peristaltic rush, as rapid as about twenty to thirty times ad maximum. This rapid pas-sage period would last for a long time, for example, 6 hours on 2mg. morphine per kilo, but in fact the rapid propulsion period is interrupt-ed by development of the stagnation period, which is conditioned by an enormous and persistent increase of tone; say 5 hours, in the above example. The general outline of intestinal forward movement on poisoning with morphine is the first rapid passage period, the stagna-tion period, and the second rapid passage period, which turns then to the ordinary rate. The development of the stagnation period never implies any reduc-tion in the intestinal activities, as some previous investigators con-sider, but the reverse is true; the tone increases remarkably and persis-tently. That some authors failed to deduce properly the results they obtained from the Thiry-Vella fistula by means of a balloon and those yielded in the hands of some investigators by means of a bolus, might be due probably to the possibility that they did not extend the experimentation sufficiently long, and in consequence took the stag-nation period as a reduction of the intestinal activities. The resistance of the loop canal against inserting bolus, the colour of the loop openings, and the secretion therefrom vary correspondingly. When the passage period recovers the normal, the behaviour of the animal, the pulse rate and the properties of loop recover too. The average passage time, that is, that through the whole course of morphine poisoning, the rapid passage periods and the stagnation period together, was commonly more or less shortened, except in cases of heavy dosages, such as 4mg. and 2mg. per kilo morphine, the shortest being recorded as one third, one fourth of the normal rate. It is there-fore irrational to take the stagnation period alone into consideration, and assume it to be the chief factor for the constipation by opium al-kaloids, as some writers do. (2) The larger the dose, the longer the duration of modified pas-sage period, especially the stagnation period, and the sooner the latter sets in. With a dose as small as 0.005mg. per kilo subcutaneously, no stagnation period was observed; and it is the minimal effective dose. (3) The alteration due to morphine in the forward movement' of the intestinal loop is facilitated a little by its intravenous application and reduced slightly by the total denervation of the loop. (4) The stagnation period makes manifest just a little-sooner in the proximal portion of intestines that in the distal. (5) Double splanchnicotolny reduces in a marked way the mass of alteration of the passage rate, causable by morphine.

AN IRRIGATING PROCTOSIGMOIDOSCOPE

This appartus consists of an obdurator, tube, combination of light-carrier and lamp, telescope and irrigating apparatus. The obdurator has an olivary tip, which facilitates the introduction of the tube. The tube is 10 inches long, with a working length of 8 inches. Its distal end is oblique, and the proximal end is fitted with a large flange with a milled edge. A small segment is cut from one side to prevent rolling. A metallic plug closes the proximal opening by a conical fitting, and contains two openings. The upper opening is for the irrigating tube, which contains the light carrier and telescope. The lower opening is for the outflow tube. The latter aperture can be closed by a metallic plug containing a lens as a glass window, which magnifies the illuminated field at the distal end of the tube. The light-carrier is unique in that it has a telescopic arrangement

A method for obtaining samples of mixed venous blood in intact dogs.

In order to estimate the oxygen and carbon dioxide in mixed venous blood in intact dogs two methods are in use: (1) a tonometer method in which alveolar air and pulmonary venous blood are allowed to come into equilibrium; the air is then analyzed. (2) A method of direct puncture of the right auricle or ventricle in order to obtain venous blood. A third method is possible and is now described.We devised a cannula which can be inserted into the right ventricle through the right external jugular vein. Through this samples of mixed venous blood can be withdrawn from the right heart. The cannula is a hollow metal tube 2.5 mm. in diameter and 30 cm. long, having an obturator which is bullet shaped closing its distal end. The obturator can be withdrawn and the proximal opening closed by a small stopcock. Below the stopcock is an outlet to which a piece of rubber tubing is attached Before use the air in the cannula is replaced by sterile albolene.The operation is carried out aseptically. The skin and subcutaneous...

SUPERNUMERARY URETER WITH ABNORMAL ORIFICE

The comparative paucity of reports of cases in which there is a supernumerary ureter, together with the great relief afforded the patient after proper diagnosis and correction, makes a brief review of the subject of interest. As this is a developmental defect, a thorough understanding of the subject requires a review of the embryology. The ureter is formed from the lower part of the wolffian duct. Its distal end divides, to become implanted into the kidney protoplasm. Later the proximal end or end opening into the wolffian duct draws away, and opens separately into the sinus urogenitalis. The important theories advanced to explain bifurcated and double ureter are: Sappey: The ureteral anlage, instead of branching near the kidney, branches sooner, thus forming a bifurcated ureter. Caudmont: The condition is brought about by the partial fusing together of two kidneys. Deubierre: There is a double evagination from the wolffian duct. Any

ETIOLOGY, PATHOLOGY AND DIAGNOSIS OF APPENDICITIS.

If we would correctly estimate the tendencies of appendicitis it will be through an understanding of its etiology, pathology and diagnosis. As the varying anatomy and relations of the appendix have much to do with the origin, course and recognition of appendictis they should receive some consideration. The appendix is an organ absolutely without function. For this reason nature is attempting to rid herself permanently of its presence. At the present rate it will be many generations before it is accomplished, and until then physicians must continue its study. All organs without functional activity have less resistance to abnormal processes than those which are functionally active. Every conceivable position is occupied by the appendix, but usually its base is in the right iliac fossa. Its tip may be anywhere that its length, from one to six inches, may enable it to reach. In the female its proximal opening into the