Development of a minimally invasive technique for coronary revascularization in a porcine model.

BACKGROUND: This porcine model was designed to develop a minimally invasive method for internal mammary artery (IMA) grafting using an anterior mediastinal approach and without routine use of cardiopulmonary bypass. METHODS: Assessment was made of IMA mobilization through a small parasternal incision, the feasibility of coronary artery grafting with cardiopulmonary bypass using this approach, and conditions for off-pump bypass grafting. RESULTS: In group 1, 6 pigs underwent IMA mobilization through a 5-cm horizontal midparasternal incision. Of the 2 group 2 pigs, 1 underwent IMA grafting to the left anterior descending coronary artery and the other, bilateral IMA grafting to the left anterior descending and right coronary arteries using femoral-vessel cardiopulmonary bypass. In group 3, 4 of 10 pigs had successful off-pump grafting during retrograde regional coronary venous perfusion of arterial blood. Retrograde coronary venous perfusion could not be established in the other 6 pigs, and attempts at off-pump grafting failed. CONCLUSIONS: The study demonstrates that coronary artery grafting with the IMA by this minimally invasive off-pump method is feasible, although it draws attention to areas of concern and potential methods of correction. The model provides a realistic and important learning platform for the surgical issues involved with this minimally invasive technique.

Minimally invasive coronary artery bypass grafting: a new method using an anterior mediastinotomy.

The benefit of internal mammary artery (IMA) grafting as a long-lasting intervention for coronary artery disease is well recognized. However, largely because they are less invasive, catheter based alternatives are frequently chosen, particularly to treat single or double vessel disease. To retain the advantages of the IMA graft, and to offset the invasiveness of conventional coronary artery bypass grafting, we developed a new minimally invasive method using an anterior mediastinotomy for treating left anterior descending (LAD) or right coronary artery disease, or both. Feasibility studies using 16 pigs and a human cadaver led to approval by the Institutional Review Board for use of this procedure to treat six patients (four men, two women; mean age, 63.8 +/- 13.6 [SD] yrs) who granted informed consent. Pedicle dissection of the IMA, using video assisted thoracoscopy if necessary, was made through a 2- to 3-inch horizontal anterior mediastinotomy. The underlying LAD artery was grafted during femoral vessel cardiopulmonary bypass, with cooling to 30 degrees C, induced ventricular fibrillation, and left ventricular venting if required. Transesophageal echocardiography performed after bypass showed that two patients maintained normal wall motion and four had improvement from the original impairment. One patient suffered a recurrence of angina 4 weeks after the procedure; recatheterization showed an acutely angled IMA, subsequently corrected by balloon angioplasty. The results of follow-up dobutamine echocardiographic stress tests were negative in all patients. With this minimally invasive approach, the procedure should provide the benefits of IMA grafting with shorter hospital stay, more rapid recovery, and less overall cost.

A multicenter study of lomefloxacin versus ciprofloxacin in the treatment of complicated urinary tract infections.

Lomefloxacin is a new difluorinated quinolone antimicrobial agent with broad antibacterial activity and a long half-life which allows once-daily dosing. A multicenter, randomized trial was conducted to compare the safety and efficacy of once-daily oral lomefloxacin with twice-daily oral ciprofloxacin in the treatment of complicated urinary tract infections (UTIs). All 203 patients enrolled in the study had significant bacteriuria of - 10(5) colony-forming units/ml (CFU/ml) and clinical signs and symptoms of UTI such as dysuria, frequency, urgency, pain, or hematuria. Patients were randomized to receive either 400 mg lomefloxacin once daily (n = 101) or 250 mg ciprofloxacin twice daily (n = 102). The predominant baseline pathogen isolated from the patients in both groups was Escherichia coli. At the third visit (5-9 days post-treatment), 97.8% of patients in the lomefloxacin group and 96.8% in the ciprofloxacin group showed satisfactory bacteriologic results. Clinical success was achieved in 98.9% of patients in both treatment groups and there were no statistically significant differences between the two groups. Both drug regimens were well tolerated and no patient discontinued treatment due to adverse events. It was concluded that once-daily lemofloxacin was as effective as twice-daily ciprofloxacin in patients with complicated UTIs.

Synaptic plasticity in the cerebral cortex of mice: effects of radiation and anesthesia.

In the neuropil of layers II and III of the frontal cortex of adult mice, as seen in the electron microscope, sodium pentobarbital anesthesia alone results in a significant decrease in synaptic profile length at 1 day after anesthetization, followed by a return to normal or above normal levels after 2-28 days, while the number of synaptic profiles per unit cross section (profile incidence) is not altered; irradiation with 5-500 rad plateau argon particles significantly inhibits the profile shortening effect of anesthesia at 1 day after exposure, but this inhibition is not dose related; an inverse dose relationship in profile incidence appears at 2 days following irradiation with argon particles; at 1 to 2 hours after 150 or 220 rad x-irradiation, profile incidence is significantly reduced while the length is increased, effects that appear to be dose related and unaffected by adrenalectomy.

On the ultrastructural diversity and essence of residual bodies in neuronal ceroid-lipofuscinosis.

In 4 patients with neuronal ceroid-lipofuscinoses (NCL) (3 patients with the junvenile type, 1 patient with the late infantile type), the ultrastructural spectrum of residual bodies in the central and peripheral nervous system presented curvilinear profiles in all cases and regions investigated and many more ultrastructural patterns within and beyond regions commonly accessible to biopsy, probably due to age dependence, local tissue and cellular biochemical factors. Sampling from basal ganglia especially yielded combined curvilinear-fingerpint bodies, from peripheral ganglia additional membranous bodies. Residual bodies in NCL were present in almost every cell type, similar to the distribution of regular lipofuscin. Although the classical subgroups of NCL contain electronmicroscopically well defined residual bodies, permitting distinction of the late infantile type from the juvenile type, the ultrastructural differences are more of a quantitative than of a qualitative nature. However, they are not pathognomonic. N.m.r. spectra of ceroid and lipofuscin support the concept of their biochemical similarity, and argue against the proposition that they contain a single major component.

Effects of high-LET neon (20Ne) particle radiation on the brain, eyes and other head structures of the pocket mouse: a histological study.

A study was made of tissues from 130 pocket mice after a single head-only exposure to high-LET 20Ne particle radiation at 1000, 100 or 10 rad (nominal surface dose) with the view of obtaining base"line data regarding the effectiveness of HZE (cosmic-ray) particles during spaceflight. First seen at 2-3 weeks after exposure, necrotic neurons in the cerebrum reached peak incidence (0 . 04 per cent at 1000 rad, 0 . 003 per cent at 100 rad and less than 0 . 0005 per cent at 10 rad) after 4-5 weeks and decreased to low levels thereafter. Incidence in the cerebellum was lower. Neuroglia, cells of the subependymal matrix and dentate gyrus precursor cells suffered acute damage at 1000 and at 100 rad. At 1000 rad, enlarged hyperchromatic neuroglia, first noted at 3 weeks, increased in number up to 7 months, then declined. Alterations in the retina and olfactory epithelium were seen at 1000 rad, and reaction in the scalp at 100 rad. Damage was incurred by dentinoblasts at 10 rad. Changes similar to those observed in pocket mice were found in the brains of gerbils and C57B1 mice.

Hallervorden-Spatz syndrome.

Two siblings with Hallervorden-Spatz syndrome showed striking homotypism and homochronism. Neuropathologic examination and electron microscopic studies were done; neutron activation analysis showed an increase in the uptake of iron in the basal ganglia. Of particular relevance is the application of radioactive iron studies in the clinical course of this syndrome. These studies disclosed an increase in the uptake of iron in the area of the basal ganglia in one sibling and in another isolated patient. This procedure will be helpful toward the clinical diagnosis.

An ultrastructural study of the retina in the Jansky-Bielschowsky type of neuronal ceroid-lipofuscinosis.

A 7 1/2-year-old boy died of the Jansky-Bielschowsky type of neuronal ceroidlipofuscinosis. Although an electroretinogram showed reduced activity, pigmentary retinal atrophy was not demonstrable by ophthalmoscopy two years before death. At autopsy, the retina had severe loss of photoreceptor cells, pigment displacement, gliosis, and uniformly structured lipopigment bodies with an internal structure of curvilinear profiles in ganglionic and Müller cells, in pigment epithelia, in the remaining photoreceptors, and in the elements of the inner nuclear layer. These findings conformed to those in the juvenile type of neuronal ceroid-lipofuscinosis, differing only as to the severity.

Ultrastructural investigations of peripheral nerves in neuronal ceroid-lipofuscinoses (NCL).

Specimens of brachial plexus, sural nerve and two cranial nerves of one patient with Jansky-Bielschowsky type and 3 patients with the Spielmeyer-Sjögren type of NCL were studied by electron microscopy. Significant light microscopic changes were absent in all specimens. Ultrastructurally, curvilinear and/or fingerprint inclusions were present in each case, located chiefly in Schwann cells. These diagnostic findings were, however, overshadowed by masses of lamellar pi-granule-like cytosomes, usually not mixed with curvilinear or finger-print profiles in the juvenile cases and only rarely associated with curvilinear profiles in the late infantile case. Since secondary changes of axons and myelin sheaths were mild, these lamellar cytosomes might indicate chronic damage to Schwann cells, perhaps by "wear and tear" as seen in aging as well as NCL. On account of the abundance of pi-granules in NCL, peripheral nerve biopsy appears less suitable for confirming this diagnosis than biopsy of skin, striated muscle and rectal tissue.

Peripheral motor and sensory neuropathy of early childhood, simulating Werdnig-Hoffmann disease.

A five-year-old girl developed neurogenic muscular atrophy during infancy. On the basis of clinical findings and a muscle biopsy study a diagnosis of infantile spinal muscular atrophy, benign type II, was entertained. As the disease progressed, involvement of sensory pathways was detected by electrophysiological studies. Examination of a sural nerve specimen suggested a chronic polyneuropathy rather than spinal muscular atrophy. These findings were confirmed at autopsy by demonstrating severe loss of myelinated axons in ventral and dorsal spinal roots, peripheral nerves and dorsal columns of the spinal cord. In addition, islands of astroglial fibers were found in ventral and dorsal spinal roots, regarded as a secondary reaction to the breakdown of myelinated axons. This unusual scarring process seems to result from nerve fiber loss during the perinatal period, since radicular glial scar tissue is not known to occur in the spinal muscular atrophies of later onset. Examination of the sensory nervous system in patients with Werdnig-Hoffmann disease appears mandatory to clarify the precise disease entity leading to infantile neurogenic muscular atrophy.

Editorial: Post-therapeutic radiation injuries of the nervous system. Reflections on their prevention.

The introduction of the concept of Nominal Standard Dose and of Time, Dose Fractionation Factors ostensibly permits definition of tolerance doses for normal tissues in unequivocal terms. However, even with these refinements, tolerance doses remain, at best, guidelines, because radiobiologic effectiveness is governed not only by the effective dose, but also by individual factors, which will modify the response. Attention must be accorded to these biologic parameters, in order to prevent injury to healthy tissues. Of particular significance are the relative size or volume of the irradiated tissue, the possible presence of co-existing pathology in the exposed organ and the development of disease after tge termination of the treatment. Even if these factors are properly respected, the risk of radiation injury cannot entirely be eliminated. The radiotherapist is therefore obligated to use an approach which minimizes the exposure of the healthy nervous tissue, a goal which has become attainable with the advent of modern accelerators as radiation sources.

Significance of muscle biopsies in neuronal ceroid-lipofuscinoses.

Muscle specimens obtained at necropsy from four cases of neuronal ceroid-lipofuscinosis (NCL), three of the juvenile and one of the late infantile type, and a muscle biopsy from a fifth patient with the juvenile type of NCL, all showed curvilinear bodies typical of NCL within the muscle fibres. The pigments were autofluorescent. It appears that skeletal muscle is a reliable tissue source for the diagnosis of these disorders by biopsy.

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: III. Dosimeter design, construction, and implantation.

To detect the passage of cosmic ray particles through the heads of the pocket mice during the Apollo XVII flight, a "monitor" (dosimeter) composed of plastics was prepared and implanted under the scalp. The monitor was mounted on a platform, the undersurface of which fitted the contour of the skull. Numerous tests were run to assure that the presence of the monitor assembly beneath the scalp would be compatible with the well-being of the mice and that the capacity of the monitor to detect the traversal of cosmic ray particles would be preserved over the several weeks during which it would remain under the scalp.

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: VI. launch, flight, and recovery.

The final phase to fly five pocket mice in the Apollo XVII command module was carried out at the NASA Kennedy Space Center. Upon completion of the 13-d space flight, the package was removed from the spacecraft and, after having been purged with an oxygen-helium gas mixture, was flown to American Samo. Four of the five mice were recovered alive from the package. Analysis of the mouse that died during the flight revealed several factors that could have contributed to its death, the chief of which was massive hemorrhage in its middle ear cavities.