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Biomedical subjects

G Marconi

Publications and source records attributed to G Marconi.

At least 55 records · Page 3Linked to original sources
PubMed1992

cAMP-mediated increase in the critical cell size required for the G1 to S transition in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, cyclic AMP is required for cellular growth. In this study we show that cAMP also specifically inhibits the G1-S transition of the S. cerevisiae cell cycle by increasing the critical cell size required at start, the major yeast cell cycle control step. In fact: (a) addition of cAMP delays the time of entering into the S budded phase of small G1 cells, while it is ineffective on large fast-growing cells. (b) If cell growth is strongly depressed, cAMP permanently inhibits cell cycle commitment of cells arrested at the alpha-factor-sensitive step. The cell fraction inhibited by cAMP is inversely correlated with the average cell size of treated populations. (c) The critical protein content (Ps) and the critical cell volume (VB) required for budding in unperturbed exponentially growing yeast populations are largely increased by cAMP. On these bases, we propose a new cAMP role at start.

Cell Cycle↗
PubMed1992

Salpingoscopy: systematic use in diagnostic laparoscopy.

OBJECTIVE: To evaluate the importance of salpingoscopy together with laparoscopy in the diagnosis of tubal pathology. DESIGN: Salpingoscopy was performed as a complementary method in patients who were subjected to diagnostic laparoscopy. The relationship between the salpingoscopy and (1) the patient's previous history of tubal disease and (2) laparoscopic diagnoses was evaluated. SETTING: Private patients referred to the Instituto de Fertilidad, Buenos Aires. PATIENTS, PARTICIPANTS: Forty-two patients undergoing a diagnostic laparoscopy during the evaluation of their fertility or as a follow-up of previous therapy. MAIN OUTCOME MEASURE(S): Salpingoscopy was performed, using a colpomicrohysteroscope. We evaluated alterations in major and minor folds and their vascularization, the presence of microadhesions, and cellular nuclei dyed with methylene blue in the tubal lumen. RESULTS: Fifty percent of the patients who had no previous history of tubal disease presented with endosalpingeal alterations, and in 37% of the normal laparoscopies the salpinx had unilateral or bilateral salpingoscopic abnormalities. CONCLUSIONS: Salpingoscopy is a useful method to evaluate oviducts, before assuming their normality, and consideration of these women for assisted reproductive technology.

Abortion, Spontaneous↗
PubMed1992

Control of breathing in patients with myasthenia gravis.

Control of breathing has seldom been investigated in patients with myasthenia gravis (MG). We evaluated lung volumes and respiratory muscle strength by measuring maximal inspiratory (MIP) and expiratory (MEP) pressures in 12 patients with moderate generalized (IIb) MG before and after an orally administered therapeutic dose (120 mg) of Mestinon, and in 11 age- and sex-matched normal subjects. Breathing pattern, mouth occlusion pressure (P0.1), and surface electromyographic activity of the diaphragm (EMGd) and intercostal (EMGint) muscles were evaluated during both room-air breathing and hypercapnic rebreathing. Before Mestinon, patients exhibited a slight decrease in VC, and normal TLC and FEV1/VC ratio. Compared with the normal control group, patients also exhibited respiratory muscle weakness (marked decrease in MIP and MEP; p less than 0.001 for both), and more rapid and shallower breathing (RSB): lower tidal volume (VT), inspiratory time (TI), expiratory time (TE), and greater respiratory frequency (f); mean inspiratory flow (VT/TI) and P0.1 were slightly supernormal, whereas both EMGd and EMGint were significantly higher in patients. During hypercapnic rebreathing, ventilation (VE) (p less than 0.001), VT (p less than 0.001), VT/TI, (p less than 0.003), P0.1 (p less than 0.003), and EMGd (p less than 0.001) response slopes to increasing PCO2 were found to be lower, whereas EMGint response slope was normal. At 60 mm Hg of PCO2 in the two groups the difference in terms of breathing pattern, P0.1, and EMGd were similar to that observed during room-air breathing. After Mestinon, VC (p less than 0.005), MIP (p less than 0.02), and MEP (p less than 0.01) significantly increased, whereas spontaneous breathing remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Biological dyschronism and circadian organization of serotonin, noradrenaline and platelet aggregation].

The importance of the environment and the increasing use of laboratory tests to study recurrent and debilitating disease have prompted studies regarding underlying biological condition with the aim of identifying suitable biological and therapeutic strategies in terms of their physiopathology. The aim of this study was to search for physiological overlaps between the circadian and serotonin (5HT), noradrenaline (NA) and platelet activity in regulating the peripheral microcirculation in a group of healthy subjects and a group of patients with recurrent and debilitating disease.

Adolescent↗
PubMed1991

Limb girdle muscular dystrophy with autosomal dominant inheritance.

We describe a patient suffering from limb-girdle muscular dystrophy with autosomal dominant inheritance proved by the presence of other similar cases in both sexes scattered over 4 generations of his family tree. In all patients the symptoms appeared in adult age and pelvi-femoral preceded scapulo-humeral involvement. Clinical expressivity has been variable, but rather benign without any reduction in life expectancy. Myopathic changes with vacuoles were present in muscle on light and electron microscopic examination. In the literature we found at least another 5 genealogies with autosomal dominant LGMD which had similar clinical and pathological features to those of our patient.

Biopsy↗
PubMed1989

Interactions of nucleic acids with distamycins. The drug monomeric chromophore.

A study of the monomeric chromophore of the oligopeptides netropsin (1), distamycin III (2), and distamycin V (3) by polarization spectroscopy techniques and molecular orbital calculations is reported. Linear dichroism spectra of the monomeric model compounds 1-methyl-2(ethylcarbamoyl)-4-acetamido-pyrrole (4) and 1-methyl-2(ethylcarbamoyl)-pyrrole (5) dissolved and oriented in lyotropic and thermotropic liquid crystals provide, together with the magnetic CD spectra, experimental checks of the theoretical calculations. The polarization directions of the investigated transition obtained by these means in this study allow us to build up in the following paper the exciton states of (1)-(3) and these provide a stereochemical interpretation of the flow linear dichroism spectra of the complexes of DNA with (2) and (3).

DNA↗
PubMed1989

Linear dichroism studies of the complexes between CT-DNA and distamycins.

The study of the monomeric chromophore of the distamycins reported in Ref. 1 was used here to build up a description of the electronic states of the whole oligopeptide by the exciton theory. Liquid crystal-linear dichroism (LC-LD) spectra of the distamycins were recorded by using as orienting solvents both thermotropic and lyotropic mesomorphic media. The agreement between the LD spectra and the polarization assignments by the exciton treatment is satisfactory. On this basis the flow-LD spectra of the complex between distamycin V and DNA was interpreted in terms of the preferred relative orientations of the guest and host molecules. A single site location of the distamycin within the minor groove does not perfectly match the experimental order parameters. This orientational distribution function could be too simple to explain the experimental data. It may therefore be assumed that a small fraction of the guest molecules are preferentially aligned more parallel to the host chain axis than the minor groove. Alternatively, and probably more likely, the partial mismatch of the experimental data with the minor groove location may be seen as a manifestation of the well-known stiffening and bending effects at the binding sites, which have already been observed by other techniques.

DNA↗
PubMed1989

Evidence for a human mitotic mutant with pleiotropic effect.

Male and female sibs born to third-cousin parents presented with mental retardation, microcephaly, short stature, juvenile onset limb-girdle muscular dystrophy and multiple chromosome mosaicism in lymphocytes and fibroblasts. Different aneuploidies (mostly trisomies) were found in 15-20% of the cells and trisomies for chromosome 8 and chromosome 7 predominated in lymphocytes and fibroblasts respectively, while monosomies were rare. Increased cellular death due to aneuploidy could explain symptoms such as mental and growth retardation and microcephaly. This could be an instance of an autosomal recessive mitotic mutant, possibly affecting a protein simultaneously involved in spindle apparatus and muscle function.

Abnormalities, Multiple↗
PubMed1988

Plasma-exchange in myasthenia gravis: a study in 20 patients.

Twenty patients with myasthenia gravis (MG) of generalized 2A and 2B types according to the Ossermann classification were treated with a course of nine plasma exchanges (PE) every two days. Before starting of the course, at the fourth exchange, and at the end of the course, the muscle balance was assessed following a special protocol. Other functions, such as respiratory function, stapedial reflex, phonation, and electro-oculographic activity were assessed and a Desmedt test was done. Three patients showed complete remission of symptoms, 8 showed good improvement and 6 mild improvement. Three showed no improvement. In total 85% of patients gained from PE. The onset of improvement was rapid in all patients but in some it lasted only a short time while in others it persisted for several weeks and even months, without the need for immunosuppressive therapy.

Adult↗
PubMed1987

Becker and limb-girdle muscular dystrophy associated with pituitary dwarfism.

In 1981 a report appeared of a patient with Duchenne muscular dystrophy associated with dwarfism caused by growth hormone deficiency, in whom the muscular disease was unusually benign. The authors suggested that the benign course might be related to the growth hormone deficiency and dwarfism. Other authors later supported this idea, having observed that in dystrophic mice and hamsters with congenital and experimentally induced pituitary dwarfism, respectively, pathological expressions of the dystrophy were markedly reduced. In this paper one case of Becker and one of limb-girdle dystrophy, each associated with short stature and growth hormone deficiency are described. In these cases the disease did not have a particularly benign course. It is concluded that caution is necessary, at least in certain cases, before an association between reduced muscular growth and the dystrophic process can be assumed.

Adolescent↗
PubMed1987

Electrophysiological studies of the visual system in myotonic dystrophy.

Ocular signs and electroretinal alterations frequently occur in Myotonic Dystrophy (MD). Surprisingly few reports describe VEP abnormalities for this syndrome. Since the evaluation of cortical visual responses is linked to an understanding of preceding retinal changes, we conducted a systematic study of the visual system including ophthalmological and electrophysiological (EOG, ERG, PERG, VEP) investigation in 14 confirmed myotonic patients. The various tests revealed consistent abnormalities, the most frequent of these being PERG and VEP changes. These alterations seemed to occur independently of one another, suggesting impaired function at different levels of visual pathway. A generalized defect of cell membrane has recently been proposed as etiopathogenesis of typical EMG and systemic features of the disease. Such membrane dysfunction might account for the early and marked abnormalities in electrophysiological tests, even in the absence of neuro-ophthalmological changes.

Adult↗
PubMed1987

[Role and possibilities of compensation filters in lateral decubitus radiographs in opaque enemas].

A wedge-shaped plexiglass compensation filter for use in lateral decubitus radiographs of double contrast barium enema examinations has been designed. This filter, which has been used since February 1985, was compared with a second plexiglass filter, made by E-Z-EM. Voltage and amperage were kept contrast. Two different experiments were conducted in order to demonstrate the benefits of routine use of this compensation filter. First, the changes in skin dose were assessed using an ionization chamber on a phantom. Secondly, three radiologists examined a series of 80 consecutive barium enemas without knowing which had been performed using the new filter. Out of the 70 examinations they considered excellent, as many as 45 had been performed with the new filter. Personal experience and the studies described show that the use of a compensation filter improves the accuracy and thus the diagnostic quality of the examinations as it enhances the detail of the anatomic structure of the colon; moreover the filter reduces skin exposure by up to 73.1% (EZ-E-EM filter 47.3%) and, at the same time, less radiographic films are needed. Routine use of a plexiglass compensation filter in lateral decubitus radiographs while performing a double contrast barium enema examination, is strongly recommended especially in obese patients.

Barium Sulfate↗
PubMed1987

Plasma-exchange in idiopathic radiculopolyneuropathies: a study in 62 patients.

The effectiveness of plasma exchange (PE) in the treatment of acute and chronic idiopathic radioculopolyneuropathies (IR) is discussed on the basis of the literature and personal data. Results of controlled trials by Swedish, French and North American groups are favourable to the use of PE in acute forms, whereas one English group found no significant differences between treated patients and controls. Dick et al. (1986) reported significant improvement also in patients with chronic forms after PE. Personal data from a non-controlled series of 62 acute and chronic IR and from a trial group of 12 acute patients and 12 controls indicated that PE--though helpful in Guillain-Barré syndrome--was not so useful in chronic forms.

Chronic Disease↗
PubMed1986

[A biological marker in drug dependence: microcirculatory homeostasis].

In 25 heroin addicts examined an initial alteration in microcirculatory homeostasis was found ond held to be responsible for the addiction. As in other cases it is thought possible to use the chronobiological course of haemodynamic balance and imbalance as a biological marker for prevention and treatment.

Biological Clocks↗