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Biomedical subjects

H Franco

Publications and source records attributed to H Franco.

16 recordsLinked to original sources
PubMed2006

ELNES at magic angle conditions.

If one needs to cancel the effects of the anisotropy of the sample in a EELS experiment in the TEM, a particular couple of values for the collection and convergence angle must be used, called magic angle conditions (MAC). Recent developments in the theory have shown that a full relativistic treatment is mandatory to correctly describe this effect and that the MAC are strongly dependent on the acceleration voltage. We show how the analytical formula can be derived and give the exact analytical solution for the MAC which can then be easily applied to every practical case. We show the consequences of the energy dependence of the magic angle and that the parallelity of the beam will be the limiting factor for high acceleration voltages while for low acceleration voltages the contribution coming from Bragg spots may make it impossible to reach MAC.

Journal Article↗
PubMed2006

Cerenkov losses: a limit for bandgap determination and Kramers-Kronig analysis.

Measuring low energy losses in semiconductors and insulators with high spatial resolution becomes attractive with the increasing availability of modern transmission electron microscopes (TEMs) equipped with monochromators, C(s) correctors and energy filters. In this paper, we demonstrate that Cerenkov losses pose a limit for the interpretation of low energy loss spectra (EELS) in terms of interband transistions and bandgap determination for many materials. If the velocity of a charged particle in a medium exceeds the velocity of light, photons are emitted leading to a corresponding energy loss of a few electronvolt. Since these losses are strong for energies below the onset of interband transitions, they change the apparent loss function of semiconductors and insulators, with the risk of erroneous interpretation of spectra. We measured low energy losses of Si and GaAs with a monochromated TEM demonstrating the effect of sample thickness on Cerenkov losses. Angle resolved EELS and energy filtered diffraction patterns (taken without a monochromator) show the extremely narrow angular distribution of Cerenkov losses. The latter experiment provides a method that allows to decide whether Cerenkov radiation masks the very low loss signal in EELS.

Journal Article↗
PubMed2005

Paracoccidioides brasiliensis, paracoccidioidomycosis, and antifungal antibiotics.

Paracoccidioides brasiliensis is the causative agent of paracoccidioidomycosis (PCM), a human systemic, chronic and progressive mycosis. Preferred antifungals are sulfamethoxazol-trimethoprim, itraconazole, amphotericin B. Treatment is lengthy, the drugs may have undesirable side effects, and some are costly. Occasional resistant strains have been reported. Therefore, the search for more selective and efficient antifungals to treat this and other mycoses continues. Ajoene, chemically derived from garlic, behaves as an antifungal agent against P. brasiliensis and other fungi. Its antiproliferative effects in P. brasiliensis are associated with a reduction of phosphatidyl choline, a concomitant increase in its precursor phosphatidyl ethanolamine, and a large increase in unsaturated fatty acids in the pathogenic yeast phase. The sterol biosynthetic pathway has been largely studied for the search of antifungals. Azoles and allilamines act on differents steps of this pathway. However, they may interfere with similar steps in the host. Hence, the search for drugs that may act on more specific steps is ongoing. One such step focuses on the sterol C-methylations catalyzed by the enzyme (S)-adenosyl-L-methionine: Delta(24) - sterol methyl transferase (SMT). SMT inhibitors such as azasterols and derivatives (AZA1, AZA2, AZA3) have proven highly effective as antiproliferative agents against protozoa and some fungi, among them, P. brasiliensis. Their chemical synthesis and structure, and their molecular electrostatic potential are discussed in order to understand their mechanism of action, and derive rationally designed improvements on these molecules, that would favour a higher efficacy and selectivity.

Antifungal Agents↗
PubMed1994

HIV-1 among inner city dually diagnosed inpatients.

The objectives of this study were to investigate HIV-1 seroprevalence and risk factors, disease progression, and awareness of HIV-1 serostatus in a population of inner city, substance using, psychiatric inpatients. To pursue these goals, we tested 118 (103 M, 15 F) dually diagnosed, acute care inpatients for HIV-1 antibodies and administered structured interviews. Twenty-seven (23%, including 24 M and 3 F) of the subjects were HIV-1 seropositive. Seropositivity was twice as great among intravenous drug users and men who had sex with other men as among patients not belonging to either of these two groups. Logistic regression analysis among male subjects revealed a significantly elevated HIV-1 risk associated with a primary diagnosis of depression (odds ratio adjusted for age, race, and presence of an AIDS risk behavior = 4.2, 95% confidence interval = 1.1, 16.5; p = 0.04). Less than half of the seropositives knew their HIV-1 status prior to this study, one had AIDS and four had two or more constitutional symptoms of AIDS. The high rate of seropositivity in this indigent, dually diagnosed population presents challenges to the health-care community. That few individuals had HIV-1 related symptoms may have implications for other treatment settings.

Adult↗
PubMed1993

Age at onset of alcoholism as a predictor of homelessness and drinking severity.

The relationships between drinking history, housing history, several clinical variables and treatment retention after detoxification were evaluated in 109 inner-city alcoholics. Compared to men with a fixed abode, homeless subjects (N = 50) reported a history of alcoholism of early onset and increased severity. No differences in aftercare retention were found between homeless and non-homeless subjects.

Adult↗
PubMed1992

Crack/cocaine abusers in the general hospital: assessment and initiation of care.

OBJECTIVE: Cocaine, either smoked (as "crack") or taken intranasally, is now a common cause of psychiatric illness. This study was designed to assess the impact of cocaine abuse on a general psychiatric service and an obstetrics service in an urban general hospital and to evaluate a program for engaging affected patients in addiction treatment. METHOD: The charts of 300 general psychiatric patients (not admitted for addiction treatment) and 60 cocaine-abusing prenatal or postpartum patients were reviewed. A treatment referral program based on professionally directed peer leadership was established for patients with cocaine abuse. Results of evaluation and referral of 100 other cocaine-abusing psychiatric patients and the 60 prenatal or postpartum patients were then determined. RESULTS: Fully 64% (N = 191) of the 300 psychiatric patients were diagnosed as substance abusers; 38% (N = 113) of them abused cocaine. Almost one-third of these cocaine abusers had no axis I diagnosis other than substance abuse/dependence, and the majority were homeless. Urine samples were positive for cocaine in a majority of the obstetric patients studied. A majority of the psychiatric patients who were referred through the peer-led program enrolled in outpatient cocaine treatment--three times as many as in the chart review group. Most of the obstetric patients suitable for referral enrolled for treatment as well. CONCLUSIONS: Cocaine abuse may be responsible for a large portion of psychiatric admissions in urban public general hospitals. Cocaine abusers in psychiatric and obstetrics services are apparently responsive to a peer-oriented mode of referral into treatment.

Adult↗
PubMed1992

Treatment compliance after detoxification among highly disadvantaged alcoholics.

An outcome study was carried out on a series of 109 highly disadvantaged alcoholics discharged from the detoxification unit of a large municipal hospital in New York City. We examined the impact of a variety of clinical and demographic factors on retention in the initial phases of outpatient and inpatient treatment following discharge. Both high school completion and a history of at least 6 months of employment in the two years preceding admission correlated with frequency of registration for continued aftercare. Measurements of cognitive flexibility correlated with frequency of aftercare completion. An association strongly approaching significance was also found between length of hospital stay and aftercare completion. Some suggestions are made as to the assessment and aftercare planning for highly disadvantaged alcoholics.

Adult↗
PubMed1992

Crack cocaine use and sexual behavior among psychiatric inpatients.

Rises in both crack cocaine use and incidence of sexually transmitted diseases have been recently reported. In this study, we investigated the relationship between crack cocaine abuse and sexual behavior in 50 psychiatric inpatients. The relationship between crack use and sexual behavior is a very complicated one, influenced by many variables such as the dose of crack used, the user's preexisting sexuality, gender, and psychiatric illness. Results indicated that while most of the subjects developed sexual disinterest and dysfunction with prolonged crack cocaine use, some of them became more sexually promiscuous and consequently contracted more sexually transmitted diseases. The implications of these findings regarding transmission of HIV among crack cocaine users are discussed.

Adult↗
PubMed1991

Effect of drugs of abuse on psychiatric symptoms among hospitalized schizophrenics.

In a group of 71 inpatient schizophrenics with no other concurrent psychiatric diagnosis except for dependence on one drug, we ascertained the subjective effect their drug of abuse had on their psychiatric symptoms 2 weeks prior to hospitalization. Psychiatric symptoms were assessed by means of the Hopkins Symptom Checklist (Revised) (SCL-90R). Cocaine addicts, but not alcoholics, reported aggravation more often than improvement of symptoms. Alcoholics reported alcohol-induced symptom improvement with a similar frequency as alcohol-induced symptom aggravation.

Adult↗
PubMedDate not supplied

Self-medication among addicts with primary psychiatric disorders.

Thirty-two dually diagnosed inpatients described drug-induced changes in their psychiatric symptoms. All heroin addicts and most alcoholics reported drug-induced improvement of their primary psychiatric symptoms; all cocaine addicts reported symptom worsening. These findings suggest that chronic cocaine abuse may not necessarily be related to attempts at self-medication of psychiatric symptoms.

Adult↗
PubMedDate not supplied

Empirical assessment of the self-medication hypothesis among dually diagnosed inpatients.

The aim of this study was to empirically determine the expected effects of drugs of abuse on the psychiatric symptoms of individuals dependent on alcohol and other drugs to assess the validity of the self-medication hypothesis, defined as motivation of patients to seek a specific drug for relief of a particular set of symptoms. Eight-three inpatients in a large metropolitan hospital with an axis I diagnosis of one drug dependence and an axis II diagnosis of personality disorder completed the Hopkins Symptom Checklist-Revised (HSCL-90-R) and the Neuropsychological Impairment Scale (NIS). They also reported the effect of their drug of choice on each of the symptoms included in both tests. Heroin addicts reported that heroin improved some of their psychiatric symptoms and all of their cognitive dysfunctions. Both cocaine and alcohol users reported that their drug of choice worsened their psychiatric and cognitive symptoms. No relationship was found between frequency or severity of symptoms and drug choice. We concluded that attempts at self-medication may have occurred among heroin addicts, but were unlikely among alcoholics and cocaine addicts. We found no evidence in support of the self-medication hypothesis as a necessary reinforcer of continued drug use.

Adaptation, Psychological↗
PubMedDate not supplied

Combining behavioral and self-help approaches in the inpatient management of dually diagnosed patients.

The combination of a token economy and a self-help model made it feasible to organize and maintain an intensive dual-diagnosis treatment program in a public municipal hospital acute psychiatric ward. The program described here, which integrates the token economy and 12-step approaches, fosters voluntary and active patient participation in the process of simultaneous recovery from mental illness and addiction; it also networks the patient with community resources. Implementation of the clinical program involved addressing multiple clinical and organizational obstacles, including a multihandicapped and often nonmotivated patient population, a lack of psychiatric staff trained in managing substance abuse, and the need to integrate mental health with substance abuse clinical interventions. The program has been operating more than 5 years and has treated more than 1,000 patients. As the token economy became an integral part of the ward routine, violence on the ward declined substantially, and patient participation in group activities increased significantly.

Activities of Daily Living↗