Metastatic Lymph Node Detection on Ultrasound Images Using YOLOv7 in Patients with Head and Neck Squamous Cell Carcinoma

Ultrasonography is the preferred modality for detailed evaluation of enlarged lymph nodes (LNs) identified on computed tomography and/or magnetic resonance imaging, owing to its high spatial resolution. However, the diagnostic performance of ultrasonography depends on the examiner's expertise. To support the ultrasonographic diagnosis, we developed YOLOv7-based deep learning models for metastatic LN detection on ultrasonography and compared their detection performance with that of highly experienced radiologists and less experienced residents. We enrolled 462 B- and D-mode ultrasound images of 261 metastatic and 279 non-metastatic histopathologically confirmed LNs from 126 patients with head and neck squamous cell carcinoma. The YOLOv7-based B- and D-mode models were optimized using B- and D-mode training and validation images and their detection performance for metastatic LNs was evaluated using B- and D-mode testing images, respectively. The D-mode model's performance was comparable to that of radiologists and superior to that of residents' reading of D-mode images, whereas the B-mode model's performance was higher than that of residents but lower than that of radiologists on B-mode images. Thus, YOLOv7-based B- and D-mode models can assist less experienced residents in ultrasonographic diagnoses. The D-mode model could raise the diagnostic performance of residents to the same level as experienced radiologists.

Three Signs to Help Detect Sjögren's Syndrome: Incidental Findings on Magnetic Resonance Imaging and Computed Tomography

This study aimed to retrospectively investigate the prevalence of Sjögren's syndrome (SS) among patients with ranulas, parotid cysts, or parotid calcifications; identify the characteristic magnetic resonance imaging (MRI) or computed tomography (CT) findings of the lesions associated with SS; and compare the SS disease stages among SS patients with the three lesion types. A total of 228 patients with the lesions were classified into SS, possible SS, and non-SS groups. The prevalence of SS among patients with ranulas, parotid cysts, or parotid calcifications was 16%, 24%, and 40%, and the rates of either SS or possible SS were 25%, 41%, and 64%, respectively. SS was associated with (i) ranulas: ≤17 mm; (ii) parotid cysts: bilateral and multiple; and (iii) parotid calcifications: in females, bilateral, multiple, parenchymal, and no coexisting calcifications in other tissues. SS patients with ranulas were significantly younger and had lower submandibular gland stage scores on MRI/CT than those with other lesions. Additionally, in 58% and 15% of SS patients with ranulas and parotid calcifications, respectively, detection of the lesions led to the diagnosis of primary SS. Therefore, recognizing the prevalence of SS among patients with these lesions and the findings associated with SS can help detect undiagnosed SS.

Comparison of salivary gland MRI and ultrasonography findings among patients with Sjögren's syndrome over a wide age range

Objectives

This retrospective study compared MRI and US findings among patients with SS over a wide age range.

Methods

Ninety patients with SS aged 8–84 years who had undergone both MRI and US examinations were divided into four groups according to age, as follows: <18 years (juvenile SS, JSS), 9 patients; 18–39 years, 12 patients; 40–69 years, 53 patients; >69 years, 16 patients. Imaging findings of parotid glands (PGs) and submandibular glands (SMGs) were compared among the four groups. Furthermore, the relationships within and between imaging findings and various clinical findings were examined.

Results

On MRI, patients with JSS commonly exhibited multiple high-intensity spots in the PGs on MR sialography and fat-suppressed T2-weighted imaging. With increasing SS group age, the frequencies and numbers of the high-intensity spots were lower. Fat areas on MRI and hyperechoic bands on US were rarely observed in the PGs and SMGs of patients with JSS, whereas they were more common in patients with adult SS. In addition, the presence of hyperechoic bands on US, the presence of fat areas on MRI, and decreased salivary flow were associated with one another.

Conclusion

Salivary gland imaging findings in patients with JSS were characterized by punctate sialectasis, whereas those findings in patients with adult SS were characterized by fatty degeneration. Distinct findings in patients with JSS and adult SS are likely to reflect differences in glandular lesion stage. MRI and US are presumably useful for evaluation of glandular lesion severity during follow-up.

A case of periosteal fasciitis located in the mandible in a child

Periosteal fasciitis (PF), a subtype of nodular fasciitis, is an uncommon benign soft-tissue mass that originates from the periosteum or tissues adjacent to bones. PF has rarely seen in children, especially involving in the mandible. This case report presents a rare case of PF originating from the periosteum of the mandible in an 11-year-old girl. She was referred to our hospital with fast-growing painless swelling in her left mandible. Computed tomography revealed an exophytic juxtacortical mass eroding the lower part of the left mandible and lower mandibular cortex with a periosteal reaction. The mass showed low signal intensity on T1-weighted magnetic resonance imaging (MRI) and high signal intensity on T2-weighted MRI. The apparent diffusion coefficient (ADC) of the lesion found to be moderate. Dynamic contrast-enhanced MRI revealed a gradual increment pattern in the central region of the mass. On 18F-fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT), relatively high 18F-FDG uptake was observed on the early scan and the 18F-FDG uptake was declined on the delayed scan. The clinical and conventional radiological findings of the mass were suggestive of malignancy. However, the findings of ADC and dynamic MRI and dual-time-point FDG-PET/CT favored benign etiology over malignant etiology. Histological and immunohistochemical findings along with reactive ossification of the periosteum confirmed the diagnosis of PF. Currently, comprehensive examinations, such as clinical, imaging, and histopathological examinations, are recommended for the definitive diagnosis of PF, while MRI and dual-time-point FDG-PET/CT could have a potential usefulness to differentiate from malignancy.

Juvenile primary Sjögren's syndrome with ranula: is ranula a clinical sign that leads to early detection of Sjögren's syndrome?

Juvenile primary Sjögren’s syndrome (pSS) is rare. Although recurrent parotitis is reported to be the most common symptom of juvenile pSS, the clinical symptoms and features of the syndrome are not well understood and are poorly defined. Here we report a rare case of juvenile pSS in a patient with plunging ranula. The patient had no symptoms other than swelling of the oral floor and had no symptoms of parotitis. Magnetic resonance imaging (MRI) revealed the diagnosis of plunging ranula. In addition, the findings of the bilateral parotid glands on MRI and subsequent ultrasonography (US) strongly suggested SS. On the basis of these imaging findings and laboratory data, a pediatric rheumatologist confirmed the diagnosis of juvenile pSS. The ranula may be one clinical sign of SS. However, this association remains generally unknown. Hypothesizing that SS might cause ranula development, we retrospectively investigated cases of patients with ranula who underwent MRI at our hospital. We found that many of these patients (> 20%) had characteristic findings strongly suggestive of SS. This result suggests that SS-induced changes in the sublingual glands are one cause of ranula formation. We think that ranula is a sign of early-stage SS. Therefore, patients with ranulae, whether adults or children, should undergo careful assessment of not only the sublingual glands but also the parotid and submandibular glands with MRI and/or US to investigate possible SS. This assessment may lead to early detection of SS.

A case of tophaceous pseudogout of the temporomandibular joint extending into the cranium

A case of tophaceous pseudogout (i.e., calcium pyrophosphate dihydrate crystal deposition disease) in the temporomandibular joint (TMJ) extending into the cranium is reported. A 59-year-old woman was referred to hospital with swelling and pain in the left cheek, and with trismus. Computed tomography imaging revealed a large, granular, calcified mass surrounding the left condylar head, partly destroying the cortex of the condylar head, and extending into the cranium by destroying the glenoid fossa. Magnetic resonance imaging revealed that the soft-tissue mass was of low-signal intensity on T1- and T2-weighted images, and was enhanced after intravenous injection of gadolinium. The mass was clinically and radiographically suspected to be a neoplastic lesion or a synovial osteochodromatosis. However, histological analysis demonstrated that the mass contained granulomatous lesion due to multiple nodular deposits of numerous rod-shaped and rhomboid crystals, which verified the diagnosis of tophaceous pseudogout. The lesion was excised surgically using a preauricular approach. Neither radiographic nor clinical examination demonstrated any signs of mass recurrence in the long-term 8- and 14-year postoperative recall examinations. Tophaceous pseudogout is a rare benign arthropathy that presents with clinical and radiographic features mimicking neoplastic conditions of the TMJ. Therefore, it is recommended that tophaceous pseudogout is considered in the differential diagnosis when a calcified mass lesion of the TMJ is encountered.

Combined classification system based on ACR/EULAR and ultrasonographic scores for improving the diagnosis of Sjögren's syndrome

We retrospectively evaluated the effectiveness of combined use of salivary gland ultrasonography (US) and the 2016 American College of Rheumatology/European League Against Rheumatic Disease (ACR/EULAR) classification criteria for improving the diagnostic efficiency in patients with Sjögren’s syndrome (SS). A US-based salivary gland disease grading system was developed using a cohort comprising 213 SS or non-SS patients who fulfilled the minimum requirements for classifying SS based on the American-European Consensus Group (AECG) and ACR criteria. Using 62 SS or non-SS patients from the 213 patients and who had also undergone all the 5 examinations needed for the ACR/EULAR classification, we compared the diagnostic accuracy of various combinations of the ACR/EULAR and US classifications for diagnosing SS, using the clinical diagnosis of SS by rheumatologists as the gold standard. The ACR/EULAR criteria discriminated clinical SS patients with 77% and 79% accuracy for those with primary or secondary SS and for those with primary SS, respectively. However, the integrated score system of the ACR/EULAR and US classifications yielded 92% and 93% accuracy for these 2 SS patient groups, respectively, provided that US score of 3 was assigned to patients with US grade ≥2, and then patients with integrated threshold score of ≥5 were diagnosed as SS. Cross-validation also indicated improved accuracy of the integrated ACR/EULAR and US score system (91.9 and 93.0% for primary/secondary and primary SS patients, respectively) over that by the ACR/EULAR criteria alone. (74.2 and 86.0%, respectively). The integrated ACR/EULAR and US scoring system can improve the diagnosis of patients with clinical SS.

Multiparametric MR imaging of sinonasal diseases: time-signal intensity curve- and apparent diffusion coefficient-based differentiation between benign and malignant lesions

BACKGROUND AND PURPOSE

The sinonasal region is a platform for a broad spectrum of benign and malignant diseases, and image-based differentiation between benign and malignant diseases in this area is often difficult. Here, we evaluated multiparametric MR imaging with combined use of TICs and ADCs for the differentiation between benign and malignant sinonasal tumors and tumorlike diseases.

MATERIALS AND METHODS

TICs obtained from dynamic contrast-enhanced MR imaging and ADCs were analyzed on a lesion-by-lesion (overall TIC and ADC) and pixel-by-pixel (TIC and ADC mapping) basis in patients with benign (n = 21) or malignant (n = 23) sinonasal tumors and tumorlike diseases. The TICs were semiautomatically classified into 5 distinctive patterns (flat, slow uptake, rapid uptake with low washout ratio, rapid uptake with high washout ratio, and miscellaneous). ADCs were determined by using b-values of 500 and 1000 s/mm(2).

RESULTS

Malignant sinonasal tumors had small (<25%) areas of the type 1 flat TIC profile as determined by pixel-by-pixel TIC analysis and large (≥50%) areas of low or extremely low ADCs (≤1.2 × 10(-3) mm(2/)s) as determined by ADC mapping. Consequently, stepwise classification on the basis of TICs and ADCs successfully (at 100% accuracy) discriminated malignant from benign sinonasal diseases in the present patient cohort.

CONCLUSIONS

Multiparametric MR imaging by using TICs and ADCs may help differentiate benign and malignant sinonasal diseases.

Apparent diffusion coefficient mapping for sinonasal diseases: differentiation of benign and malignant lesions

BACKGROUND AND PURPOSE

CT and MR imaging features of benign and malignant sinonasal lesions are often nonspecific. Therefore, we evaluated the ADC-based differentiation of these lesions.

MATERIALS AND METHODS

We retrospectively assessed ADCs of 61 patients with histologically proved sinonasal tumors and tumorlike lesions: 19 benign lesions, 28 malignant tumors, and 14 inflammatory lesions. Overall ADCs and percentages of total tumor area with extremely low, low, intermediate, or high ADCs (ADC mapping) were determined by using 2 b-values (500 and 1000 s/mm(2)).

RESULTS

ADCs of malignant tumors (0.87 ± 0.32 × 10(-3) mm(2)/s) were significantly lower than those of benign (1.35 ± 0.29 × 10(-3) mm(2)/s, P < .0001) and inflammatory (1.50 ± 0.50 × 10(-3) mm(2)/s, P = .0002) lesions. On ADC mapping, percentages of total tumor area within malignant tumors having extremely low or low ADCs were significantly (P < .0001) greater than those within benign and inflammatory lesions. Cutoff points for ADC mapping (≥78% of tumor areas having extremely low or low ADCs) effectively differentiated benign or inflammatory lesions and malignant tumors with 75% sensitivity, 94% specificity, 85% accuracy, and 91% positive and 82% negative predictive values, respectively. ADCs also effectively discriminated lymphomas and SCCs from other malignant tumors.

CONCLUSIONS

ADC mapping may be an effective MR imaging tool for the differentiation of benign/inflammatory lesions from malignant tumors in the sinonasal area.

Multiparametric magnetic resonance imaging for the differentiation between benign and malignant salivary gland tumors

PURPOSE

To evaluate the stepwise approach in differentiating between benign and malignant salivary gland tumors using time-intensity curves (TICs) and apparent diffusion coefficients (ADCs).

MATERIALS AND METHODS

TICs and ADCs were analyzed on the tumor-by-tumor (overall) and pixel-by-pixel (TIC and ADC maps) bases in patients with benign (n = 52) or malignant (n = 18) salivary gland tumor. TICs were categorized into Types 1 (<20% increment ratio), 2 (>or=20% increment ratio and >120 sec peak time), 3 (>or=20% increment ratio, <or=120 sec peak time, and <30% washout ratio), or 4 (>or=20% increment ratio, <or=120 sec peak time, and >or=30% washout ratio). ADCs were classified as extremely low (<0.6 x 10(-3) mm(2)/sec), low (<1.2), intermediate (<1.8), or high (>or=1.8).

RESULTS

Malignant tumors had small (<30%) areas with Type 1 TIC with one of the following magnetic resonance imaging (MRI) characteristics: Type 3 overall TIC patterns, Type 4 overall TIC patterns and extremely low (<0.60 x 10(-3) mm(2)/sec) overall ADCs, or Type 2 overall TIC patterns and large (>40%) areas with low or extremely low ADCs.

CONCLUSION

We propose a stepwise approach by using multiparametric MRI techniques as an effective tool for differentiating between benign and malignant salivary gland tumors.

MR factor analysis: improved technology for the assessment of 2D dynamic structures of benign and malignant salivary gland tumors

PURPOSE

To establish an MR factor analysis technique for two-dimensional (2D) MR dynamic structures of benign and malignant salivary gland tumors.

MATERIALS AND METHODS

Dynamic contrast-enhanced MRI using a surface coil was performed on 36 patients with benign (N = 24) or malignant (N = 12) salivary gland tumors. Signal intensity kinetics in each pixel of the tumors after contrast medium injections were semiautomatically categorized into four patterns (slow uptake, rapid uptake with high washout, rapid uptake with low washout, and flat). The 2D distributions of the kinetic patterns in the tumors were compared with the histological features of the corresponding parts of the excised tumors and with overall kinetics obtained by a conventional analysis.

RESULTS

The MR factor analysis technique allowed the pixel-to-pixel evaluation of the contrast enhancement kinetics of the salivary gland tumors. The 2D distributions of the time-intensity curve (TIC) patterns correlated well with the histological features of the salivary gland tumors and allowed more detailed dynamic structures of the tumors compared with the results obtained by the conventional dynamic study analysis.

CONCLUSION

The proposed MR factor analysis would be clinically feasible to diagnose salivary gland tumors and tumor-like lesions.

Apparent diffusion coefficient mapping of salivary gland tumors: prediction of the benignancy and malignancy

BACKGROUND AND PURPOSE

Preoperative prediction of tumor malignancy is clinically very important, because this information strongly influences the surgical plan. We evaluate the preoperative apparent diffusion coefficient (ADC) maps of benign and malignant salivary gland tumors.

MATERIALS AND METHODS

High-resolution MR imaging was performed on 31 patients with benign or malignant salivary gland tumors; ADC maps of the tumors were also obtained. Surface coils of 47 or 110 mm diameter were used to improve the image resolution. The ADCs were compared with histologic features of the excised tumors.

RESULTS

The ADC maps effectively depicted the histologic features of the salivary gland tumors, such as presence of cancer cells, myxomatous tissues, fibrosis, necrosis, cyst formation, and lymphoid tissues. The ADC maps showed that more frequent areas with high ADCs (> or = 1.8 x 10(-3) mm(2)/s) were significantly greater in benign tumors than in malignant tumors. The sensitivity and specificity for high ADC occupying fewer than 5% of the area of a tumor was 89% and 100%, respectively, resulting in 97% accuracy, 100% positive predictive value, and 96% negative predictive value.

CONCLUSION

The ADC may provide preoperative tissue characterization of the salivary gland tumors.

Parotid tumors: differentiation of benign and malignant tumors with quantitative sonographic analyses

We asked in this study if the quantitative sonographic analysis could diagnose effectively the benign and malignant tumors of the parotid gland. Sonographic analyses using mean grey values and SDs of echo levels were performed on the 21 benign tumors and 22 malignant tumors of the parotid glands. Both the mean grey level and the SD of the echo levels were significantly and characteristically different among the different parotid tumor groups. Discrimination analysis showed that, compared with single uses, a combined use of these two criteria improved diagnostic accuracy to 81% (carcinoma vs. pleomorphic adenomas), 93% (malignant lymphomas vs. pleomorphic adenomas), 91% (carcinomas vs. malignant lymphomas), 100% (pleomorphic adenomas vs. Warthin's tumors), 100% (carcinomas vs. Warthin's tumors) and 100% (malignant lymphomas vs. Warthin's tumors). These findings suggest that quantitative sonographic analysis is effective in differentiating benign and malignant tumors of the parotid gland.

Combination of helical CT and Doppler sonography in the follow-up of patients with clinical N0 stage neck disease and oral cancer

BACKGROUND AND PURPOSE

Correctly diagnosing metastatic nodes is important for the follow-up of patients with clinical N0 stage neck disease and oral cancer. A combination of helical CT and Doppler sonography may facilitate the accurate detection of lymph node metastasis in patients with clinical N0 stage neck disease.

METHODS

A combination of contrast-enhanced helical CT and Doppler sonography was performed to monitor the necks of 58 patients with initial clinical N0 stage neck disease. Of these patients, 17 underwent surgery; nodal metastasis in the neck was histopathologically confirmed. A node was diagnosed as metastatic if it fulfilled the CT criteria for metastatic nodes (short-axis diameter equal to or greater than the cutoff points for each level of the neck or central nodal necrosis) and if, additionally, it did not exhibit sonographic features for nonmetastatic nodes (normal hilar echogenicity and hilar flows). The presence of metastasis was confirmed histopathologically.

RESULTS

During the follow-up periods, metastatic nodes were histologically confirmed in 17 (29%) patients. Of 30 metastatic nodes from the 17 patients with metastatic nodes, 22 (73%) appeared within the first year and 28 (93%) within the first 2 years; 20 developed from nonmetastatic nodes, and 10 were newly detectable. The combined criteria were effective in revealing 26 (87%) nodes, yielding 87% sensitivity, 100% specificity, and 100% positive and 99% negative predictive values. The independent use of one of these techniques alone resulted in low (67%) or moderate (87%) positive predictive values for sonography and CT, respectively. Seven hundred forty-one (97%) of 761 nodes that were nonmetastatic at initial examination remained nonmetastatic (737 nodes) or had disappeared (four nodes). As a result, a combination of CT and sonography was effective in revealing all 17 cases of metastatic nodes.

CONCLUSION

A combination of contrast-enhanced helical CT and Doppler sonography is useful for the follow-up study of clinical N0 stage neck disease.

Contribution of doppler sonography blood flow information to the diagnosis of metastatic cervical nodes in patients with head and neck cancer: assessment in relation to anatomic levels of the neck

BACKGROUND AND PURPOSE

Although sonographic evaluation of cervical adenopathy by use of size criteria is effective, the sensitivity and specificity fall short of that required to make adequate judgments regarding neck dissection. Therefore, we tested whether the combined use of size criteria and Doppler sonographic findings would improve the predictive ability for metastatic cervical nodes.

METHODS

We analyzed 338 histologically proved cervical lymph nodes (108 metastatic and 230 nonmetastatic) in 73 patients with head and neck cancer. The sonographic topography of the nodes was compared with dissected specimens, and their position in the neck was categorized into three levels (I, II, and III+IV). The diagnostic accuracy of sonography was evaluated by using the single criterion of short-axis diameter of the node or by the combined criteria of short-axis diameter and Doppler blood flow features (the absence or presence of normal hilar flow).

RESULTS

As compared with the single criterion of short-axis nodal diameter, the combined criteria of nodal size and Doppler blood flow patterns increased the diagnostic accuracy of sonography at all levels in the neck. Accordingly, the best cut-off values were improved to 6, 7, and 5 mm for nodes at levels I, II, and III+IV, respectively. In addition, the combined criteria yielded high sensitivites (> or = 89%) and specificities (> or = 94%).

CONCLUSION

Hilar blood flow information obtained by Doppler sonography significantly improves diagnostic accuracy for the detection of nodes metastatic from head and neck squamous cell carcinoma.

Immunological characteristics of a synthetic peptide associated with a catalytic domain of mutans streptococcal glucosyltransferase

The immunogenicity of a multiple antigenic peptide construct consisting of four copies of the synthetic 21-mer peptide DANFDSIRVDAVDNVDADLLQ was measured. The composition of this peptide was derived from a sequence in the N-terminal region of mutans streptococcal glucosyltransferases (GTFs) containing an aspartic acid implicated in catalysis. The peptide (CAT) construct was synthesized as a tetramer on a lysine backbone and subcutaneously injected into Sprague-Dawley rats for polyclonal antibody formation or intraperitoneally injected into BALB/c mice, and then spleen cell fused with Sp2/0Ag14 murine myeloma cells for monoclonal antibody formation. The resulting rat antisera and mouse monoclonal antibodies reacted with CAT and with native GTF isozymes from Streptococcus sobrinus and Streptococcus mutans (in enzyme-linked immunosorbent assay and Western blot [immunoblot] analyses). Functional inhibition of the water-insoluble glucan synthetic activity of S. sobrinus GTF-I was demonstrated with an immunoglobulin M anti-CAT monoclonal antibody (> 80% inhibited) and with rat sera (approximately 17% inhibited). The monoclonal antibody preparation also modestly inhibited the water-soluble glucan synthetic activity of an S. mutans GTF mixture. These results suggest that the CAT peptide contains B-cell epitopes that are similar to those of intact mutans streptococcal GTFs and has the potential to elicit antibody that can inhibit GTF function. Thus, sequences within this peptide construct may have value for inclusion in a synthetic dental caries vaccine.

Plasmodium falciparum sexual stage antigens: immunogenicity and cell-mediated responses

Antibody and cell-mediated immune responses to the transmission-blocking target antigens of Plasmodium falciparum, Pfs 48/45, were determined in infected non-immune patients and in immune individuals from an endemic area. Characterization of the B cell epitopes with monoclonal antibodies showed that there were five regions identifiable but there could be interactions between them causing either competitive or enhancing effects. Sera from infected non-immune patients contained antibodies that would compete with one or more of the mAbs to the different epitopes. Immune responsiveness to purified Pfs 48/45 in P. falciparum-immune adults measured as lymphoproliferation, production of interferon-gamma, or as Pfs 48/45-specific antibody was very limited. This did not appear to be due to MHC class II restriction, to diversity in structure of the parasite antigens or to a failure of immunological memory. The antibody-response data were more consistent with down-regulation of immunity as a result of prolonged exposure to infection.

Cellular and humoral immune responses to Plasmodium falciparum gametocyte antigens in malaria-immune individuals. Limited response to the 48/45-kilodalton surface antigen does not appear to be due to MHC restriction

We have examined immune responses to a cultured Plasmodium falciparum gametocyte lysate and to an affinity-purified preparation of the 48/45-kDa gamete surface Ag in a group of 30 malaria immune individuals and in 24 Europeans with no previous exposure to malaria. Cellular responses were assessed in vitro by lymphoproliferation and production of IFN-gamma; antigamete antibodies were detected by immunofluorescence, Western blotting, and competitive ELISA. Cells from all the malaria immune donors responded to the gametocyte lysate in both assays while cells from nonimmune donors gave only weak proliferative responses. Antigamete antibodies were detected in the serum of all the immune donors but not in serum from nonimmunes. Nonimmune donors were completely unresponsive to the purified 48/45-kDa surface Ag while cells from 40% of immune donors responded by either proliferation or IFN-gamma production. Only 3 of 30 immune donors had detectable antibodies to the 48/45-kDa Ag. Class II HLA type was determined for 27 of the immune donors but no relationship between HLA-DR or -DQ and responsiveness to the 48/45-kDa Ag was discerned. The possible reasons for limited recognition of this gamete surface Ag are discussed.

Cellular and humoral immune responses to Plasmodium falciparum gametocyte antigens in malaria-immune individuals. Limited response to the 48/45-kilodalton surface antigen does not appear to be due to MHC restriction

We have examined immune responses to a cultured Plasmodium falciparum gametocyte lysate and to an affinity-purified preparation of the 48/45-kDa gamete surface Ag in a group of 30 malaria immune individuals and in 24 Europeans with no previous exposure to malaria. Cellular responses were assessed in vitro by lymphoproliferation and production of IFN-gamma; antigamete antibodies were detected by immunofluorescence, Western blotting, and competitive ELISA. Cells from all the malaria immune donors responded to the gametocyte lysate in both assays while cells from nonimmune donors gave only weak proliferative responses. Antigamete antibodies were detected in the serum of all the immune donors but not in serum from nonimmunes. Nonimmune donors were completely unresponsive to the purified 48/45-kDa surface Ag while cells from 40% of immune donors responded by either proliferation or IFN-gamma production. Only 3 of 30 immune donors had detectable antibodies to the 48/45-kDa Ag. Class II HLA type was determined for 27 of the immune donors but no relationship between HLA-DR or -DQ and responsiveness to the 48/45-kDa Ag was discerned. The possible reasons for limited recognition of this gamete surface Ag are discussed.

High frequency of antibody response to Plasmodium falciparum gametocyte antigens during acute malaria infections in Papua New Guinea highlanders

Sera from 62 adult Papua New Guinea highlanders with suspected acute malaria were tested by competitive ELISA for the presence of antibodies capable of inhibiting binding of 8 monoclonal antibodies (Mabs) directed against epitopes on gametocytes of Plasmodium falciparum. Between 33% and 72% of the malaria cases were inhibitory, depending on the Mab. There was no difference between the proportion of persons with P. falciparum (asexuals or gametocytes) and P. vivax whose sera inhibited Mab binding, but all 3 categories had a significantly higher proportion of inhibitors than persons who were malaria negative. The amount of gametocyte antibody recognizing epitopes on Pfs 48/45 and Pfs 230 increased with increasing numbers of previous malaria episodes. The proportion of sera from these relatively nonimmune adults which had gamete antibodies was similar to the proportion seen in sera from a highly endemic area, suggesting that antibody responses to these epitopes are a part of the initial response observed after a limited number of malaria episodes.

Malaria in adult outpatients at Goroka Hospital during 1986

Of 206 adult outpatients attending Goroka Hospital with suspected malaria during 1986, 40.3% had blood slides positive for malaria (28.2% Plasmodium falciparum, 13.6% P. vivax and 1.9% P. malariae). Parasite densities and proportions of cases with gametocytes were higher than observed in endemic regions. Acquisition of infection during recent coastal travel was implicated in the majority of cases (86%). 6 out of 13 gametocyte carriers tested were infectious to Anopheles farauti mosquitos. Anti-malaria ELISA values in sera were elevated above non-immune values in over 75% of infections, although ELISA values were low compared to those in sera from residents of coastal areas, indicating the low level of previous exposure to malaria.

Isolation and characterization of proteinases from the sarcocarp of snake-gourd fruit

Seven proteinases were isolated from the fruit of snake-gourd, Trichosanthes cucumeroides Maxim. Their isozymes are all serine proteinases, and homologous in their respective molecular weights, amino acid compositions, and enzymatic properties. Their molecular weight was estimated to be about 50,000. Using casein as a substrate, the maximum activity was found in the alkaline pH region. The optimum temperature using casein was 70 degrees C at pH 7.3. The enzymes were strongly inhibited by diisopropyl fluorophosphate and not inhibited by inhibitors of sulfhydryl or metalloproteases. The reduced and S-carboxymethylated insulin B-chain was used as a substrate in an investigation of the specificity. The enzyme was found to have a wide specificity for this substrate but preferentially hydrolyzed the peptide bonds involving the carboxyl groups of charged amino acid such as S-cm-cysteine, glutamic acid, histidine, arginine, and lysine. Experimental evidence indicated that the snake-gourd proteinases are similar in their properties to cucumisin, which is isolated from the sarcocarp of melon fruit.