Hristo Valkov

Dr. Hristo Valkov

orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

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

Representative Publications

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9 September 2020 in Journal of Gastrointestinal and Liver Diseases
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Journal Article
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Radislav NakovRadislav Nakov
Radislav Nakov
DDDesislava Dimitrova-Yurukova
Desislava Dimitrova-Yurukova
VSVioleta Snegarova
Violeta Snegarova
MUMilena Uzunova
Milena Uzunova
ILIvan Lyutakov
Ivan Lyutakov
VNVentsislav Nakov
Ventsislav Nakov
Aims: We aimed to evaluate the prevalence of irritable bowel syndrome (IBS), functional dyspepsia (FD), and their overlap syndrome (OS) in the Bulgarian population and to assess the risk factors associated with these disorders. Methods: We sent an internet-based survey to Bulgarian adults. The survey collected data on socio- demographic, behavioral and lifestyle characteristics, and diagnostic questions following the Rome IV criteria to assess IBS, FD and their overlap occurrence. Results: Data was collected from 1,896 individuals (mean age = 35.5 years, 18-65, SD=11.7), 73.1% females. The prevalence of IBS was 20% (14% were with predominant constipation, 32% with predominant diarrhea, 52% had IBS with mixed bowel habits, and 2% unclassified IBS). Gender (p=0.005), age (p<0.001), marital status (p=0.009), occupation (p=0.001), alcohol consumption (p=0.013), sexual problems (p<0.001), FD (p<0.001), and milk intolerance (p<0.001) were significantly associated with IBS. Females (p=0.032; OR: 1.50), patients with FD (p<0.001; OR: 104.98), sexual problems (p= 0.001; ОR: 1.55 ), and milk intolerance (p<0.001; OR: 2.22) are at a higher risk of having IBS. The prevalence of FD was 12.7% (39% had postprandial distress syndrome, 33% epigastric pain syndrome, and 28% had the overlapping variant). Patients with IBS (p<0.001; OR: 127.88) and milk intolerance (p<0.001) were significantly associated with FD prevalence. The prevalence of OS was 11.7%. Gender (p=0.013), milk intolerance (p<0.001, OR: 1.65), urinary (p=0.035) and sexual problems (p<0.001, ОR: 1.80) were associated with OS prevalence. Conclusion: This is the first study to estimate the prevalence of IBS, FD, and their OS and assess the behavioral and demographic risk factors associated with these disorders in the Bulgarian population. Our results are valuable in filling in the epidemiological data gap regarding IBS, FD, and OS in Eastern Europe.

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Tsvetelina VelikovaTsvetelina Velikova
Tsvetelina Velikova
KBKonstantina Bakopoulou
Konstantina Bakopoulou
MGMilena Gulinac
Milena Gulinac
EMEvelina Manova
Evelina Manova
HVHristo Valkov
Hristo Valkov
RSRusska Shumnalieva
Russka Shumnalieva
In recent years, Meteorin-like protein (Metrnl/IL-41) and Follistatin-like 1 (FSTL1) have emerged as multifunctional molecules that play roles in immunity, metabolism and tissue remodeling. Although they demonstrate pleiotropic effects, they are promising candidates for biomarkers and possible therapeutic targets. The development of new, disease-specific biomarkers will enable clinicians to more effectively monitor inflammatory activity, more accurately assess disease severity, better predict survival, and select appropriate medical treatments. In this review, we present the role of Meteorin-Like Protein (Metrnl) and Follistatin-like 1 (FSTL1) in inflammation in autoimmune rheumatic diseases, as well as in other autoimmune pathologies, cardiovascular diseases, and metabolic diseases. Metrnl, widely expressed in different tissues and organs, is very important for inflammation, immune responses and metabolic disorders. FSTL1 also shows dynamic changes in its expression through various diseases, including cardiovascular conditions, cancer, asthma, and arthritis. Both proteins participate in multiple important signaling pathways, and understanding their diagnostic and therapeutic potential holds great scientific interest. Their complex nature requires careful evaluation of safety concerns and translation to clinical practice.

18 December 2019
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Book Chapter
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MKMila Dimitrova Kovacheva-Slavova
Mila Dimitrova Kovacheva-Slavova
TATodor Asenov Angelov
Todor Asenov Angelov
HVHristo Valkov
Hristo Valkov
HIHristo Ilianov Iliev
Hristo Ilianov Iliev
BVBorislav Georgiev Vladimirov
Borislav Georgiev Vladimirov
Autoimmune gastritis (AIG) is a chronic inflammatory disease of the gastric corpus and fundus. Although still unclear, genetic and environmental factors, antigenic mimicry or cross-reactivity are proposed pathogenic mechanisms. Parietal cells destruction results in loss of intrinsic factor and increased gastric pH due to hypochlorhydria and G-cell proliferation. Furthermore, atrophy, intestinal, pancreatic and spasmolytic polypeptide-expressing metaplasia are observed. AIG is underdiagnosed, however, proper diagnostic approach, including endoscopic, serological and histopathological assessment, is required. Gastroscopy with corpus and fundus biopsies is a gold standard. A serological combination of anti-parietal cell antibodies, intrinsic factor antibody, anti-Helicobacter pylori IgG, gastrin, pepsinogen I and pepsinogen I/II ratio improves the diagnostic sensitivity and specificity and allows atrophy level prediction. AIG might manifest with multifactorial iron deficiency anemia, vitamin B12 deficiency (pernicious anemia), neurological and neuropsychiatric conditions, small intestinal bacterial overgrowth and gastrointestinal infections. AIG association with other autoimmune diseases is well-established. Gastric cancer and gastric carcinoid are neoplastic transformations of a continuous chronic inflammation. Patients with AIG should be carefully monitored as no specific AIG therapy is available and disease complication could be fatal.

11 December 2019
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Book Chapter
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HIHristo Ilianov Iliev
Hristo Ilianov Iliev
MKMila Dimitrova Kovacheva-Slavova
Mila Dimitrova Kovacheva-Slavova
TATodor Asenov Angelov
Todor Asenov Angelov
HVHristo Valkov
Hristo Valkov
ABAli Bedran
Ali Bedran
BVBorislav Georgiev Vladimirov
Borislav Georgiev Vladimirov
The etiologic link between H. pylori infection and gastric chronic inflammation and related complications has been well established, but pathogenic pathways are still widely discussed and not sufficiently clear. The introduction of culture-independent molecular techniques has allowed better understanding of the gastric microbiota and has revealed that, when present, H. pylori represents the main colonizer but is part of a far more complex and dynamic microbiota than previously thought. This conceptual shift has made way for new pathogenic theories, focused on the interrelations between H. pylori and other gastric microbiota. Main factors that affect the gastric microbiota are gastric acidity, inflammation, and environmental factors, such as diet and drugs. Previous studies have made progress in explaining the complex interactions between gastric microorganisms in healthy individuals and their role in the development of related gastroduodenal (peptic ulcers and gastric cancer (GC)) and extraintestinal diseases, but more scientific proof is needed. This review presents current knowledge on gastric microbiota and its role in health and in the development of gastroduodenal diseases.

18 December 2019
Verified
Book Chapter
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TATodor Asenov Angelov
Todor Asenov Angelov
MKMila Dimitrova Kovacheva-Slavova
Mila Dimitrova Kovacheva-Slavova
HIHristo Ilianov Iliev
Hristo Ilianov Iliev
HVHristo Valkov
Hristo Valkov
BVBorislav Georgiev Vladimirov
Borislav Georgiev Vladimirov
Helicobacter pylori (H. pylori) is a Gram-negative spiral bacterium commonly found in the stomach. Major part of the world’s population is infected with H. pylori and is at increased risk of severe gastritis, peptic ulcer disease, and gastric cancer. Most studied virulence factors of the bacterium are the cytotoxin-associated gene (CagA) and the vacuolating cytotoxin A (VacA). The H. pylori infection is diagnosed by invasive (histological examination, culture, and rapid urease test, which require endoscopy and biopsy) and noninvasive methods (serology, urea breath test, and stool antigen test). H. pylori eradication is preferred for a long-term prevention of complications. Current treatments consist of antibiotics and adequate PPI dose and can be divided into two strands—with or without bismuth. Achieving an eradication rate of >90% is an indicator for effective treatment. Due to the increasing levels of antibiotic resistance, the standard triple therapy is largely replaced with a quadruple therapy, especially in countries with high resistance rates. Antimicrobial susceptibility testing should be performed after the second-line treatment failure, leading to an individualized patient treatment. Clear explanations and patients’ compliance are of great importance for a better outcome.

1 October 2021 in Acta Medica Bulgarica
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Journal Article
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HVHristo Valkov
Hristo Valkov
MKM. Kovacheva-Slavova
M. Kovacheva-Slavova
ILI. Lyutakov
I. Lyutakov
TAT. Angelov
T. Angelov
PGP. Getsov
P. Getsov
PPP. Penchev
P. Penchev
Diffuse idiopathic skeletal hyperostosis (DISH) is a common but underdiagnosed systemic skeletal disease. It is characterized by calcifications affecting mainly the spinal anterior longitudinal ligament. In the majority of cases, the patients are asymptomatic, but cervical osteophytes can sometimes cause hoarseness, dysphagia (DISHphagia) and even dyspnea. Case description: A 61-year-old man was admitted to our department with complaints of difficulty in swallowing and weight loss. Dysphagia had been increasing gradually for nine months. Barium swallow esophagram revealed asymmetric swallowing with expansion above the upper esophageal sphincter without other abnormalities. The extension was confirmed by esophago-gastro-duodenoscopy (EGD). Furthermore, CT scan of the thorax clearly demonstrated degenerative changes of the cervical and thoracic region, extensive ossification of the anterior longitudinal ligament, and osteophytes from C2-C7 with a forward displacement of the esophagus by 14 mm. The so-called “wax dripping down the candle” phenomenon was as well observed. Conclusion: DISH is a systematic, musculo-skeletal disease of older adults with unknown etiology. Dysphagia is the most common symptom of the disease and might be caused by osteophytes of the cervical region. We presented a case of DISH with a rare localization of the osteophytes in the cervical region C2-C7. Due to the increasing incidence of the Forestier’s syndrome and its associated “DISHphagia”, the gastroenterologist should increase the awareness of this underestimated disease and improve the diagnostic approach.