Mitral valve replacement with maintenance of mitral annulopapillary muscle continuity in patients with mitral stenosis

Postoperative left ventricular performance was evaluated in patients with mitral stenosis who underwent mitral valve replacement with maintenance of the continuity of the mitral anulus and papillary muscles. Mitral valve replacement with preservation of autologous chordae tendineae (n = 7) or their replacement with expanded polytetrafluoroethylene sutures (n = 14) was performed in 21 patients with mitral stenosis. Hemodynamic parameters were compared with those of 28 patients who underwent conventional mitral valve replacement and 27 patients who underwent open mitral valve commissurotomy. No deaths occurred in the early or late follow-up period. All hemodynamic parameters were improved after the operation, and no significant differences were detected among the three groups with regard to postoperative cardiac index or mitral valve area. No significant differences were observed in left ventricular end-diastolic volume index, end-systolic volume index, or contractility index, but the postoperative left ventricular ejection fraction in the chordal preservation and open commissurotomy groups was greater than that in the group having conventional mitral valve replacement. Postoperative regional shortening was greatest at the diaphragmatic portion in the chordal preservation group and at the long axis in the open commissurotomy group. In the mid-term postoperative period, although no differences were noted among the three groups in echocardiographic data or global ejection fraction measured by multigated equilibrium radionuclide angiography, the regional shortening at the anterolateral portion of the left ventricle in the chordal preservation and commissurotomy groups was greater than that in the group having conventional mitral valve replacement. Postoperative radionuclide angiography during exercise failed to demonstrate any difference between the ejection fraction in the chordal preservation group and that in the group having conventional mitral valve replacement.

Distribution of serotonin cells projecting to the pontomedullary reticular formation in the cat

Using immunohistochemistry and retrograde transport techniques, this study demonstrates that serotonin (5-HT) cells in the dorsal tegmental gray of the pons at rostrocaudal from P1 to P6 levels are sources of bilateral serotonergic projections to the gigantocellular tegmental field of the medial pontine and medullary reticular formation in the cat. The cells observed were a relatively homogeneous population of small (30 microns) to medium-sized (40 microns) cells, oval, fusiform or spindle-shaped. Rostrally and caudally located 5-HT cells in the dorsal tegmental gray tended to project to the pontine and medullary reticular formation respectively. The dendrites of these cells spread in a plane perpendicular to the long axis of the brainstem. Thin 5-HT fibers with a series of fine varicosities (0.5-1.0 microns in diameter) surrounded reticular neurons, and some of these varicosities closely apposed the proximal dendrites and somata of the reticular neurons. Both large (50 microns) and small (20-30 microns) reticular neurons were uniformly innervated by 5-HT fibers. As revealed in the present study, the serotonergic system, together with the monoaminergic and cholinergic systems, seems to be involved in behavioral state regulation.

Application of in vivo microdialysis to transdermal absorption of methotrexate in rats

Microdialysis was applied to determine the in vivo transdermal absorption of methotrexate (MTX) in rats with or without a new penetration enhancer, 1-[2-(decylthio)ethyl]azacyclopentan-2-one (HPE-101). A solution composed of 2.5 mM MTX and 3% (w/v) HPE-101 was applied to the shaved abdomen, in which a semipermeable membrane cannula of 10-mm length was inserted intracutaneously with the use of an L-shaped needle. Intradermal microdialysis was performed at a flow rate of 1.0 microL/min for 12 hr. The concentration of MTX in the dialysate was measured by fluorescence polarization immunoassay (FPIA). HPE-101 (3%, w/v) significantly increased the dermal MTX concentration from 0.06 +/- 0.04 microM in the control to 56 +/- 26 microM in the dialysate from 8 to 12 hr. HPE-101 at concentrations of 0.75, 1.5, 2.25, and 3% (w/v) enhanced the total recovery of MTX in dermal dialysate from 0 to 10 hr by approximately 5, 18, 42, and 500 times compared with the control, respectively. The microdialysis system is useful for assessing in vivo transdermal drug absorption.

Transposition of the great arteries associated with total anomalous pulmonary venous return

A case of a 1-year-old boy with combined transposition of the great arteries and total anomalous pulmonary venous return is reported. The anomalies were successfully repaired by a new atrial partitioning technique.

Renin inhibitors. III. Synthesis and structure-activity relationships of transition-state inhibitors containing dihydroxyethylene isostere at the P1-P1 site

The design, synthesis and structure-activity relationships of transition-state inhibitors containing the dihydroxyethylene isostere at the scissile site are described. The compounds with (2S,3R,4S)-4-amino-5-cyclohexyl-1-morpholino-2,3-pentanediol at the P1-P1 site are potent renin inhibitors. (2S,3R,4S)-4-[N-[(2S)-3-Ethylsulfonyl-2-(1-naphthylmethyl)propiony l]-L- norleucyl]amino-5-cyclohexyl-1-morpholino-2,3-pentanediol (2) (BW-175), which is the most potent inhibitor (IC50: 3.3 nM against human renin) in this series, poorly inhibits cathepsin D (IC50: 26000 nM) and pepsin (IC50: > 100000 nM), and thus it is specific for renin. Compound 2 contains only one amino acid and showed an oral bioavailability of 2.8% at 10 mg/kg and 9.7% at 30 mg/kg in rats. The interaction between renin and inhibitor 2 is discussed on the basis of molecular modeling studies.

Discharge properties of medullary reticulospinal neurons during postural changes induced by intrapontine injections of carbachol, atropine and serotonin, and their functional linkages to hindlimb motoneurons in cats

The present study was aimed at elucidating the pontomedullary and spinal cord mechanisms of postural atonia induced by microinjection of carbachol and restored by microinjections of serotonin or atropine sulfate into the nucleus reticularis pontis oralis (NRPo). Medullary reticulospinal neurons (n = 132) antidromically activated by stimulating the L1 spinal cord segment were recorded extracellularly. Seventy-eight of them were orthodromically activated with mono- or disynaptic latencies by stimulating the NRPo area at the site where carbachol injections effectively induced postural atonia. Most of these reticulospinal neurons (71 of 78) were located in the nucleus reticularis gigantocellularis (NRGc). Following carbachol injection into the NRPo, discharge rates of the NRGc reticulospinal neurons (29 of 34) increased, while the activity of soleus muscles decreased bilaterally. Serotonin or atropine injections into the same NRPo area resulted in a decrease in the discharge rates of the reticulospinal neurons with a concomitant increase in the levels of hindlimb muscle tone. Membrane potentials of hindlimb extensor and flexor alpha motoneurons (MNs) were hyperpolarized and depolarized by carbachol and serotonin or atropine injections, respectively. In all pairs of reticulospinal neurons and MNs (n = 11), there was a high correlation between the increase in the discharge rates and the degree of membrane hyperpolarization of the MNs. Spike-triggered averaging during carbachol-induced atonia revealed that inhibitory postsynaptic potentials (IPSPs) were evoked in 15 MNs by the discharges of nine reticulospinal neurons. Four of them evoked IPSPs in more than one MN. The mean segmental delay and the mean time to the peak of IPSPs were 1.6 ms and 2.0 ms, respectively. Axonal trajectories of reticulospinal neurons (n = 6), which evoked IPSPs in MNs, were investigated in the lumbosacral segments (L1-S1) by antidromic threshold mapping. The stem axons descended through the ventral (n = 2) and ventrolateral (n = 4) funiculi in the lumbar segments. All axons projected their collaterals to the intermediate region (laminae V, VI) and ventromedial part (laminae VII, VIII) of the gray matter. All these results suggest that the reticulospinal pathway originating from the NRGc is involved in postural atonia induced by pontine microinjection of carbachol, and that the pathway is inactivated during the postural restoration induced by subsequent injections of serotonin or atropine. It is further suggested that the pontine inhibitory effect is mediated via segmental inhibitory interneurons projecting to MNs.

Big endothelin-1 structure important for specific processing by endothelin-converting enzyme of bovine endothelial cells

Phosphoramidon-sensitive endothelin-converting enzyme of bovine endothelial cells showed substrate selectivity for big endothelin-1 (ET-1) when compared to big ET-1(1-38), big ET-2(1-37), big ET-2(1-38) and big ET-3(1-41). To investigate the big ET-1 structure important for specific conversion by the endothelin-converting enzyme, we synthesized a series of truncated analogues of big ET-1, measured the hydrolysis of their Trp21-Val22 bonds, and found that a 16-residue peptide, big ET-1(19-34), is the minimal peptide sequence. This suggests that an unusually long carboxy-terminal sequence is required for big ET-1 conversion. Alanine substitution for individual amino acids in the carboxy-terminal region of big ET-1(19-34) demonstrated that His27, Val29, Pro30, Tyr31, Gly32, Leu33 and Gly34 are more important than Asn23, Thr24, Pro25, Glu26 and Val28 for eliciting efficient hydrolysis of the Trp21-Val22 bond, even though the former residues are located at more distant positions from the cleavage sites than are the latter. These results, together with the fact that big ET-2 and big ET-3 show heterogeneity in the big ET-1 residues His27, Val28, Val29 and Gly34, suggest that the His27-Val-Val-Pro-Tyr-Gly-Leu-Gly34 sequence in the carboxy-terminal region of big ET-1 plays the most important role in selective conversion by endothelin converting enzyme.

Extracellular levels of serotonin in the medial pontine reticular formation in relation to sleep-wake cycle in cats: a microdialysis study

Extracellular levels of endogenous serotonin (5-hydroxytryptamine; 5-HT) and its major metabolite, 5-hydroxyindoleacetic acid (5-HIAA) were measured in the medial pontine reticular formation (medial PRF) of intact cats. A microdialysis probe was inserted through a guide cannula into the medial PRF. At least 12 h after the probe insertion, in vivo brain microdialysis was initiated. The perfusion rate was 1 microliters/min, and perfusate fractions at regular intervals of 20 min were collected. Changes in extracellular 5-HT levels were compared across sleep-wake states of the animals, such as waking (W), slow wave sleep (SWS) and rapid eye movement (REM) sleep. To assess sleep-wake states, EEG, EMG, EOG and PGO waves were simultaneously recorded in parallel with microdialysis of the medial PRF. Extracellular 5-HT levels were highest (20-28 fmol/20 microliters) during W. As the animals entered SWS, 5-HT levels decreased to about 90% of those during W. The state of REM sleep usually interrupted SWS for 3-8 min. During the longer periods of REM sleep, during the 20 min periods in which the perfusates were collected, we observed the lowest 5-HT levels (60-50%).

[Treatment of thoracic malignancy accompanied with cardiovascular disease]

We treated 10 cases of thoracic malignancy accompanied with cardiovascular disease. Among thoracic malignancy, 7 cases were lung cancer and 3 were esophageal cancer. Accompanied cardiovascular diseases were ischemic heart disease (2 cases), valvular disease (3 cases), WPW syndrome (1 case), aortic aneurysm (4 cases). The mean age was 66, ranged from 51 to 79. The simultaneous occurrence of the two lesions were observed in 6 cases and thoracic malignancy was diagnosed after a varying interval of time following surgery of cardiovascular disease in 4 cases. In cases of thoracic malignancy accompanied with heart disease, the treatment of heart disease should precede the operation of malignant disease to reduce the risk of surgery. For the patient with esophageal cancer, posterior mediastinal esophagostomy should be applied who may have heart surgery in future. In cases of coexisting malignancy and aortic aneurysm, the priority of treatment should be determined considering the size of aneurysm. If the transverse diameter of aneurysm is larger than 7 cm, there is a high risk of rupture, so surgery for the aneurysm precedes operation of malignant diseases. It is desirable to avoid concomitant operation of malignancy and cardiovascular disease.

Replacement of chordae tendineae using expanded polytetrafluoroethylene (ePTFE) sutures during mitral valve replacement in patients with severe mitral stenosis

Since September 1991, 20 patients with mitral stenosis underwent mitral valve replacement and chordal replacement with expanded polytetrafluoroethylene (ePTFE) sutures. The continuity between the papillary muscles and the mitral annulus was maintained by four mattress sutures of ePTFE, which connected the stumps of the papillary muscle heads to the mitral annulus at the 2, 4, 8, and 10 o'clock positions. Low profile bileaflet prosthetic valves were inserted. There was no mortality either in-hospital or during follow-up. There was no valve related morbidity, such as valve structural failure, thromboembolism, anticoagulant related hemorrhage, prosthetic valve endocarditis, or posterior left ventricular rupture. The technique of replacing chordae tendineae is described in detail.

Effect of glucose levels during the in vitro culture in synthetic oviduct fluid medium on in vitro development of bovine oocytes matured and fertilized in vitro

The present study was conducted to determine the optimal glucose levels during the in vitro culture of bovine oocytes matured and fertilized in vitro for blastocyst development. Oocytes matured in TCM-199 + 10% FCS + hormones and granulosa cells were fertilized in vitro in a TALP medium with frozen-thawed, swim-up separated, and heparin-treated spermatozoa. After insemination, 1199 oocytes were cultured for 3 days in synthetic oviduct fluid medium (SOFM) supplemented with 10% human serum (HS) and with 10 different glucose levels (0 to 5 mM), and further cultured for 5 days in SOFM + 10% HS containing 1.5 mM glucose (Experiment 1). In Experiment 2, 739 oocytes were cultured for 3 days following insemination in either SOFM + human serum albumin or SOFM + 10% HS containing 0.188 mM glucose. From Days 4 to 8, the oocytes were cultured in SOFM containing 4 different glucose levels. A high level of glucose (3.0 and 5.0 mM) at Days 0 to 3 significantly reduced the rate of blastocyst development (3.0 to 4.2%), and a yet higher (5.0 mM) glucose level at Days 4 to 8 also significantly lowered the rate of blastocyst development as compared with 1.5 mM glucose (19.5% vs 29.3%). The present results indicate that a lower level (0.188 mM: 28.8% in blastocyst development) of glucose is preferable in SOFM for the in vitro development to blastocysts at Days 0 to 3 after insemination. At Days 4 to 8, the original level (1.5 mM) of glucose contained in SOFM appears to be the most effective treatment.

Termination mode and branching patterns of reticuloreticular and reticulospinal fibers of the nucleus reticularis pontis oralis in the cat: an anterograde PHA-L tracing study

By utilizing an anterograde neural tracer, Phaseolus vulgaris leucoagglutinin (PHA-L), pontomedullary reticuloreticular connections and reticulospinal connections were studied, including their fiber trajectories and distribution of PHA-L labeled terminals in close apposition to target reticular and spinal neurons, and branching patterns of axon collaterals at the levels of the cervical and upper thoracic cord. PHA-L was focally microinjected into the medial pontine reticular formation corresponding to the nucleus reticularis pontis oralis. A great number of PHA-L labeled thin fibers descended bilaterally coursing through the medial part of the pontine and medullary reticular formation with an ipsilateral predominance. Labeled terminal boutons were closely apposed to somata of various sized pontomedullary reticular neurons. Labeled thick fibers descended ipsilaterally coursing through the ventral half of the medial longitudinal fasciculus, and further descended through the ventral funiculus of the spinal cord. At the levels of the cervical and upper thoracic cord, these reticulospinal fibers gave off axon collaterals sending terminal fibers to small- to large-sized neurons in Rexed's laminae VII and VIII. Some of the axon collaterals innervated not only ipsilateral but also contralateral gray matter. By reconstructing branching patterns of axon collaterals, each axon collateral was found to innervate spinal neurons located in a disk-like spinal segment with a width less than 1 mm.

Pontine microinjection of carbachol and critical zone for inducing postural atonia in reflexively standing decerebrate cats

Pontine carbachol injection sites critically related to the induction of postural atonia were explored in reflexively standing acute decerebrate cats. Carbachol (4.0 micrograms/0.25 microliter) and atropine (2.0 micrograms/0.25 microliter) were focally injected into the pontomedullary reticular formation, and their effects on hindlimb extensor muscle tone were studied. The effective carbachol injection sites were concentrated in the region between P 1.5 and P 3.5, H -3.0 and H -5.0, and LR 1.2 and LR 2.5 (Horsley-Clarke coordinates). The effective sites corresponded to the dorsomedial part of both the nucleus reticularis pontis oralis (NRPo) and the rostral portion of the nucleus reticularis pontis caudalis (NRPc). The mean latency to the beginning of carbachol-induced postural atonia was about 90 s (92 +/- 28 s; n = 24).

[The protective effect of continuous retrograde cerebral perfusion on the central nervous system during deep hypothermic systemic circulatory arrest]

Deep hypothermic circulatory arrest (DHCA) was introduced as an adjunct for operations involving aortic arch lesions in 1970's and has since been widely used. Profound hypothermia protects the brain and other vital organs by reducing metabolic rate. We initiated the use of continuous retrograde cerebral perfusion (CRCP) via the superior vena cava during DHCA in 1987. We studied 15 patients who required DHCA and CRCP during repair or replacement of the aortic arch. CRCP times ranged from 11 to 78 (mean +/- S.D.; 37.3 +/- 21) minutes, and minimal nasopharyngeal temperatures ranged from 13.7 to 25 (17.7 +/- 2.6) degrees C. Two patients died one month postoperatively due to preoperative disease. Three patients, who were in shock preoperatively due to cardiac tamponade, developed acute renal failure postoperatively. The remaining patients were weaned from the respirator by the 2nd postoperative day. No patient had CRCP-related complications. During CRCP, the partial pressure of oxygen (PO2), saturation of oxygen (SO2), and oxygen content significantly decreased (p < 0.001), and the partial pressure of carbon dioxide (PCO2) and CO2 content significantly increased (p < 0.001) between retrogradely perfused blood and blood draining from the arch vessels. These results most probably reflected that the aerobic metabolism of the brain was maintained by CRCP while the central nervous system was maintained in a hypothermic state, with oxygen and substrate availability, wash-out of metabolites, and buffering capacity and oncotic pressure of the blood maintained. This technique offers the potentials of sufficient metabolic support to the brain during DHCA and prolonged safe time limits of DHCA.

Comparative evaluation of left ventricular performance after mitral valve repair or valve replacement with or without chordal preservation

The clinical importance of preserving the chordae tendineae during mitral valve replacement was assessed by comparing the postoperative left ventricular performances in 68 patients who underwent mitral valve replacement (MVR) with complete chordal preservation (n = 19), conventional MVR (n = 25) or mitral valve repair (n = 24) and had full hemodynamic assessment before and after surgery. The pre- and postoperative left ventricular performances were analyzed using cineangiography, multiple-gated cardiac blood pool scintigraphy (MUGA), and echocardiography. In the early postoperative period, cineangiography revealed that the end-systolic volume index (ESVI) and the end-diastolic pressure were significantly higher in the conventional MVR group. The left ventricular ejection fraction was unchanged in the chordal preservation group, but was decreased in the mitral repair and conventional MVR groups. The end-systolic circumferential left ventricular wall stress (ESS) was significantly decreased in the chordal preservation and mitral repair groups, but was unchanged, and thus higher, in the conventional MVR group. The postoperative left ventricular contractility index (ESS/ESVI) was better in the chordal preservation than in the conventional MVR group. In the late postoperative period, both the left ventricular ejection fraction as measured by MUGA and the left ventricular fractional shortening as measured by echocardiography were significantly higher in the mitral repair and chordal preservation groups than in the conventional MVR group. This study supports the concept that the maintenance of continuity between the mitral annulus and the papillary muscles has a beneficial effect on postoperative left ventricular performance.

Role of the extracellular Ca2+ on the intracellular Ca2+ changes in fertilized and activated mouse oocytes

Changes in intracellular calcium concentration ([Ca2+]i) in fertilized mouse oocytes were measured using the calcium-sensitive dye, fura-2. After fertilization, an initial long-lasting [Ca2+]i increase was followed by a periodic [Ca2+]i increase. The periodic increase in [Ca2+]i persisted for 1 to 3 h and all fertilized oocytes extruded the second polar body within 4 h. The mean interval of periodic [Ca2+]i increase was 470 +/- 180 s (mean +/- SD). The frequency of the periodic [Ca2+]i increase depended on the extracellular calcium concentration. Verapamil and nifedipine inhibited the periodic [Ca2+]i increase. Sixty-five per cent of tested cells extruded the second polar body within 90 min of exposure to 7% ethanol. In these activated oocytes, the long-lasting [Ca2+]i increase was observed. However, no cells showed a repetitive increase in [Ca2+]i. Both release of calcium from intracellular stores and influx of extracellular calcium contribute to the increase in [Ca2+]i induced by ethanol. We conclude that the extrusion of the second polar body requires an increase in [Ca2+]i above a certain threshold level and the mobilization of calcium of both the intracellular and extracellular space in mouse oocytes.

Approach to the diagnosis of sialadenosis using sialography

Since parotid swelling is the most informative symptom of sialadenosis, we examined parotid swelling with sialography as a means of diagnosing sialadenosis. An X-ray was taken from a fixed position relative to the body, using a focus film distance (FFD) of 70 cm. To determine an "index" of parotid swelling, the distance between the submandibular bone ridge and the end of the main duct was measured on X-ray. After examination of 30 normal parotids, abnormal swelling was defined as an "index" exceeding 1.9 cm. Sixteen of 24 patients suspected of having sialadenosis showed swelling exceeding 1.9 cm. Six of 7 patients who were histologically diagnosed with sialadenosis showed swelling in excess of 1.9 cm. Our method is reproducible and recurrence of parotid swelling correlating with sialadenosis can be objectively demonstrated. Furthermore, serum amylase levels in patients who were diagnosed with sialadenosis were measured before and after sialography. After sialography serum amylase levels increased remarkably higher than those of normal subjects. Thus if a patient with underlying diseases has an "index" over 1.9 cm and his serum amylase level after sialography increases remarkably, a diagnosis of sialadenosis is likely.

Synaptic mechanisms acting on lumbar motoneurons during postural augmentation induced by serotonin injection into the rostral pontine reticular formation in decerebrate cats

Intrapontine microinjections of serotonin in acutely decerebrated cats resulted in the bilateral augmentation of the postural muscle tone of the hindlimbs. Optimal injection sites were located in the dorsomedial part of the rostral pontine reticular formation corresponding to the nucleus reticularis pontis oralis (NRPo). In this study, attempts were made to elucidate the cellular basis for the serotoninergically induced augmentation of postural muscle tone by recording the electromyographic (EMG) activity of hindlimb extensor muscles, the monosynaptic reflex responses evoked by electrical stimulation of group Ia muscle afferent fibres and the membrane potentials of hindlimb alpha-motoneurons (MNs). Serotonin injections resulted not only in the augmentation of the EMG activity of gastrocnemius soleus muscles, but also in the restoration of EMG suppression, which was induced by previous injection of carbachol into the NRPo. Extensor and flexor monosynaptic reflex responses were facilitated by serotonin injections into the NRPo. Such reflex facilitation was not induced by serotonin injections into the mesencephalic or the medullary reticular formation. Intrapontine serotonin injections resulted in membrane depolarization of extensor and flexor MNs with decreases in input resistance and rheobase. Spontaneous depolarizing synaptic potentials (EPSPs) increased in both frequency and amplitude. Peak voltage of Ia monosynaptic EPSPs also increased. Serotonin injections which followed carbachol injections resulted in membrane depolarization of MNs along with an increase in the frequency of spontaneous EPSPs and a decrease in carbachol-induced inhibitory postsynaptic potentials. Following pontine carbachol injections, antidromic and orthodromic responses in MNs were suppressed. Discharges of MNs evoked by intracellular current injections were also suppressed, but were restored following serotonin injections. These results indicate that postsynaptic excitation, presynaptic facilitation and disinhibition (withdrawal of postsynaptic inhibition) simultaneously act on the hindlimb MNs during serotonin-induced postural augmentation and restoration.

Purification of acetyl coenzyme A: deacetylacephalosporin C O-acetyltransferase from Acremonium chrysogenum

Acetyl CoA: deacetylcephalosporin C O-acetyltransferase, which catalyzes the final step of the biosynthetic pathway to cephalosporin C, was stabilized by a buffer solution containing 7-aminocephalosporanic acid and purified over 1300-fold from Acremonium chrysogenum. The purified enzyme has a molecular weight of 55,000 as measured by gel filtration. SDS-polyacrylamide gel electrophoresis showed two subunit bands corresponding to molecular weights of 27,000 and 14,000. The enzyme has an isoelectoric point at pH 4.0 and optimum activity at pH 7.5.