John Preto

Dr. John Preto


Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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29 July 2015 in Obesity Surgery
Verified
Journal Article
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FCFilipe M. Cunha
Filipe M. Cunha
JOJoana Oliveira
Joana Oliveira
JPJohn Preto
John Preto
ASAna Saavedra
Ana Saavedra
MCMaria M. Costa
Maria M. Costa
DCDavide Carvalho
Davide Carvalho

30 November 2016 in Revista Portuguesa de Pneumologia (English Edition)
Verified
Journal Article
Open access
MQM. Quintas-Neves
M. Quintas-Neves
JPJohn Preto
John Preto
MDMarta Drummond
Marta Drummond
A worldwide rise in weight and obesity is taking place, associated with an increase in several comorbid conditions, such as Obstructive Sleep Apnea (OSA). Bariatric surgery is an effective treatment approach for obesity, with resultant improvement in obesity-related comorbidities. However, the relationship between this type of treatment and OSA is not well established. This systematic review aims to assess and characterize the impact that different types of bariatric surgery have on obese OSA patients. 22 articles with stated preoperative apnea-hypopnea index (AHI), apnea index (AI) or respiratory disturbance index (RDI) were analyzed in this review. A significant improvement in AHI/AI/RDI occurred after surgery, in addition to the foreseeable reduction in body mass index (BMI). Moreover, almost every study stated a postoperative reduction of the AHI to < 20/h and/or a >50% postoperative reduction of AHI, with few exceptions. The interventions with a combined malabsorptive and restrictive mechanism, like roux-en-Y gastric bypass (RYGB), were more efficacious in resolving and improving OSA than purely restrictive ones, like laparoscopic adjustable gastric banding (LAGB). In conclusion, bariatric surgery has a significant effect on OSA, leading to its resolution or improvement, in the majority of cases, at least in the short/medium term (1-2 years). However, the different results must be interpreted with caution as there are many potential biases resulting from heterogeneous inclusion criteria, duration of follow-up, diagnostic methodology and assessed variables.

23 January 2013 in Obesity Surgery
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Journal Article
Closed access
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GFGil R. Faria
Gil R. Faria
JPJohn Preto
John Preto
Jose Costa-MaiaJose Costa-Maia
Jose Costa-Maia

Verified
Journal Article
Open access
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José Pedro Vieira de SousaJosé Pedro Vieira de Sousa
José Pedro Vieira de Sousa
HSHugo Santos Sousa
Hugo Santos Sousa
SVSofia Vieira
Sofia Vieira
RNRita Nunes
Rita Nunes
JNJorge Nogueiro
Jorge Nogueiro
ELEduardo Lima-Da-Costa
Eduardo Lima-Da-Costa
Obesity is a worldwide epidemic, and bariatric surgery is considered the primary treatment for long-term weight loss and managing obesity-related health issues. Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) are the most performed procedures. Nutritional deficiencies are a significant concern following bariatric surgery and can have serious consequences. This study aims to compare the incidence of nutritional deficiencies in patients undergoing RYGB and SG. A retrospective analysis was conducted on the nutritional status of 505 consecutive patients who underwent either RYGB or SG between January and December 2019. Data were collected regarding vitamin B12, folic acid, vitamin D, calcium, PTH, magnesium, hemoglobin, iron, ferritin, and transferrin at preoperative, 6-month, and 12-month intervals post-surgery. The RYGB group showed significantly higher excess weight loss. Vitamin B12, hemoglobin, and ferritin levels were consistently higher in the SG group throughout the study. Vitamin D deficiency was prevalent, with no significant difference between the groups. Vitamin B12 deficiency was significantly more common in the RYGB group (6 months: 17.46% vs. 4.69%, p < 0.001; 12 months: 16.74% vs. 0.93%, p < 0.001). Despite differences in their mechanisms, bariatric surgeries were associated with nutritional deficiencies. It is crucial to efficiently assess, prevent, and manage these deficiencies tailored to each surgical procedure.

29 October 2010 in Journal of Medical Case Reports
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Journal Article
Open access
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GFGil R Faria
Gil R Faria
Catarina EloyCatarina Eloy
Catarina Eloy
JPJohn Preto
John Preto
ECEduardo L Costa
Eduardo L Costa
TATeresa Almeida
Teresa Almeida
APAmadeu Pimenta
Amadeu Pimenta
Most gastric tumors are adenocarcinomas. Primary gastric adenosquamous carcinoma is a rare malignancy, mostly associated with Asian populations. It constitutes less than one percent of all gastric carcinomas and its clinical presentation is the same as adenocarcinoma. It occurs more frequently in the proximal stomach, usually presents with muscular layer invasion and tends to be found in advanced stages at diagnosis, with a worse prognosis than adenocarcinoma.

1 November 2012 in Obesity Surgery
Verified
Journal Article
Closed access
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GFGil Faria
Gil Faria
JPJohn Preto
John Preto
ECEduardo Lima da Costa
Eduardo Lima da Costa
JGJoao Guimaraes
Joao Guimaraes
CCConceição Calhau
Conceição Calhau
ATAntónio Taveira-Gomes
António Taveira-Gomes