The nigrostriatal system in the presymptomatic and symptomatic stages in the MPTP monkey model: a PET, histological and biochemical study

Parkinson's disease (PD) is diagnosed when striatal dopamine (DA) loss exceeds a certain threshold and the cardinal motor features become apparent. The presymptomatic compensatory mechanisms underlying the lack of motor manifestations despite progressive striatal depletion are not well understood. Most animal models of PD involve the induction of a severe dopaminergic deficit in an acute manner, which departs from the typical, chronic evolution of PD in humans. We have used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administered to monkeys via a slow intoxication protocol to produce a more gradual development of nigral lesion. Twelve control and 38 MPTP-intoxicated monkeys were divided into four groups. The latter included monkeys who were always asymptomatic, monkeys who recovered after showing mild parkinsonian signs, and monkeys with stable, moderate and severe parkinsonism. We found a close correlation between cell loss in the substantia nigra pars compacta (SNc) and striatal dopaminergic depletion and the four motor states. There was an overall negative correlation between the degree of parkinsonism (Kurlan scale) and in vivo PET ((18)F-DOPA K(i) and (11)C-DTBZ binding potential), as well as with TH-immunoreactive cell counts in SNc, striatal dopaminergic markers (TH, DAT and VMAT2) and striatal DA concentration. This intoxication protocol permits to establish a critical threshold of SNc cell loss and dopaminergic innervation distinguishing between the asymptomatic and symptomatic parkinsonian stages. Compensatory changes in nigrostriatal dopaminergic activity occurred in the recovered and parkinsonian monkeys when DA depletion was at least 88% of control, and accordingly may be considered too late to explain compensatory mechanisms in the early asymptomatic period. Our findings suggest the need for further exploration of the role of non-striatal mechanisms in PD prior to the development of motor features.

New MRI, 18F-DOPA and 11C-(+)-alpha-dihydrotetrabenazine templates for Macaca fascicularis neuroimaging: advantages to improve PET quantification

Normalization of neuroimaging studies to a stereotaxic space allows the utilization of standard volumes of interest (VOIs) and voxel-based analysis (SPM). Such spatial normalization of PET and MRI studies requires a high quality template image. The aim of this study was to create new MRI and PET templates of (18)F-DOPA and (11)C-(+)-alpha-dihydrotetrabenazine ((11)C-DTBZ) of the Macaca fascicularis brain, an important animal model of Parkinson's disease. MRI template was constructed as a smoothed average of the scans of 15 healthy animals, previously transformed into the space of one representative MRI. In order to create the PET templates, (18)F-DOPA and (11)C-DTBZ PET of the same subjects were acquired in a dedicated small animal PET scanner and transformed to the created MRI template space. To validate these templates for PET quantification, parametric values obtained with a standard VOI-map applied after spatial normalization to each template were statistically compared to results computed using individual VOIs drawn for each animal. The high correlation between both procedures validated the utilization of all the templates, improving the reproducibility of PET analysis. To prove the utility of the templates for voxel-based quantification, dopamine striatal depletion in a representative monkey treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was assessed by SPM analysis of (11)C-DTBZ PET. A symmetric reduction in striatal (11)C-DTBZ uptake was detected in accordance with the induced lesion. In conclusion, templates of M. fascicularis brain have been constructed and validated for reproducible and automated PET quantification. All templates are electronically available via the internet.

Valor de la cirugía radioguiada con 99mTc-MIBI sensibilizada con dobutamina en el hiperparatiroidismo secundario persistente

99mTc-MIBI is a radiopharmaceutical that has been successfully used for the detection of hyperfunctioning parathyroid glands and for radioguided surgery techniques. We report on the case of a 55 year old woman in hemodialysis, with secondary persistent hyperparathyroidism after total parathyroidectomy. The conventional double-phase 99mTc-MIBI parathyroid scintigraphy was negative. The study was repeated after sensibilization with intravenous low-dose dobutamine showing an area of increased focal uptake in the lower cervical region. With this finding, radioguided 99mTc-MIBI surgery was performed after dobutamine administration, using a hand held gamma probe. The technique was considered successful with the resection of parathyroid cervical tissue which was further confirmed as nodular hyperplasia. We conclude that this methodology has the potential of being a an useful tool for the intraoperative localization of remanent tissue in patients with secondary persistent/recurrent hyperparathyroidism.

Correction of the secondary nasal tip and of alar and/or columellar collapse

The authors present their surgical technique for the correction of the secondary nasal tip with alar and/or columellar collapse. They employ a cartilage autograft in the form of an anchor or half an anchor which is taken from the auricular concha and is designed according to the requirements of the pathology to be corrected. In their experience, they have observed neither complications with the use of these grafts nor unacceptable scars in the columellar incision.

Ear replantation

The authors' tactical and technical contribution to this type of microsurgical replantation can be summarized in three main points: (1) direct sutures to the superficial temporal vessels, when these are undamaged, which simplifies the operation and makes it safer; (2) use of Kunlin's technique to make up for the great difference in diameter between the arterial vessels; and (3) deepithelialization of the posterior auricular skin to allow for creation of venous drainage channels during the first postoperative days and the enlargement of the area of contact with the recipient bed, which also helps to better immobilize the amputated part.

Secondary rhinoplasty

The correction of secondary nasal deformities produced by excessive resection poses difficult problems for the surgeon. We describe our technique using cartilage autografts. Shaping the cartilage carefully, using Rethi's incision, and immobilization of the grafts have yielded excellent results in our patients.

Mammary construction and reconstruction in one surgical stage

The authors' personal technique for mammary reconstruction, including the nipple-areola complex, is presented. The technique is simple and effective and is performed in only one surgical stage. It is applicable to mammary construction in the case of congenital absence as well as to reconstruction after mastectomy.

Correction of the secondary nasal tip

A technique used concomitantly with Rethi's incision to reach and treat the secondary nasal tip is described. The technique involves removing the cartilage remnants of both domes and placing a shaped cartilage autograft that is immobilized by sutures. No hypertrophic scarring has been observed in the 546 patients treated.

Neighboring flaps and cartilage grafts for correction of serious secondary nasal deformities

When the secondary nasal deformity is so serious that it presents loss of the soft structures, often its correction requires a neighboring flap besides the cartilage auto-grafts. In such serious cases, which are fortunately infrequent, the surgeon must resort to reconstructive techniques that typically provide very good results. Such is the case with the midforehead Indian flap, which rotated 180 degrees, allows reconstruction of the columella in the same surgical stage. In the same manner, Denonvilliers' flap may be employed to restore contour of the nasal ala, since its scar sequel is very acceptable, and Dieffenbach's flap may be used to reconstruct the columella. The flap of labial mucosa (which other authors have employed to correct septal perforations) is rotated 90 degrees to appose with another similar contralateral flap and is used to correct the seriously retracted columella. In this paper we present some cases that demanded the application of these techniques.

Vertical mammaplasty

The vertical mammaplasty technique has undeniable advantages over combined techniques. It involves only the inferior pole of the breast, thus avoiding horizontal scars, which are the ones that most frequently hypertrophy. The main disadvantage of the technique is the inferior compensation, leaving visible scars in the thorax. We have modified this technique, making the compensation at the level of the areola. With this procedure, the vertical scar does not go below the submammary fold and is easily concealed.

Two new methods for treating baldness: temporo-parieto-occipito-parietal pedicled flap and temporo-parieto-occipital free flap

We present two new flaps, a pedicled one and a free one, for the treatment of baldness. The aim of these procedures is to have the hair lying forward at the frontal region, thus providing a more natural appearance and concealing the anterior pilous implant line.

Monopedicled transposition flap for the treatment of traumatic scalp alopecias

We present some variations of the monopedicled flap with temporal pedicle, used for treatment of traumatic scalp alopecias of different origin. Emphasis is on the frontal region--the most important area aesthetically.

Reconstruction of scalp hemicircumference

We present a monopedicled diagonal frontoparietooccipital flap to reconstruct the pilous implant hemiline of the scalp. We use this design to obtain the greatest possible length, closing the donor site with an advancement flap.

Arm dermolipectomy with a quadrangular flap and "T" closure

We present a technique for the correction of obesity and/or ptosis of the arms. It consists of raising a lower quadrangular advancement flap, sliding the upper wound margin downward, cutting the excess off the quadrangular flap, and a T-shaped closure. A compressive elastic bandage is worn continuously for 3 months to help keep the closure scar flat and prevent its hypertrophy.

Ear cartilage grafts to the nose

We present our experience in the treatment of secondary nasal deformities caused by excessive resection of the nasal dorsum. We have used ear cartilage autografts, with good results and (on the whole) little or no resorption (some have been followed for 10 years). We consider it essential to correctly shape the transplant and to hold it firmly in the proper position for a period of not less than one week.

Use of rotation scalp flaps for treatment of occipital baldness

We have used 25 rotation scalp flaps to treat occipital baldness associated with fronto-parietal baldness (the third flap), and 35 such flaps for the correction of isolated occipital baldness. We have not had any flap necrosis, and our patients have been well satisfied with the results of this surgery.