Determination of peracetic acid and hydrogen peroxide in a preparation

Iodometric and permanganometric titrations were used for determination of peracetic acid and hydrogen peroxide (H2O2) in the mixture. Two procedures were described and compared. Titrations could be done in only one vessel, in the same reaction mixture, when iodometric titration of peracetic acid was continued after the permanganometric titration of H2O2, (procedure A). Peracetic acid and H2O2, as oxidizing agents, reacted with potassium iodide in an acid medium, evolving iodine. This reaction was used for the quantitative iodometric determination of total peroxide in procedure B. H2O2 reacted with potassium permanganate in acid medium, but peracetic acid did not react under the same conditions. That made possible the selective permanganometric determination of H2O2 in the presence of peracetic acid. The procedure B was performed in two titration vessels (KV = 3.4% for peracetic acid, 0.6% for H2O2). The procedure A for iodometric determination of peracetic acid in one titration vessel after permanganometric titration of H2O2 was recommended (KV = 2.5% for peracetic acid, 0.45% for H2O2).     

Squamous cell lung carcinomas: the role of nm23-H1 gene

 This analysis of 32 pairs of human squamous cell lung carcinomas and normal matched control DNA demonstrates that loss of heterozygosity (LOH) is infrequent at the nm23-H1 locus, affecting only 2 of the 18 informative cases. Both LOH cases were in the tumor stage IIIA. One tumor was of poor and the other of moderate histological grade. These and an additional 34 tumor samples were also analyzed immunohistochemically for the presence of nm23-H1 protein. Of the 66 cases tested for the presence of nm23-H1 protein 54 were negative. Eight samples exhibited up to 35% positive cells (with weak immunostaining intensity) and four between 35% and 70% (moderate immunostaining intensity); no sample showed more than 70% positive cells. Noncancerous lung parts contained no nm23-H1 protein. nm23-H1 expression was independent of TNM stage, grade, tumor size, and patient’s survival. Two samples with LOH were negative for nm23-H1 protein. We therefore conclude that neither loss of heterozygosity of the nm23-H1 gene nor the intensity of specific protein expression are related to squamous cell lung carcinoma development and progression. Received: 27 January 1997 / Accepted: 9 May 1997     

Hodgkin s disease with nephrotic syndrome as a complication of ulcerative colitis: case report

We describe a case of a 32-year-old patient with ulcerative colitis complicated by Hodgkin s disease who presented with nephrotic syndrome. The patient had suffered from relapsing ulcerative colitis for 6 years before he developed Hodgkin s lymphoma. He was treated for Hodgkin s disease with 9 cycles of combined chemotherapy (COPP/ABV) and achieved the stabile remission of lymphoma, nephrotic syndrome, and ulcerative colitis. To the best of our knowledge, this is the first report on ulcerative colitis associated with Hodgkin s disease and nephrotic syndrome.     

Temptation of academic medicine: second alma mater and "shared employment' concepts as possible way out?

Apparently, in developing and in well-developed societies we are confronted with a crisis of academic medicine in all aspects: health care, teaching, and research. Health care providers in teaching hospitals are under pressure to generate revenues, academic research is pressed to keep pace with institutions devoted solely to research, and teaching is often understood not as privilege and honor but as burden and nuisance. The key problem and the principal cause of the crisis are low interest of the best young graduates to follow an academic career in a world where the benefits and values of the private sector are prevailing. Confronted with these circumstances and the continuous perils of permanent brain-drain, we developed an innovative concept of "shared employment' where two academic institutions (one in a developed and one in a developing country) will collaborate in development and support of fresh talents, building elite academic staff. Most academic exchange programs developed so far have proved to be ineffective and of poor vitality, in spite of loud exclamations, high expectations, and a huge amount of good will involved. In contrast, the suggested cooperation will be based exclusively on mutual interest and clearly defined benefits for all involved parties.     

Cat at home? Cat scratch disease with atypical presentations and aggressive radiological findings mimicking sarcoma,a potential diagnostic pitfall

Background and purpose — Cat scratch disease (CSD) is a self-limiting disease caused by Bartonella (B.) henselae. It is characterized by granulomatous infection, most frequently involving lymph nodes. However, it can present with atypical symptoms including musculoskeletal manifestations, posing a diagnostic challenge. We describe the prevalence and demographics of CSD cases referred to a sarcoma center, and describe the radiological, histological, and molecular findings.Patients and methods — Our cohort comprised 10 patients, median age 27 years (12–74) with clinical and radiological findings suspicious of sarcoma.Results — 7 cases involved the upper extremities, and 1 case each involved the axilla, groin, and knee. B. henselae was found in 6 cases tested using polymerase chain reaction and serology in 5 cases. 9 cases were soft tissue lesions and 1 lesion involved the bone. 1 patient had concomitant CSD with melanoma metastasis in enlarged axillary lymph nodes. On MRI, 5 soft tissue lesions were categorized as probably inflammatory. In 3 cases, with still detectable lymph node structure and absent or initial liquefaction, the differential diagnosis included lymph node metastasis. A sarcoma diagnosis was suggested in 4 cases. The MRI imaging features of the bone lesion were suspicious of a bone tumor or osteomyelitis.Interpretation — Atypical imaging findings cause a diagnostic challenge and the differential diagnosis includes malignant neoplasms (such as sarcoma or carcinoma metastasis) and other infections. The distinction between these possibilities is crucial for treatment and prognosis.

Bartonella (B.) henselae infection with regional lymphadenopathy may mimic neoplastic processes such as soft tissue or bone tumor, metastasis, or lymphoma, leading to a delayed diagnosis and unnecessary invasive procedures resulting in overtreatment (Huang et al. 1989, Gielen et al. 2003, Mazur-Melewska et al. 2015). The classical differentiation of CSD from soft tissue neoplasm are enlarged lymph node with preserved hilar architecture and reactive changes of the surrounding fat and fascia, suggesting inflammation (Wang et al. 2009, Mazur-Melewska et al. 2015, Bernard et al. 2016, Chen et al. 2018). In atypical CSD cases, soft tissue mass or a solitary bone lesion may mimic a sarcoma due to the overlapping clinical and radiological findings. Previous studies, analyzing B. henselae infections and their clinical and radiological presentation, are mainly focused on imaging features of lymphadenopathy/lymphadenitis at the epitrochlear region (Gielen et al. 2003, Bernard et al. 2016, Chen et al. 2018). However, the assessment regarding the potential differential diagnosis of sarcoma is scarce, as only single cases of atypical B.henselae infection mimicking sarcoma have been published so far (Frank et al. 1952, Nimityongskul et al. 1992, Fox and Gurtler 1993, Eichhorn-Sens et al. 2008, Colman et al. 2014, Dhal et al. 2020). To our knowledge, this retrospective study represents the first large case series of atypical CSD cases who were transferred to a sarcoma center with the primary diagnosis of sarcoma. The objectives of this study were (i) to describe the prevalence and demographics of atypical CSD cases in a musculoskeletal, orthopedic sarcoma center, (ii) to describe the radiological, histological, and molecular findings, (iii) to highlight the specific MRI criteria for differentiation, and (iv) to discuss differential diagnoses with the aim of raising awareness of this rare disease.     

Loss of heterozygosity and protein expression of APC gene in renal cell carcinomas

This study evaluated the potential contribution of the APC gene to malignant transformation in patients with renal cell carcinoma. We tested 36 human renal cell carcinoma samples and 18 adjacent normal kidney tissues for the expression of APC protein, both wild and truncated types, by western blot using antibodies that recognize either the carboxy or the amino epitope of the APC protein. The same tumor samples together with autologous peripheral blood were also analyzed at the DNA level. Using specific oligonucleotide primers for exons 11 and 15, gene instability was followed by polymerase chain reaction/loss of heterozygosity (LOH) (on the basis of restriction fragment length polymorphism). Molecular data were also compared to pathohistological diagnosis, TNM stage, and patient’s age using multivariate statistical methods. All normal renal tissues revealed expression of the wild-type APC protein. Neither wild nor mutant type proteins were found in 36% (13/36) of tumor samples; the rest of tumor tissues expressed the wild-type protein (312 kDa). Mutated APC protein, with a molecular weight of 117 kDa, was found in only one tumor sample. From 36 tumor samples 16 (44.4%) were informative for RsaI exon 11 polymorphic site, while only half of these (8/16) demonstrated LOH. From 13 tumor samples that had no detectable protein product by western blot analysis eight were homozygous for the exon 11 polymorphism and were tested for another polymorphic site, MspI/exon 15. The overall proportion of LOH cases for both polymorphisms tested was 52.9% (9/17). Pathohistological diagnosis and molecular data showed no correlation. However, multivariate analysis determined a stage strong positive correlation of age and TNM with the presence of LOH and the absence of the wild-type APC protein. Out results suggest that the APC tumor suppressor gene plays a role in renal carcinogenesis. Alterations in this gene are responsible for tumor evolution and progression, but cannot be considered as a first event in tumor initiation. Received: 20 May 1998 / Accepted: 23 November 1998     

Efficacy of Transvaginal Ultrasound Versus Magnetic Resonance Imaging for Preoperative Assessment of Myometrial Invasion in Patients with Endometrioid Endometrial Cancer: a Prospective Comparative Study

BackgroundWe compared the accuracy of preoperative transvaginal ultrasound (TVUS) versus magnetic resonance imaging (MRI) for the assessment of myometrial invasion (MI) in patients with endometrial cancer (EC), while definitive histopathological diagnosis served as a reference method.Patients and methodsStudy performed at a single tertiary centre from 2019 to 2021, included women with a histopathological proven EC, hospitalized for scheduled surgery. TVUS and MRI were performed prior to surgical staging for assessment MI, which was estimated using two objective TVUS methods (Gordon’s and Karlsson’s) and MRI. Patients were divided into two groups, after surgery and histopathological assessment of MI: superficial (≤ 50%) and deep (> 50%).ResultsSixty patients were eligible for the study. According to the reference method, there were 34 (56.7%) cases in the study with MI < 50%, and 26 (43.3%) with MI > 50%. Both objective TVUS methods and MRI showed no statistical significant differences in overall diagnostic performance for the preoperative assessment of MI. The concordance coefficient between both TVUS methods, MRI and histopathology was statistically significant (p < 0.001). Gordon’s method calculating MI reached a positive predictive value (PPV) of 83%, negative predictive value (NPV) of 83%, 77% sensitivity, 88% specificity, and 83% overall accuracy. Karlsson’s method reached PPV of 82%, NPV of 79%, 69% sensitivity, 88% specificity, and 80% overall accuracy. Accordingly, MRI calculating MI reached PPV of 83%, NPV of 97%, 97% sensitivity, 85% specificity, and 90% overall accuracy.ConclusionsWe found that objective TVUS assessment of myometrial invasion was performed with a diagnostic accuracy comparable to that of MRI in women with endometrial cancer.Key words: endometrial neoplasms, radiology, oncology, cancer staging     

Structural basis for substrate specificity of heteromeric transporters of neutral amino acids

Despite having similar structures, each member of the heteromeric amino acid transporter (HAT) family shows exquisite preference for the exchange of certain amino acids. Substrate specificity determines the physiological function of each HAT and their role in human diseases. However, HAT transport preference for some amino acids over others is not yet fully understood. Using cryo–electron microscopy of apo human LAT2/CD98hc and a multidisciplinary approach, we elucidate key molecular determinants governing neutral amino acid specificity in HATs. A few residues in the substrate-binding pocket determine substrate preference. Here, we describe mutations that interconvert the substrate profiles of LAT2/CD98hc, LAT1/CD98hc, and Asc1/CD98hc. In addition, a region far from the substrate-binding pocket critically influences the conformation of the substrate-binding site and substrate preference. This region accumulates mutations that alter substrate specificity and cause hearing loss and cataracts. Here, we uncover molecular mechanisms governing substrate specificity within the HAT family of neutral amino acid transporters and provide the structural bases for mutations in LAT2/CD98hc that alter substrate specificity and that are associated with several pathologies.

Amino acids play a central role in cellular metabolism. Dysregulation of both intra- and extracellular amino acid concentrations is associated with pathological conditions (1). Amino acid transfer across the plasma membrane is mediated by specific transporters that bind and transport these molecules from the extracellular medium into the cell or vice versa.Heteromeric amino acid transporters (HATs) are a family of amino acid transporters comprised by a heavy subunit and a light subunit, linked by a conserved disulfide bridge (2). Heavy subunits (SLC3 family) are ancillary proteins required for trafficking the holotransporter to the plasma membrane (2), whereas the light subunits (LATs; SLC7 family) transport amino acids and confer substrate specificity to the heterodimer (2). HATs are amino acid exchangers that harmonize amino acid concentrations at each side of the plasma membrane and as such they play a critical role in amino acid homeostasis (1, 3).The physiological relevance of HATs is highlighted by their role in cancer and several inherited diseases (4–8). HAT neutral amino acid transporters in particular are gaining momentum as several mutations linked to human diseases have recently been identified, and new physiological roles for this group of transporters have been uncovered using knockout mouse models (8–13). Several loss-of-function mutations in human LAT2/CD98hc (SLC7A8/SLC3A2) are associated with age-related hearing loss (ARHL) (9) and cataracts (10). Also, some coding variants are linked to an increased risk of autism spectrum disorder (14). In addition, hLAT2/CD98hc overexpression in pancreatic cancer cells sustains glutamine-dependent mTOR activation to promote glycolysis and chemoresistance (15). This observation thus points to hLAT2/CD98hc as a potential pharmacological target in this particular type of cancer. On the other hand, LAT1/CD98hc (SLC7A5/SLC3A2), which is also linked to cancer (4, 7), participates in brain development and autism spectrum disorder (12). Finally, Asc1/CD98hc (SLC7A10/SLC3A2) is considered a target to regulate glutamatergic neurotransmission in some cognitive disorders, such as schizophrenia (16, 17), and a relevant player in adipocyte lipid storage, obesity, and insulin resistance (18).Several atomic structures of HATs (19–24) and LATs (25) have recently been described, thus paving the way for the dissection of the molecular transport mechanisms. The substrate-binding site of LATs determined in complex with a substrate or competitive inhibitors shows a conserved design consisting of two unwound segments of transmembrane (TM) 1 and TM6, which contain residues that recognize the α-amino and carboxyl groups of the substrate (21–25). Each member of the HAT family displays a preference for transporting a certain set of substrates (2). LAT2/CD98hc, LAT1/CD98hc, and Asc1/CD98hc transport neutral amino acids but of different sizes. LAT1 is specialized in large neutral amino acids but it is inefficient for L-glutamine, and it does not transport small amino acids. LAT2 transports both large and small neutral amino acids, and it is highly efficient for L-glutamine. Finally, Asc1 mediates the preferential uptake of small neutral amino acids, including D-isomers, particularly D-serine (26–28).Despite recent advances in resolving the structure of several HATs, the molecular mechanisms explaining why each member of the family shows exquisite preference for certain substrates but not others are mostly unknown. Here, we addressed the structural bases of substrate specificity in the HAT family. To this end, we used cryo–electron microscopy (cryo-EM) to determine the structure of human LAT2/CD98hc in inward-facing open and apo conformation. We used this structure to study substrate-binding determinants by combining Protein Energy Landscape Exploration (PELE) and molecular dynamics (MD), together with mutational and functional studies. We reveal that a few residues present in the substrate-binding pocket and nearby regions determine substrate preference, and we demonstrate how the substrate preference of several HATs can be interconverted. In addition, a region located at a certain distance of the substrate cavity but whose structure critically influences the conformation of the substrate-binding site also regulates substrate preference. This region accumulates mutations associated with ARHL and cataracts that alter hLAT2 substrate specificity.Our work uncovers key structural determinants that govern, by different mechanisms, the differences in substrate specificity found within HAT members of neutral amino acid transporters. It also provides the structural bases for mutations in LAT2/CD98hc associated with deafness and cataracts.