External hernia of the supravesical fossa: Rare or simply misidentified?

BACKGROUND: External hernias of the supravesical fossa are considered rare, perhaps wrongly. Highlighting clinical and anatomical features could be useful for correct, preoperative diagnosis, thus avoiding the risk of complications such as incarceration. The study aims to demonstrate that the incidence of external protrusions of the supravesical fossa is higher that supposed. Probably, being mistaken for direct hernias, these hernia types are misidentified and not included in current classifications. This issue deserves attention due to the elevated risk of incarceration related to its distinctive structure. MATERIAL AND METHODS: 249 consecutive open anterior inguinal hernia procedures were analyzed. Hernias were categorized according to the Nyhus classification. A subgroup of direct hernias involved true hernias of the supravesical fossa. Multiple ipsilateral, as well as combined hernias having a multi-component structure, were also considered. RESULTS: 13 true hernias of the supravesical fossa and 19 multiple ipsilateral or combined hernias composed of direct and/or indirect hernia, together with one hernia of the supravesical fossa were identified. 4 true hernias of the supravesical fossa presented signs of incarceration. In three other combined protrusions, the herniated component of the supravesical fossa also showed incarceration of the visceral content. CONCLUSIONS: Hernias of the supravesical fossa would appear to be more frequent than imagined. These protrusions show a diverticular shape and the base is often tightened by the stiffer medial umbilical fold. This explains the apparently higher tendency to incarceration that distinguishes this hernia type. Preoperative signs of inguinal pain and irreducibility are pathognomonic for correct diagnosis. In these cases, surgical treatment in the short term is recommended.

Zn biomineralization processes and microbial biofilm in a metal-rich stream (Naracauli, Sardinia).

Several decades after the closure of the Ingurtosu mine (SW Sardinia), a variety of seasonal Zn biomineralizations occurs. In this work, waters, microbial consortia, and seasonal precipitates from the Naracauli stream were sampled to investigate chemical composition of stream waters and biominerals, and microbial strain identity. Molecular and morphological analysis revealed that activity of dominant cyanobacterium Leptolyngbya frigida results in precipitation of Zn silicate. The activity of the cyanobacterium was associated to other bacteria and many kind of diatoms, such as Halamphora subsalina and Encyonopsis microcephala, which are trapped in the process of biomineral growth. In this work, the precipitation process is shown to be the result of many different parameters such as hydrologic regime, microbial community adaptation, and biological mediation. It results in a decrease of dissolved Zn in the stream water, and is a potential tool for Zn pollution abatement.

The amorphous Zn biomineralization at Naracauli stream, Sardinia: electron microscopy and X-ray absorption spectroscopy.

An amorphous Zn biomineralization ("white mud"), occurring at Naracauli stream, Sardinia, in association with cyanobacteria Leptolyngbya frigida and diatoms, was investigated by electron microscopy and X-ray absorption spectroscopy. Preliminary diffraction analysis shows that the precipitate sampled on Naracauli stream bed is mainly amorphous, with some peaks ascribable to quartz and phyllosilicates, plus few minor unattributed peaks. Scanning electron microscopy analysis shows that the white mud, precipitated in association with a seasonal biofilm, is made of sheaths rich in Zn, Si, and O, plus filaments likely made of organic matter. Transmission electron microscopy analysis shows that the sheaths are made of smaller units having a size in the range between 100 and 200 nm. X-ray absorption near-edge structure and extended X-ray absorption fine structure data collected at the Zn K-edge indicate that the biomineral has a local structure similar to hemimorphite, a zinc sorosilicate. The differences of this biomineral with respect to the hydrozincite biomineralization documented about 3 km upstream in the same Naracauli stream may be related to either variations in the physicochemical parameters and/or different metabolic behavior of the involved biota.

Heavy metal coprecipitation with hydrozincite [Zn(5)(CO(3))(2)(OH)(6)] from mine waters caused by photosynthetic microorganisms.

An iron-poor stream of nearly neutral pH polluted by mine tailings has been investigated for a natural phenomenon responsible for the polishing of heavy metals in mine wastewaters. A white mineralized mat, which was determined to be hydrozincite [Zn(5)(CO(3))(2)(OH)(6)] by X-ray diffraction analysis, was observed in the stream sediments mainly in spring. The precipitate shows a total organic matter residue of 10% dry weight and contains high concentrations of Pb, Cd, Ni, Cu, and other metals. Scanning electron microscopy analysis suggests that hydrozincite is mainly of biological origin. Dormant photosynthetic microorganisms have been retrieved from 1-year-old dry hydrozincite. The autofluorescent microorganisms were imaged by a scanning confocal laser microscope. A photosynthetic filamentous bacterium, classified as Scytonema sp. strain ING-1, was found associated with microalga Chlorella sp. strain SA1. This microbial community is responsible for the natural polishing of heavy metals in the water stream by coprecipitation with hydrozincite.