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Biomedical subjects

J M Nazzaro

Publications and source records attributed to J M Nazzaro.

9 recordsLinked to original sources
PubMed1994

"Trap door" exposure of the cervicothoracic junction. Technical note.

This report describes a "trap door" exposure of the cervicothoracic junction. The method combines a standard anterior approach to the spine along the medial border of the sternocleidomastoid muscle with both a partial median sternotomy and an anterolateral thoracotomy. Transection of the clavicle is not required and the sternoclavicular joint is preserved. With this method, all important ventral paravertebral vessels, nerves, and associated soft tissue are fully identified and readily mobilized as needed. The method provides full bilateral anterior exposure from the C-4 through at least the T-3 vertebral levels, as well as unilateral anterolateral access to the upper thoracic spine.

Cervical Vertebrae↗
PubMed1992

Further refinement of the Escherichia coli brain abscess model in rat.

The rat brain abscess model provides a substrate for the modeling of delivery of therapeutic agents to intracerebral mass lesions. We now report refinement of the Escherichia coli brain abscess model in rat. A K1 surface antigen-negative E. coli isolated from human blood culture was stereotaxically inoculated into deep brain sites. Histopathologic analyses and quantitative cultures demonstrated the consistent production of lesions. No animal in this consecutive series developed meningitis, ventriculitis or sepsis. By contrast, prior experience with E. coli abscess production resulted in 25% failure rate of abscess production or death from sepsis. This improvement in the model may be attributable to specific characteristics of the bacteria used, modification of the inoculation method or the intracerebral placement technique. The present work suggests a reliable and consistent brain abscess model, which may be further used to study brain suppuration.

Animals↗
PubMed1992

Neuro-ophthalmological function of patients with pineal region tumors approached transtentorially in the semisitting position.

To optimize orientation and operative exposure for aggressive resection, the authors approached pineal region tumors transtentorially with the patient in a semisitting position. In the current report, 12 consecutive patients were evaluated to document operative ocular morbidity referable to the brain stem as well as visual deficits secondary to occipital lobe retraction. Before craniotomy, ophthalmological findings related to dorsal midbrain dysfunction were evident in four of the 10 patients who had previously undergone ventricular shunting. The other patients developed a partial or complete Parinaud's syndrome in the early postoperative period and some suffered additional deficits such as cranial nerve palsies. These deficits improved to varying degrees in all patients. Although each had full visual fields preoperatively, an absolute or incomplete left homonymous hemianopsia developed in the immediate postoperative period. Such visual field deficits fully resolved over a variable period of time in 10 of the 12 patients. One patient has a permanent left homonymous hemianopsia, while another has a left homonymous paracentral scotoma. Eight patients were able to return to preoperative pursuits. While ocular abnormalities related to dorsal midbrain dysfunction are most probably independent of operative approach, visual field deficits attributable to occipital lobe retraction were common in patients after a occipital transtentorial approach performed in the semisitting position. Reading difficulties associated with ocular motor dysfunction due to dorsal midbrain involvement represent the principal long-term neuro-ophthalmological complaint of patients who have undergone pineal region surgery.

Adolescent↗
PubMed1990

The role of surgery in the management of supratentorial intermediate and high-grade astrocytomas in adults.

In this analysis, the authors review studies over the last 50 years addressing the association between long-term survival and type of surgical management in adults with supratentorial intermediate or high-grade astrocytomas. Earlier reports are included because they are repeatedly referenced in current works and clearly are an important basis upon which present attitudes are predicated. Because recent work has definitively demonstrated the significance of prognostic variables on outcome, the handling of such factors in studies that investigated survival data according to degree of surgery is emphasized. Study design, experimental methods used, and methods of data analysis are also examined. This analysis shows that there is little justification for dogmatic statements concerning the relationship between increasing patient survival times and aggressive surgical management in adults with supratentorial intermediate or high-grade astrocytomas, if patients receive postoperative radiotherapy.

Adult↗
PubMed1981

Pentobarbital induces a naloxone-reversible decrease in mesolimbic self-stimulation threshold.

The effects of sodium pentobarbital and naloxone were tested on intracranial self-stimulation (ICSS) in rats implanted with electrodes in the ventral tegmental area. Threshold for ICSS was determined using a rate-independent current titration paradigm. A low dose of pentobarbital (5 mg/kg) did not have a significant effect on ICSS thresholds, while a high dose (20 mg/kg) rendered the subjects too ataxic to respond reliably in the operant task. An intermediate dose (10 mg/kg) induced a highly significant lowering of threshold (17% below saline baseline levels) without apparent deterioration in response capability. The concurrent administration of naloxone (2 mg/kg) significantly reversed the pentobarbital-induced threshold decrease, while naloxone treatment alone had no effect on the ICSS threshold.

Animals↗
PubMed1981

Morphine differentially affects ventral tegmental and substantia nigra brain reward thresholds.

In order to differentiate the roles of the nigrostriatal and mesolimbic-mesocortical dopamine systems in the action of opiates on dopaminergically mediated intracranial self-stimulation (ICSS), the effects of chronic morphine administration and acute naloxone administration on ICSS were tested in rats with electrode placements in the substantia nigra pars compacta (A-9) and the ventral tegmentum (A-10). Acute morphine (5.0 mg/kg SC) did not affect ICSS thresholds of rats with electrodes in the A-9 nucleus when tested 1, 3, 5, and 23 hours after administration. With repeated daily administration, though, these animals showed increases in thresholds which grew progressively larger with each day of morphine treatment. This threshold elevation was not reversed by naloxone given 0.5 hour after the final morphine treatment on the fifth day. In contrast, acute morphine significantly lowered self-stimulation thresholds in rats with A-10 placements. Tolerance to this facilitatory effect was evident with chronic administration. Naloxone attentuated the lowering of threshold caused by opiate administration in these A-10 animals. The present data suggest a specificity of action of opiates on different brain systems subserving reward and reinforcement. These findings also suggest that the mesolimbic-mesocortical system may play an important role in mediating the rewarding properties of morphine.

Animals↗
PubMed1980

Selective inhibition of mesolimbic behavioral supersensitivity by naloxone.

Rats trained on ventral tegmental intracranial self-stimulation (ICSS) were unaffected by acute injection of naloxone (2 mg/kg), while acute morphine (5 mg/kg) increased ICSS rate by 46%. Chronic haloperidol (1 mg/kg/day for 21 days) produced mesolimbic dopaminergic supersensitivity, as seen by 42% increase in ICSS. Acute naloxone partially blocked this supersensitivity (to 13% over basal), while acute morphine augmented it (66% over basal). These findings suggest that enkephalinergic systems may be involved in neuroleptic-induced dopaminergic behavioral supersensitivity.

Animals↗