Distant Manifestations Research Articles

Umm Kamel’s Affair

Weakened by the expansion of several imperial and colonial projects, the inhabitants of Jabal ‘Amil survived as second-class citizens, severed from the urban expression of Lebanese nationalism, and having to formulate their identity amid countless transgressions on their scholarship and literary production. It is thus in the spectacles of the universe and the mysteries of the cosmos that they inscribed fragments of their oral legacy, turning the night sky into an archive that no empire could burn or colonize. And yet it is light pollution, leaking from the same cities they were once forced to nourish, that quickly established itself as the main transgressor, clearing the faintest stories in their celestial library. Although distant manifestations of Islamic cosmology could no longer animate their rural nights, new alterations in the sky after dark, no matter how violent, have proven worthy carri-ers of their modern myths and legends. And it is onto the loudest object in their polluted sky, the Israeli reconnaissance drone IAI Searcher MK, that they grafted the tale of their legendary matriarch Umm Kamel. I argue that Umm Kamel’s physical and symbolic ascent into the sky was orchestrated by a modern generation of ‘Amilis whose infidelity to the celestial stories authored by their ancestors fortified their ability to transform the combined pressures of pollution and colonization. United by their efforts to forge new imaginaries around a starless night, they invite reflection on the possibility (and responsibility) of confronting the sky we have together inherited rather than lamenting the one we have lost. In tracing Umm Kamel’s transformation from figure to constellation, I contend that their cosmic interventions set the stage for new alliances between design and darkness, and ultimately, for a more expanded imagination of night design, particularly within the context of the climate crisis.

Association between Helicobacter pylori Infection and Nasal Polyps: A Systematic Review and Meta-Analysis.

Helicobacter pylori (H. pylori) has definite or possible associations with multiple local and distant manifestations. H. pylori has been isolated from multiple sites throughout the body, including the nose. Clinical non-randomized studies with H. pylori report discrepant data regarding the association between H. pylori infection and nasal polyps. The aim of this first systematic review and meta-analysis was the assessment of the strength of the association between H. pylori infection and incidence of nasal polyps. We performed an electronic search in the three major medical databases, namely PubMed, EMBASE and Cochrane, to extract and analyze data as per PRISMA guidelines. Out of 57 articles, 12 studies were graded as good quality for analysis. Male-to-female ratio was 2:1, and age ranged between 17-78 years. The cumulative pooled rate of H. pylori infection in the nasal polyp group was 32.3% (controls 17.8%). The comparison between the two groups revealed a more significant incidence of H. pylori infection among the nasal polyp group (OR 4.12), though with high heterogeneity I2 = 66%. Subgroup analysis demonstrated that in European studies, the prevalence of H. pylori infection among the nasal polyp group was significantly higher than in controls, yielding null heterogeneity. Subgroup analysis based on immunohistochemistry resulted in null heterogeneity with preserving a statistically significant difference in H. pylori infection prevalence between the groups. The present study revealed a positive association between H. pylori infection and nasal polyps.

Update on headaches associated with physical exertion.

Headaches associated with physical exertion include headache precipitated by coughing or other Valsalva maneuvers, headache brought on by prolonged physical exercise, sexual headaches and cardiac cephalalgia. To review and update the clinical characteristics, etiologies, pathophysiology and management of these headaches related to exertion. In depth review of the publications, both in PubMed and in the main textbooks, of the different headaches induced by physical exercise. Cough, exercise and sexual headaches can be primary or secondary; therefore, complementary studies are mandatory to rule out structural lesions. However, clinical characteristics, such as an old age and response to indomethacin for cough headache or being a young male and response to beta-blockers for exercise and sexual headaches, plus a normal examination are suggestive of a primary etiology. Etiology for secondary varieties, as posterior fossa lesions for cough headache or vascular malformations for exercise and sexual headaches, are also different. Finally, headache as a distant manifestation of myocardial ischemia, also known as "cardiac cephalalgia", appears at exertion in around two-thirds of cases and typically lasts less than 30 minutes and is relieved by nitroglycerine. Primary and secondary cough headache can usually be suspected based on clinical characteristics and separated from exercise and sexual headaches, which share many aspects. Cardiac cephalalgia is not necessarily an exertional headache and should be considered in adult patients with short lasting headaches and patent vascular risk factors.

Acantosis nigricans intraoral y su relevancia clínica como manifestación de un síndrome paraneoplásico: Reporte de un caso

Malignant-or-paraneoplastic acanthosis nigricans is a verrucous and hyperpigmented tumor affecting the mucosa and skin. In most cases malignant acanthosis nigricans is a distant manifestation of an intra-abdominal primary cancer. While the diagnosis of malignant acanthosis nigricans is challenging, some specific clinical and histopathological findings could lead to an accurate diagnosis. A rare clinical case of a 59-year-old female, who was referred to the maxillofacial surgery service due to a painful oral lesion in the palatine region, is presented. Upon examination, papillomatous lesions were observed on the hard palate, that were later diagnosed as intraoral malignant acanthosis nigricans secondary to gastric cancer. Both local and systemic evaluations are discussed, highlighting the relevance of a multidisciplinary approach consistent with the fact that these manifestations, although infrequent, should generate suspicion among clinicians and therefore motivation to perform a diligent and complete study since it can reveal the presence of a malignant pathology.

Prevention of premature birth in pregnant women with vaginal candidiasis

Candida vulvovaginitis is an infectious lesion of the vulvar and vaginal mucosa caused by Candida yeast fungi. Vaginal candidiasis during pregnancy is associated with spontaneous miscarriages, premature rupture of the fetal membranes, premature birth, and low birth weight babies. Considering the potential risk of premature delivery at fungal invasion at the level of the lower reproductive tract of a pregnant woman, the search for a complex of preventive measures and timely treatment of сandida vulvovaginitis during gestation is of particular interest. The article presents the results of the use of the drug Zalain in 36 pregnant women, with a gestation period of 28 weeks or more with acute candidal vulvaginitis. In the course of the work, the results of local therapy with Zalain were evaluated and its clinical efficacy in the prevention of preterm labor was confirmed. The results of treatment contribute to a significant reduction in the frequency of initiation of preterm labor, as well as a persistent effect for 2-4 weeks after completion of the course in the postpartum period and the absence of early and distant manifestations of candidiasis in newborns.

Spectrum of Chronic Complications Related to Silicone Leakage and Migration

BackgroundMedical silicone is widely used as implants and free injections, but the spectrum of complications related to migration or embolization of silicone remains unclear. MethodsWe retrospectively reviewed 79 patients with silicone migration as confirmed on pathology between January 1, 2001, and December 31, 2016. The presenting clinical and imaging features, diagnostic testing, treatment, and outcome were assessed. ResultsNearly all patients were women, and 43% had a history of breast cancer. Sixty-three cases (80%) consisted of localized silicone granulomas, including 1 patient who developed severe hypercalcemia related to the granulomatous reaction. The remaining 16 cases (20%) involved migration of silicone to regional lymph nodes or distant tissue and included 1 case of chronic silicone pneumonitis. These complications were detected many years (median, 22 years; range, 1-40 years) after initial silicone placement. Only magnetic resonance imaging, dual-energy computed tomography (CT), and ultrasonography demonstrated specificity for detection of silicone in lymph nodes and soft tissues. Other modalities including positron emission tomography, single-energy CT, and mammography detected only nonspecific abnormalities. Excisional biopsy of symptomatic lymphadenopathy or masses usually led to resolution of symptoms. The patient with silicone pneumonitis improved with corticosteroid therapy. ConclusionsChronic complications related to silicone extravasation and migration can present with local or distant manifestations, typically encountered many years after the original silicone placement. Magnetic resonance imaging, dual-energy CT, and ultrasonography are helpful for noninvasive diagnosis.

Tumour-induced osteomalacia: An emergent paraneoplastic syndrome

Endocrine paraneoplastic syndromes are distant manifestations of some tumours. An uncommon but increasingly reported form is tumour-induced osteomalacia, a hypophosphatemic disorder associated to fibroblast growth factor 23 (FGF-23) secretion by tumours. The main biochemical manifestations of this disorder include hypophosphatemia, inappropriately low or normal tubular reabsorption of phosphate, low serum calcitriol levels, increased serum alkaline phosphatase levels, and elevated or normal serum FGF-23 levels. These tumours, usually small, benign, slow growing and difficult to discover, are mainly localized in soft tissues of the limbs. Histologically, phosphaturic mesenchymal tumours of the mixed connective tissue type are most common. Various imaging techniques have been suggested with variable results. Treatment of choice is total surgical resection of the tumour. Medical treatment includes oral phosphorus and calcitriol supplements, octreotide, cinacalcet, and monoclonal antibodies.

Osteomalacia tumoral: un síndrome paraneoplásico emergente

Endocrine paraneoplastic syndromes are distant manifestations of some tumours. An uncommon but increasingly reported form is tumour-induced osteomalacia, a hypophosphatemic disorder associated to fibroblast growth factor23 (FGF-23) secretion by tumours. The main biochemical manifestations of this disorder include hypophosphatemia, inappropriately low or normal tubular reabsorption of phosphate, low serum calcitriol levels, increased serum alkaline phosphatase levels, and elevated or normal serum FGF-23 levels. These tumours, usually small, benign, slow growing and difficult to discover, are mainly localized in soft tissues of the limbs. Histologically, phosphaturic mesenchymal tumours of the mixed connective tissue type are most common. Various imaging techniques have been suggested with variable results. Treatment of choice is total surgical resection of the tumour. Medical treatment includes oral phosphorus and calcitriol supplements, octreotide, cinacalcet, and monoclonal antibodies.

Invasive Fusobacterium necrophorum infections and Lemièrre's syndrome: the role of thrombophilia and EBV.

The purpose of this investigation was to describe the clinical spectrum of invasive Fusobacterium necrophorum infections and Lemièrre's syndrome, to examine the role of underlying thrombophilia and concomitant mononucleosis in Lemièrre's syndrome, and to describe thromboembolic complications. Patients with invasive F. necrophorum infections were identified either prospectively or retrospectively through the regional database of clinical microbiology from 2000 to 2015. Patient records were reviewed and blood samples from patients with Lemièrre's syndrome were collected for Epstein-Barr virus (EBV) serology and screening for thrombophilia. Of the 65 patients included, 33 had Lemièrre's syndrome. Of the remaining 32 patients, other infections of the respiratory tract and abdominal or urogenital infections were most common. Patients with Lemièrre's syndrome or other tonsillar infections were younger than patients from the other groups. For Lemièrre's syndrome, the 26 patients with severe sepsis on admittance had longer duration of symptoms. Three of five patients who developed distant manifestations had more than 14days of symptoms. Jugular vein thrombosis was verified in 14 patients, two of whom developed serious complications. Three of 26 patients tested had factor V Leiden mutation, corresponding to the background prevalence. One of 22 patients tested had a concomitant EBV infection. This study confirms earlier studies of the clinical spectrum caused by F. necrophorum. For Lemièrre's syndrome, the study adds to the knowledge on thromboembolic outcome, demonstrating that jugular vein thrombosis may cause severe complications. The time to treatment seems to be important for the risk of severe disease. In this study, concomitant EBV infection or underlying thrombophilia was uncommon.

The pain could be the sign of a serious pathology

Multiple myeloma is a malignancy of the plasmocytes that infiltrate the bone marrow, causing distant manifestations such as kidney failure and hypercalcemia. It presents mainly as anemia or bone pain with pathologic fractures. Myeloma can be managed with corticosteroids, thalidomide or chemotherapy, but the prognosis is, even with treatment, not so good. Back pain is one of the most frequent complains that brings patients to the hospital. It generally presents as musculoskeletal cause that can be easily managed with antinflamatory drugs, but sometimes lumbar pain is a warning sign of more serious pathology.

Acute uriticaria‐like lesions in allergen‐unexposed cutaneous tissues in a mouse model of late allergic rhinitis

The mechanisms of distant manifestation after a local allergic reaction are largely unknown. This study examined the development of cutaneous lesions in a mouse model of late allergic rhinitis (LAR). BALB/c mice were sensitized by ovalbumin (OVA) intraperitoneally two times (on days 0 and 10) and challenged by OVA intranasally on day 14. Four days after OVA challenge, nasal and cutaneous lesions including helper T (Th) responses, expression of adhesion molecules and presence of OVA and IgE were examined, and compared with unsensitized and unchallenged (control) mice. Compared with the control group, the LAR group developed LAR characterized by infiltration of lymphocytes and eosinophils, increased IgE values and increased productions of IL-4 and IL-5, but not IFN-gamma. A dominant infiltration of eosinophils and increase in mast cells, attachment of eosinophils to endothelium, intense expression of VCAM-1 on endothelium in venules and VLA-4 expression on eosinophils and mast cells were recognized in the cutaneous tissues. There were no differences in the expression of ICAM-1 on vascular endothelium and LFA-1 on infiltrated leucocytes between the two groups. CLA expression on lymphocytes was not detected, and the binding of OVA and IgE on mast cells and eosinophils was found in the cutaneous lesions in the LAR group, but not in the control group. This study suggests that acute urticaria[corrected]-like lesions in OVA-unexposed cutaneous tissues may be induced by immediate allergic reaction due to the systemic development of Th2-type response in a mouse model of LAR.

Delayed Immune-Mediated Adverse Effects of Polyalkylimide Dermal Fillers

To evaluate the clinical complaints, laboratory data, treatment, and follow-up of patients with delayed adverse effects related to polyalkylimide implants (PAIs). Prospective case series of patients injected with PAIs. A university tertiary teaching hospital. A prospectively acquired series of 25 patients with severe and/or persistent delayed adverse effects after PAI injection. The patients underwent clinical follow-up, a battery of blood tests, and when possible, biopsy and chest radiography. Clinical evaluation of granulomas, skin manifestations, and other local and systemic immune-mediated disorders possibly related to PAIs. The average latency period for onset of symptoms was 13.4 months. Eight patients were previously injected with another implant. Tender inflammatory nodules were seen in 24 patients. Systemic or distant manifestations appeared in 6 cases. Laboratory abnormalities were found in 20 cases. After an average of 21.3 months of follow-up, 11 patients appeared to be free of adverse effects, and 10 still had recurrent bouts. Although infrequent, delayed and recurrent chronic inflammatory and granulomatous reactions may complicate PAI fillers.

Local and distant manifestations of the venoarteriolar reflex

The venoarteriolar reflex (VAR) is considered a good example of local vasomotor control depending on both myogenic and neural mechanisms. The presence of a neural component suggests generalized effects in‐so‐far as the sensory input may reach systemic vasomotor regulatory centers. The objective of the present study was to find out whether such distant effects are really present. In order to do this we compared the changes in the blood flow of the contralateral arm while inducing the VAR in the ipsilateral one. The VAR was elicited by a local orthostatic stress – lowering of the ipsilateral arm 40 cm below heart level. During the procedure the subject was in supine position with the other arm at heart level. Index finger photoplethysmography from both arms was simultaneously recorded before, during, and after the orthostatic stimulation using PPG100C transducer coupled to a TSD200 amplifier (Biopac Systems Inc.). Precordial single channel ECG was also recorded. The VAR was evaluated by the changes in the amplitude of the photoplethysmography.The results showed the existence of contralateral VAR although less pronounced and more transient than the ipsilateral one. It is concluded that the local orthostatic stress does evoke more widespread changes affecting distant vascular beds.The present study was supported by the Research Committee of Saba University School of Medicine.

Popular Tales and Fictions: Their Migrations and Transformations (review)

Reviewed by: Popular Tales and Fictions: Their Migrations and Transformations Stephen Benson (bio) Popular Tales and Fictions: Their Migrations and Transformations. By W. A. Clouston . Edited with an introduction by Christine Goldberg . Santa Barbara, CA: ABC-CLIO, 2002. xxxi + 585 pp. Narrative has made something of a comeback in recent years, not least in the academic scramble of the moment. As I write, a British neuropsychologist has won a prestigious general book award for a study of the stories that result from various forms of brain damage (Paul Broks's Into the Silent Land); Dan Lloyd, a philosopher and neuroscientist, has written what he subtitles A Novel Theory of Consciousness (Radiant Cool), in which ideas of the latter (consciousness) are couched in the workings of the former (the novel); and, as might be expected, a literary critic has made the self-evident case that the narratives of the novel are studies of consciousness avant la lettre (David Lodge's Consciousness and the Novel). Analogous work can be found in the field of ethics, where the give and take of storytelling, the proliferating provisionality of narrative, is granted cognitive and ethical value in and of itself. All this is of course interesting news (if it is news) to those of us who deal with the likes of folk and fairy tales. Successive winds of methodological change have generated new, to say nothing of deepening, perspectives on traditions and histories of popular storytelling, and contemporary ethics and the cognitive sciences look set to offer the same possibilities. It is within this perhaps surprising context that the reprint of W. A. Clouston's classic text of storiology is particularly welcome. As read today, it seems of most interest as a study predicated on a protohypertextual conception of narration, whereby the potential explanations of theory are always undermined by the possibility of another link, another click. The relish exhibited by Clouston in the face of his sea of stories is palpable; while the uninhibited expression of such relish is a characteristic sign of a Victorian gentleman scholar at work in the archives, the text itself feels contemporary precisely in its generous openness to narrative. [End Page 303] The two weighty volumes of Popular Tales and Fictions: Their Migrations and Transformations, were originally published in Edinburgh in 1887. The subtitle gives a fair indication of the methodological affiliations of the collection: broadly comparativist, an early version of the historic-geographic approach. There was of course much folkloristic activity in the latter part of the nineteenth century—it was, as Christine Goldberg says, a "new science." Clouston's text is embedded in the thick of the scholarly discourse of the time, in particular the conflicting claims of the comparativists—wedded to the idea of what was then termed an "Asiatic" origin for European folk narrative material—and the survivalists, for whom the tales were distant manifestations of primitive beliefs. Clouston's long introduction is characteristic of the text as a whole, putting its faith in evidence rather than argument. The basic premise is intermittently stated ("most of the popular tales of Europe are traceable to ancient Indian sources"), but by far the bulk of the introduction, as of the text, is taken up with the stories themselves, recounted in varying amounts of detail. As Clouston says, "variants of the same general stories are detailed—not merely indicated by their titles—thus enabling the reader to judge for himself their common origin, and the transformations they have undergone in passing from one country to another." Following the introduction, the first volume comprises chapters devoted to what we would now view broadly as tale motifs ("Dragons and Monstrous Birds"; "Gold-producing Animals"), followed by chapters dealing with tale types ("The Hunchback and the Fairies"; "Aladdin's Wonderful Lamp"). Volume 2 is concerned with what Clouston knew as fictions, those traditional narratives with "little or nothing improbable in their details." The text is testament to Clouston's self-confessed "promiscuous reading," with the narrative material drawn from a dizzying array of European, Near- and Middle-Eastern sources, and from an equally varied set of genres. Needless to say, it continues to offer rich pickings for both general and specialist...

Systemic effects of local allergic disease

Allergic reactions are not confined to the area they originated, but assume a secondary systemic, nonanaphylactic element. This element has two consequences: it feeds back into the site of the original reaction and it leads to the development of distant local manifestations. The well-established interactions between the nasal and the lower airways in allergic disease could be viewed as an example of this model. Interactions between the nasal mucosa and the paranasal sinuses, as well as interactions between the respiratory system, the skin, and the gastrointestinal tract have been described and may also fall under the same category. Two conduits of the systemic element of allergic disease are proposed: the systemic circulation and the nervous system. The mechanisms that lead to the development of the systemic element, and particularly the mechanisms of distant manifestations after a local allergic reaction have not been elucidated, but they probably include intricate interactions between the classic mediators of the acute allergic reaction, locally- and systemically-produced cytokines and neurotrophins, the vascular epithelium and the adhesion molecule system, the chemokine network, antigen-presenting dendritic cells and their interactions with T-lymphocytes, as well as a strong bone marrow component. From this perspective, the systemic element presents an exciting area of current and future research in allergic disease.

Malignant melanoma and 18F-FDG-PET: Should the whole body scan include the legs?

(18)F-FDG-PET (FDG-PET) is established in staging and follow-up of malignant melanoma. The legs are affected in 10-40% at time of diagnosis even if the primary is at the arms and torso. Imaging including the legs may detect distant manifestations but increases duration of the scan by approximately 30 min. We intended to disclose the diagnostic benefit of scanning the legs and to evaluate the therapeutic benefit resulting. In this retrospective analyse 213 consecutive PET studies of 153 patients with suspected or recent malignant melanoma were re-evaluated for metastatic spread by a blinded investigator. Histopathological follow-up was assessed for confirmation. Suspicious findings at the legs were depicted in 53 patients on 76 occasions. 38/53 showed pathologic uptake in the torso as well. In 15/53 patients it was restricted to the legs. One of them had a hitherto unknown, clinically relevant finding that was not apparent in palpation and inspection. In 6 other patients with primary location at the legs a validation of the positive PET findings was not possible up to now. Metastases and local recurrence of malignant melanoma at the legs were found in 41% of women and 27% of men. However, a long scan does not yield relevant additional data. We found isolated new manifestations at the legs in only 1/153 patients. We recommend performing a long scan only in patients with previous melanoma manifestations restricted to the legs. In all other cases a short scan of the torso and proximal thighs is sufficient. This allows a higher number of PET-scans without loss of diagnostic power and a shorter examination time.

Effects of preceding context on the voice-onset-time-category boundary.

The category boundary on a voice-onset-time (VOT) continuum ranging from bin to pin shifts when the stimuli are preceded by different carrier phrases. By using a variety of precursor phrases, by varying the temporal interval between precursor and test word, and by selectively eliminating either voicing information or spectral structure from the precursors, the present experiments show that the context effect is caused by the presence or absence of voicing in the precursor's final segment. The effect decreases with temporal separation but persists over several seconds. In addition, the "baseline" VOT boundary for isolated test words interspersed in a test sequence shifts depending on what precursor stimuli occur in the same sequence. The perception of VOT thus seems to be sensitive to both close and distant manifestations of laryngeal activity, always in an assimilative fashion, which suggests an integrative perceptual mechanism with a long time constant.

Gestational trophoblastic neoplasms: Morphologic considerations

Abnormal trophoblastic proliferation is the hallmark of a spectrum of lesions constituting the gestational trophoblastic neoplasms. Rapid proliferation, infiltration, vascular invasion, hematogenous dissemination, and spontaneous regression are features of both normal and neoplastic trophoblast. Trophoblastic hyperplasia without hydrops, hydatidiform mole, invasive mole, and gestational choriocarcinoma are related lesions, characterized by increasingly aberrant trophoblastic growth and worsening prognosis, if untreated. Difficulties in diagnosis may arise with respect to the normal early implantation site, the hydropic abortus, and postgestational, involuting, residual trophoblast. Histologic grading of hydratidiform moles is relevant to their prognosis and biologic behavior. Trophoblastic neoplasia may begin at any stage of pregnancy or puerperally with immediate or late and local or distant manifestations in the mother or the child. Cognizance of the capricious potential behavior of trophoblast permits successful management of its proliferative lesions, monitored by serial measurement of gonadotropin secretion.

Tectonic Evolution of the Southern Gulf of Mexico

A detailed magnetic survey in the southern Gulf of Mexico shows subdued irregular magnetic anomalies that are similar in wave length to those attributed to sea-floor spreading on present-day oceanic rises. The small amplitude of these anomalies, about 75γ, would be compatible with an oceanic basalt source at a depth of 10 km, and previous seismic refraction studies in this area have shown that layer 2 of the oceanic crust (presumed to be basalt) does indeed lie at approximately that depth. Palynomorphs in Deep Sea Drilling Project samples of cap-rock material from the Sigsbee Knolls have shown the associated salt to be Jurassic. A crustal model, based on seismic refraction evidence and on new gravity data, suggests that, whereas the salt-dome belt of the southern gulf is underlain by a thick layer with a density of 2.2 g per cm 3 (presumed to be halite rock), adjacent deeper areas of the basin seem to lack this low density layer. In northeastern Mexico, Triassic red beds fill grabens that are correlative with the Newark Group of the Atlantic Coast and suggest that the Gulf of Mexico originated at the time of the initial rifting of the North Atlantic. When the gulf was about half-opened during the Jurassic, oceanic circulation was restricted; and thick deep-basin evaporite deposits, analogous to those found in the Mediterranean Sea by the Deep Sea Drilling Project, were laid down. Further opening established normal salinity and led to the development of salt-free areas of oceanic crust that separated the Sigsbee Escarpment (together with adjacent ridges of offshore Mexico) from the Sigsbee Knolls and salt domes of Cuba. The subsequent structural evolution of the Gulf of Mexico basin is believed to have been mainly a result of interaction between it and tectonic plates of the Pacific area. After opening of the gulf, subduction began along the Cuban arc, where Atlantic rifting had created a nearly uninterrupted tract of oceanic crust extending from the Pacific between Yucatan and Colombia. Then, folding and gravity sliding associated with Laramide deformation on the west side of the gulf led to salt anticlines that underlie the ridges offshore from Mexico. Except for continued diapirism and subsidence associated with sediment loading, present tectonic activity is confined to the southwestern corner of the gulf, where volcanism and intermediate-focus earthquakes are a distant manifestation of subduction along the Middle America Trench on the Pacific side of Mexico.